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obscura/crates/obscura-render/src/paint.rs
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//! Paint: rasterize the laid-out DOM into a [`tiny_skia::Pixmap`].
//!
//! Phase 5a. Fills each element's border box with its background color over a
//! white page. Text rendering arrives with the text step; borders and images
//! are later enhancements. Pure Rust (tiny-skia, CPU), deterministic, no system
//! dependencies, so a screenshot is reproducible across hosts.
use obscura_dom::tree::DomTree;
use tiny_skia::{Color, FillRule, GradientStop, LinearGradient, Paint, PathBuilder, Pixmap, Point, RadialGradient, Rect, SpreadMode, Transform};
use ab_glyph::{Font, FontRef, PxScale, ScaleFont};
use std::collections::{HashMap, VecDeque};
use std::sync::Arc;
static FONT_BYTES: &[u8] = include_bytes!("../assets/liberation-sans.ttf");
static SERIF_FONT_BYTES: &[u8] = include_bytes!("../assets/liberation-serif.ttf");
static MONO_FONT_BYTES: &[u8] = include_bytes!("../assets/liberation-mono.ttf");
static FONT_BOLD_BYTES: &[u8] = include_bytes!("../assets/liberation-sans-bold.ttf");
static FONT_OBLIQUE_BYTES: &[u8] = include_bytes!("../assets/liberation-sans-oblique.ttf");
static FONT_BOLD_OBLIQUE_BYTES: &[u8] = include_bytes!("../assets/liberation-sans-boldoblique.ttf");
use crate::dom::layout_dom_with_web_fonts;
const DEFAULT_RESOURCE_CACHE_ENTRIES: usize = 512;
const DEFAULT_RESOURCE_CACHE_BYTES: usize = 64 * 1024 * 1024;
const MISSING_RESOURCE_RETRY_AFTER: std::time::Duration = std::time::Duration::from_secs(2);
/// Synchronous byte loader used by [`RenderResourceCache`]. The default
/// implementation uses Obscura's pooled image agent; tests and embedding
/// callers can provide a local loader without changing preparation or paint.
pub trait RenderResourceLoader {
fn load(&mut self, url: &str) -> Option<Vec<u8>>;
}
impl<F> RenderResourceLoader for F
where
F: FnMut(&str) -> Option<Vec<u8>>,
{
fn load(&mut self, url: &str) -> Option<Vec<u8>> {
self(url)
}
}
struct HttpResourceLoader;
impl RenderResourceLoader for HttpResourceLoader {
fn load(&mut self, url: &str) -> Option<Vec<u8>> {
http_get_bytes(url)
}
}
enum CachedResource {
Bytes(Arc<[u8]>),
Missing(std::time::Instant),
}
/// Page-scoped raw resource bytes shared by layout preparation and repeated
/// paints. Entries are FIFO-bounded by both count and retained byte size.
/// Successful bytes use `Arc` so consumers never clone an image/font body.
pub struct RenderResourceCache {
entries: HashMap<String, CachedResource>,
order: VecDeque<String>,
retained_bytes: usize,
max_entries: usize,
max_bytes: usize,
loader: Box<dyn RenderResourceLoader>,
}
impl Default for RenderResourceCache {
fn default() -> Self {
Self::with_loader_and_limits(
HttpResourceLoader,
DEFAULT_RESOURCE_CACHE_ENTRIES,
DEFAULT_RESOURCE_CACHE_BYTES,
)
}
}
impl RenderResourceCache {
pub fn with_loader(loader: impl RenderResourceLoader + 'static) -> Self {
Self::with_loader_and_limits(
loader,
DEFAULT_RESOURCE_CACHE_ENTRIES,
DEFAULT_RESOURCE_CACHE_BYTES,
)
}
pub fn with_loader_and_limits(
loader: impl RenderResourceLoader + 'static,
max_entries: usize,
max_bytes: usize,
) -> Self {
Self {
entries: HashMap::new(),
order: VecDeque::new(),
retained_bytes: 0,
max_entries,
max_bytes,
loader: Box::new(loader),
}
}
pub fn retained_entry_count(&self) -> usize {
self.entries.len()
}
pub fn retained_byte_len(&self) -> usize {
self.retained_bytes
}
/// Resolve, fetch, and inspect one image through the exact byte cache used
/// by layout and paint. The JS image-element lifecycle calls this narrow
/// bridge so `complete`/`naturalWidth` and the eventual screenshot are
/// driven by one resource outcome instead of issuing an independent fetch.
///
/// This intentionally accepts a plain `src`, not a DOM node: responsive
/// `picture`/`srcset` selection remains owned by `prepare_dom`.
pub fn image_metadata(
&mut self,
src: &str,
base_url: Option<&str>,
) -> Option<(String, f32, f32)> {
let resolved_url = resolve_resource_url(src, base_url)?;
let bytes = fetch_bytes(&resolved_url, None, self)?;
let (width, height) = image_metadata_from_bytes(&bytes)?;
Some((resolved_url, width, height))
}
/// Inspect an image only when its renderer-cache outcome is already known.
/// `None` means no live cache entry (the caller may queue a load);
/// `Some(None)` means a retained load/decode failure; `Some(Some(...))`
/// means success. `data:` sources have no network entry and are cheap to
/// inspect directly.
pub fn cached_image_metadata(
&self,
src: &str,
base_url: Option<&str>,
) -> Option<Option<(String, f32, f32)>> {
let resolved_url = resolve_resource_url(src, base_url)?;
if resolved_url.starts_with("data:") {
let mut scratch = RenderResourceCache::with_loader_and_limits(
|_url: &str| None,
0,
0,
);
return Some(
fetch_bytes(&resolved_url, None, &mut scratch)
.and_then(|bytes| image_metadata_from_bytes(&bytes))
.map(|(width, height)| (resolved_url, width, height)),
);
}
match self.entries.get(&resolved_url) {
Some(CachedResource::Bytes(bytes)) => Some(
image_metadata_from_bytes(bytes)
.map(|(width, height)| (resolved_url, width, height)),
),
Some(CachedResource::Missing(at))
if at.elapsed() < MISSING_RESOURCE_RETRY_AFTER =>
{
Some(None)
}
_ => None,
}
}
/// Select and inspect the resource for one live `<img>` using the same
/// `picture`/`srcset`/`sizes` algorithm as `collect_image_intrinsics`.
/// Dimensions are returned in CSS pixels after candidate-density scaling.
/// A selected URL with `None` dimensions is an authoritative load/decode
/// failure.
pub fn image_element_metadata(
&mut self,
tree: &DomTree,
id: obscura_dom::tree::NodeId,
viewport: (f32, f32),
base_url: Option<&str>,
) -> Option<(String, f32, Option<(f32, f32)>)> {
let (src, density) = resolve_img_url(tree, id, viewport)?;
let resolved_url = resolve_resource_url(&src, base_url).unwrap_or(src);
let dimensions = fetch_bytes(&resolved_url, None, self)
.and_then(|bytes| image_metadata_from_bytes(&bytes))
.map(|(width, height)| (width / density, height / density));
Some((resolved_url, density, dimensions))
}
/// Cache-only counterpart to [`Self::image_element_metadata`]. The boolean
/// is false only when the selected candidate has no live cache outcome;
/// callers may queue the loading form without ever blocking a getter.
pub fn cached_image_element_metadata(
&self,
tree: &DomTree,
id: obscura_dom::tree::NodeId,
viewport: (f32, f32),
base_url: Option<&str>,
) -> Option<(String, f32, bool, Option<(f32, f32)>)> {
let (src, density) = resolve_img_url(tree, id, viewport)?;
let resolved_url = resolve_resource_url(&src, base_url).unwrap_or(src);
match self.cached_image_metadata(&resolved_url, None) {
None => Some((resolved_url, density, false, None)),
Some(dimensions) => Some((
resolved_url,
density,
true,
dimensions.map(|(_, width, height)| (width / density, height / density)),
)),
}
}
fn get_or_load(&mut self, url: &str) -> Option<Arc<[u8]>> {
if let Some(entry) = self.entries.get(url) {
match entry {
CachedResource::Bytes(bytes) => return Some(Arc::clone(bytes)),
CachedResource::Missing(at)
if at.elapsed() < MISSING_RESOURCE_RETRY_AFTER =>
{
return None;
}
CachedResource::Missing(_) => {}
}
}
self.remove(url);
let loaded = self.loader.load(url).map(Arc::<[u8]>::from);
match loaded {
Some(bytes) => {
self.insert_bytes(url.to_string(), Arc::clone(&bytes));
Some(bytes)
}
None => {
self.insert_missing(url.to_string());
None
}
}
}
fn insert_bytes(&mut self, url: String, bytes: Arc<[u8]>) {
if self.max_entries == 0 || bytes.len() > self.max_bytes {
return;
}
while self.entries.len() >= self.max_entries
|| self.retained_bytes.saturating_add(bytes.len()) > self.max_bytes
{
let Some(oldest) = self.order.pop_front() else {
break;
};
self.remove_entry(&oldest);
}
self.retained_bytes = self.retained_bytes.saturating_add(bytes.len());
self.order.push_back(url.clone());
self.entries.insert(url, CachedResource::Bytes(bytes));
}
fn insert_missing(&mut self, url: String) {
if self.max_entries == 0 {
return;
}
while self.entries.len() >= self.max_entries {
let Some(oldest) = self.order.pop_front() else {
break;
};
self.remove_entry(&oldest);
}
self.order.push_back(url.clone());
self.entries
.insert(url, CachedResource::Missing(std::time::Instant::now()));
}
fn remove(&mut self, url: &str) {
if self.entries.contains_key(url) {
self.order.retain(|key| key != url);
self.remove_entry(url);
}
}
fn remove_entry(&mut self, url: &str) {
if let Some(CachedResource::Bytes(bytes)) = self.entries.remove(url) {
self.retained_bytes = self.retained_bytes.saturating_sub(bytes.len());
}
}
}
/// The exact responsive image candidate chosen during preparation.
#[derive(Clone, Debug, PartialEq)]
pub struct SelectedImage {
pub resolved_url: String,
pub density: f32,
}
/// A final image/font-aware document layout retained across viewport paints.
/// The DOM must not be mutated while this value is reused.
pub struct PreparedRender {
viewport: (f32, f32),
base_url: Option<String>,
content_size: (f32, f32),
viewport_fixed: std::collections::HashSet<obscura_dom::tree::NodeId>,
sticky: crate::StickyLayout,
selected_images: HashMap<obscura_dom::tree::NodeId, SelectedImage>,
svg_fonts: Arc<usvg::fontdb::Database>,
layout: crate::DomLayout,
}
impl PreparedRender {
pub fn viewport(&self) -> (f32, f32) {
self.viewport
}
pub fn base_url(&self) -> Option<&str> {
self.base_url.as_deref()
}
pub fn layout(&self) -> &crate::DomLayout {
&self.layout
}
pub fn content_size(&self) -> (f32, f32) {
self.content_size
}
pub fn viewport_fixed_nodes(
&self,
) -> &std::collections::HashSet<obscura_dom::tree::NodeId> {
&self.viewport_fixed
}
pub fn sticky_layout(&self) -> &crate::StickyLayout {
&self.sticky
}
pub fn clamp_scroll(&self, requested: (f32, f32)) -> (f32, f32) {
let clamp_axis = |requested: f32, content: f32, viewport: f32| {
if requested.is_finite() {
requested.clamp(0.0, (content - viewport).max(0.0))
} else {
0.0
}
};
(
clamp_axis(requested.0, self.content_size.0, self.viewport.0),
clamp_axis(requested.1, self.content_size.1, self.viewport.1),
)
}
/// Border box in immutable document space, including authored translate
/// transforms but excluding root-scroll and sticky movement.
pub fn document_rect(
&self,
id: obscura_dom::tree::NodeId,
) -> Option<crate::Rect> {
let rect = *self.layout.rects.get(&id)?;
let offset = self
.layout
.translates
.get(&id)
.copied()
.unwrap_or((0.0, 0.0));
Some(crate::Rect {
x: rect.x + offset.0,
y: rect.y + offset.1,
..rect
})
}
/// Border box in the current root viewport. This is the read-only geometry
/// path used by a later CSSOM integration and shares paint's clamped scroll,
/// fixed-subtree, and sticky-positioning derivatives.
pub fn viewport_rect(
&self,
id: obscura_dom::tree::NodeId,
requested_scroll: (f32, f32),
) -> Option<crate::Rect> {
let mut rect = self.document_rect(id)?;
let scroll = self.clamp_scroll(requested_scroll);
if !self.viewport_fixed.contains(&id) {
let sticky = self.sticky.translation_for(id, self.viewport, scroll);
rect.x += sticky.0 - scroll.0;
rect.y += sticky.1 - scroll.1;
}
Some(rect)
}
pub fn selected_image(
&self,
id: obscura_dom::tree::NodeId,
) -> Option<&SelectedImage> {
self.selected_images.get(&id)
}
}
/// Render `tree` at `viewport` (width, height) in CSS pixels to a Pixmap, or
/// None if the viewport is zero-sized. `base_url`, when given, resolves the
/// relative image URLs (`<img src="logo.svg">`) that make up the overwhelming
/// majority of real-world markup; without it only absolute and `data:` URLs
/// can be fetched.
pub fn paint_dom(tree: &DomTree, viewport: (f32, f32), base_url: Option<&str>) -> Option<Pixmap> {
paint_dom_scrolled(tree, viewport, base_url, (0.0, 0.0))
}
/// Render the visible viewport after root scrolling. Normal document content
/// is translated by the clamped scroll offset while viewport-fixed subtrees
/// remain anchored to the initial containing block.
pub fn paint_dom_scrolled(
tree: &DomTree,
viewport: (f32, f32),
base_url: Option<&str>,
scroll: (f32, f32),
) -> Option<Pixmap> {
let mut resources = RenderResourceCache::default();
let mut prepared = prepare_dom(tree, viewport, base_url, &mut resources)?;
paint_prepared(tree, &mut prepared, &mut resources, scroll)
}
/// Resolve image candidates and web fonts, then create the single final layout
/// shared by CSS geometry consumers and repeated paint.
pub fn prepare_dom(
tree: &DomTree,
viewport: (f32, f32),
base_url: Option<&str>,
resources: &mut RenderResourceCache,
) -> Option<PreparedRender> {
if !viewport.0.is_finite()
|| !viewport.1.is_finite()
|| viewport.0 <= 0.0
|| viewport.1 <= 0.0
{
return None;
}
// Fetch <img> bytes up front to learn intrinsic sizes for layout (a
// CSS-sized image with no width/height attribute would otherwise be 0x0
// and never paint). This seeds the same cache the paint pass reads, so
// each URL is still fetched at most once.
let (mut intrinsic, mut selected_images) =
collect_image_intrinsics(tree, viewport, base_url, resources);
let fonts = collect_web_fonts(tree, base_url, resources);
// Most framework pages use web fonts and many decorative SVG icons, but
// only SVG text needs the page font faces. Avoid cloning/loading the page
// font database for ordinary icons and HTML-only text.
let svg_fonts = if has_inline_svg_text(tree) {
svg_font_database_with_web_fonts(&fonts)
} else {
svg_font_database()
};
let mut laid = layout_dom_with_web_fonts(tree, viewport, &intrinsic, &fonts);
// `content:url(...)` is computed by the author cascade, whereas ordinary
// HTML image sources are available before layout. Pay for a second layout
// only on the uncommon pages that actually use a CSS image as replaced
// content: its metadata then enters the same intrinsic-size map as `src`.
if collect_content_image_intrinsics(
tree,
&laid.styles,
base_url,
resources,
&mut intrinsic,
&mut selected_images,
) {
laid = layout_dom_with_web_fonts(tree, viewport, &intrinsic, &fonts);
}
let content_size = laid.scrolling_content_size(tree, viewport);
let viewport_fixed = laid.viewport_fixed_nodes(tree);
let sticky = laid.root_sticky_layout(tree, viewport);
Some(PreparedRender {
viewport,
base_url: base_url.map(str::to_string),
content_size,
viewport_fixed,
sticky,
selected_images,
svg_fonts,
layout: laid,
})
}
/// Paint one root-scroll position from an already prepared resource-aware
/// layout. Resource bytes and glyph caches are reused across calls.
pub fn paint_prepared(
tree: &DomTree,
prepared: &mut PreparedRender,
resources: &mut RenderResourceCache,
scroll: (f32, f32),
) -> Option<Pixmap> {
let (w, h) = (prepared.viewport.0 as u32, prepared.viewport.1 as u32);
let mut pixmap = Pixmap::new(w, h)?;
pixmap.fill(Color::WHITE);
paint_laid_dom_scrolled(
tree,
prepared.viewport,
prepared.base_url.as_deref(),
scroll,
pixmap,
resources,
&prepared.selected_images,
&prepared.svg_fonts,
prepared.content_size,
&prepared.viewport_fixed,
&prepared.sticky,
&mut prepared.layout,
)
}
/// Paint an already prepared layout without changing its document-space
/// geometry. Root scrolling and sticky positioning are per-shot visual state,
/// so alternating captures can safely reuse the same layout.
fn paint_laid_dom_scrolled(
tree: &DomTree,
viewport: (f32, f32),
base_url: Option<&str>,
scroll: (f32, f32),
mut pixmap: Pixmap,
image_cache: &mut RenderResourceCache,
selected_images: &HashMap<obscura_dom::tree::NodeId, SelectedImage>,
svg_fonts: &Arc<usvg::fontdb::Database>,
content_size: (f32, f32),
viewport_fixed: &std::collections::HashSet<obscura_dom::tree::NodeId>,
sticky: &crate::StickyLayout,
laid: &mut crate::DomLayout,
) -> Option<Pixmap> {
let scroll_state =
ScrollPaintState::new(viewport, scroll, content_size, viewport_fixed, sticky);
// Only raster images inside an actually rotated/scaled subtree receive an
// affine entry. Ordinary pages pay one fast style scan and allocate no
// matrix map; transformed pages do matrix work only along those subtrees.
let projected_images = collect_projected_image_transforms(tree, laid, &scroll_state);
let root_font_size = tree
.query_selector("html")
.ok()
.flatten()
.and_then(|root| laid.styles.get(&root))
.and_then(|style| style.font_size)
.unwrap_or(16.0);
// Nodes that live inside an inline `<svg>` we rasterized as one document;
// their painting is owned by that raster, so they are skipped in both the
// box/text loop below and the inline-formatting loop after it (an svg
// `<text>` element must not also paint its glyphs on top of the raster).
let mut svg_subtree_skip: std::collections::HashSet<obscura_dom::tree::NodeId> = std::collections::HashSet::new();
// External sprite symbols, keyed by "url#id", extracted from a fetched
// sprite file so a `<use href="url#id">` resolves. One sprite backs many
// icons (a whole logo/icon band), so cache the parsed symbol across every
// inline svg on the page rather than re-parsing the sprite per icon.
let mut sprite_cache: std::collections::HashMap<String, Option<String>> = std::collections::HashMap::new();
// Whether any element carries a `transform: translate()`. When none does
// (the overwhelmingly common case), every node's accumulated offset is
// zero, so skip the per-node ancestor walk entirely and keep the paint
// path free of any added cost.
// Paint order: tree order for the normal flow (later elements paint over
// earlier ones), except that a positioned element with a non-zero
// z-index lifts its whole subtree into a separate layer: negative layers
// paint under the normal flow, positive ones above it, each sorted by
// z-index ascending (stable, so equal z keeps tree order). This is the
// pragmatic core of CSS stacking contexts: dropdowns/overlays/badges
// (z>0) stop losing to later siblings, and z:-1 decorative backdrops
// stop covering their content. Nested z roots paint inside their
// ancestor root's subtree in tree order.
let mut neg_layers: Vec<(i32, Vec<obscura_dom::tree::NodeId>)> = Vec::new();
let mut pos_layers: Vec<(i32, Vec<obscura_dom::tree::NodeId>)> = Vec::new();
let mut normal: Vec<obscura_dom::tree::NodeId> = Vec::new();
let mut consumed: std::collections::HashSet<obscura_dom::tree::NodeId> = std::collections::HashSet::new();
for nid in tree.descendants(tree.document()) {
if consumed.contains(&nid) {
continue;
}
let z = laid
.styles
.get(&nid)
.filter(|s| s.position.is_some())
.and_then(|s| s.z_index)
.filter(|&z| z != 0);
if let Some(z) = z {
let mut sub = vec![nid];
sub.extend(tree.descendants(nid));
for &m in &sub {
consumed.insert(m);
}
if z < 0 {
neg_layers.push((z, sub));
} else {
pos_layers.push((z, sub));
}
} else {
normal.push(nid);
}
}
neg_layers.sort_by_key(|(z, _)| *z);
pos_layers.sort_by_key(|(z, _)| *z);
let paint_order: Vec<obscura_dom::tree::NodeId> = neg_layers
.into_iter()
.flat_map(|(_, sub)| sub)
.chain(normal)
.chain(pos_layers.into_iter().flat_map(|(_, sub)| sub))
.collect();
// Generated boxes are anonymous layout children. ::before paints directly
// after its host's own box; ::after paints after the host's last DOM
// descendant in this paint order. Build the latter schedule only on pages
// that actually materialized a generated box. A reverse DOM-preorder pass
// propagates each node's paint index to its parent once, deriving subtree
// endpoints in O(nodes + generated boxes), including reordered z layers.
let mut generated_before: std::collections::HashMap<
obscura_dom::tree::NodeId,
Vec<crate::dom::GeneratedBox>,
> = std::collections::HashMap::new();
let mut generated_after_at: Vec<Vec<crate::dom::GeneratedBox>> =
vec![Vec::new(); paint_order.len()];
if !laid.generated_boxes.is_empty() {
let paint_indices: std::collections::HashMap<obscura_dom::tree::NodeId, usize> =
paint_order
.iter()
.enumerate()
.map(|(index, &nid)| (nid, index))
.collect();
let mut last_index: std::collections::HashMap<obscura_dom::tree::NodeId, usize> =
paint_indices.clone();
let dom_preorder = tree.descendants(tree.document());
for nid in dom_preorder.into_iter().rev() {
let Some(index) = last_index.get(&nid).copied() else {
continue;
};
if let Some(parent) = tree.get_node(nid).and_then(|node| node.parent) {
last_index
.entry(parent)
.and_modify(|last| *last = (*last).max(index))
.or_insert(index);
}
}
for generated in laid.generated_boxes.iter().copied() {
match generated.kind {
crate::dom::GeneratedBoxKind::Before => {
generated_before
.entry(generated.host)
.or_default()
.push(generated);
}
crate::dom::GeneratedBoxKind::After => {
if let Some(index) = last_index.get(&generated.host) {
generated_after_at[*index].push(generated);
}
}
}
}
}
for (paint_index, nid) in paint_order.into_iter().enumerate() {
if svg_subtree_skip.contains(&nid) {
continue;
}
let node = match tree.get_node(nid) {
Some(n) => n,
None => continue,
};
if node.is_text() {
paint_text_node(tree, nid, laid, &scroll_state, &mut pixmap);
for generated in &generated_after_at[paint_index] {
paint_in_flow_generated_box(
&mut pixmap,
generated,
laid,
&scroll_state,
viewport,
root_font_size,
base_url,
image_cache,
);
}
continue;
}
let name = match node.as_element() {
Some(name) => name,
None => continue,
};
let rect = match laid.rects.get(&nid) {
Some(r) => *r,
None => continue,
};
let style = match laid.styles.get(&nid) {
Some(s) => s,
None => continue,
};
if style.effectively_invisible {
continue;
}
// A `transform: translate()` on this element or any ancestor offsets
// this element's whole painted box (and, applied per node, its whole
// subtree). The box shifts into screen space. The inherited clip is
// owner-shifted by layout and root-scroll/sticky-adjusted by the visual
// state, but it must not move with this descendant: that is what lets a
// clip cull a slide the carousel track translated out of its viewport.
let (ox, oy) = scroll_state.translation_for(laid, nid);
let rect = crate::Rect { x: rect.x + ox, y: rect.y + oy, width: rect.width, height: rect.height };
// Ancestor `overflow: hidden` clip, if any. Skip painting entirely
// once the box has no visible overlap with it (this is what makes the
// ubiquitous 1x1 clipped "visually hidden" accessibility pattern
// actually invisible instead of painting text wherever it lands).
let clip = scroll_state.clip_for(laid, nid);
let projected_image = projected_images.get(&nid).copied();
let cull_rect = projected_image
.map(|transform| transform.map_rect(rect))
.unwrap_or(rect);
let visible_rect = match clip {
Some(c) => match cull_rect.intersect(&c) {
Some(r) => r,
None => continue,
},
None => cull_rect,
};
let box_rect = match Rect::from_xywh(visible_rect.x, visible_rect.y, visible_rect.width, visible_rect.height) {
Some(r) => r,
None => continue,
};
// Outset box-shadow paints behind this element's own background/border.
// Geometry comes from the full (translate-adjusted) border box; the
// ancestor overflow clip is reapplied inside so the shadow is clipped by
// an ancestor exactly as the box itself is.
if let Some(shadow) = style.box_shadow {
paint_box_shadow(&mut pixmap, &shadow, &rect, style.border_radius, clip);
}
// Box path (rounded if border-radius), reused for gradient/color fill.
let r = style.border_radius;
let bg_path = || if r > 0.5 {
rounded_rect_path(visible_rect.x, visible_rect.y, visible_rect.width, visible_rect.height, r)
} else {
let mut pb = PathBuilder::new();
pb.push_rect(box_rect);
pb.finish()
};
// A linear-gradient background (heavily used by modern hero sections);
// without this it paints white. Takes precedence over a solid color.
// `background-clip: text` clips the background to the glyphs, so it must
// not paint as a box here; the text paint path fills the glyphs instead.
if style.mask_image.is_none() && !style.background_clip_text {
if let Some(bg) = style.background_color {
if let Some(path) = bg_path() {
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(bg[0], bg[1], bg[2], bg[3]));
paint.anti_alias = r > 0.5;
pixmap.fill_path(
&path,
&paint,
FillRule::Winding,
Transform::identity(),
None,
);
}
}
if let Some((center, stops)) = &style.background_radial_gradient {
if let Some(path) = bg_path() {
paint_radial_gradient(
&mut pixmap,
&path,
&visible_rect,
*center,
stops,
);
}
}
if let Some((angle, center, stops)) = &style.background_conic_gradient {
paint_conic_gradient(&mut pixmap, &visible_rect, *angle, *center, stops);
}
if let Some((angle, stops)) = &style.background_gradient {
if let Some(path) = bg_path() {
paint_linear_gradient(&mut pixmap, &path, &visible_rect, *angle, stops);
}
}
}
if let Some(mask_url) = &style.mask_image {
let fill = style.background_color.or(style.color).unwrap_or([0, 0, 0, 255]);
paint_mask(
mask_url,
base_url,
&visible_rect,
fill,
style.background_gradient.as_ref(),
style.background_conic_gradient.as_ref(),
style.mask_size,
style.mask_repeat,
&mut pixmap,
image_cache,
);
} else if let Some(bg_url) = &style.background_image {
if let Some(img_rect) = background_image_rect(
bg_url,
base_url,
&rect,
style.background_size,
style.background_size_expression.as_deref(),
style.background_size_fit,
style.background_position,
style.font_size.unwrap_or(16.0),
root_font_size,
viewport,
image_cache,
) {
// A background layer is always clipped to its owner's border
// box and then to inherited overflow. Keep its full destination
// rect separate from that clip: intersecting first and then
// scaling would resize a partially clipped image.
let visible = match clip {
Some(c) => rect.intersect(&c),
None => Some(rect),
};
if let Some(visible) = visible {
paint_image(
bg_url,
base_url,
&img_rect,
&visible,
crate::ObjectFit::Fill,
&mut pixmap,
image_cache,
None,
);
}
}
}
for pseudo in [style.before_pseudo.as_deref(), style.after_pseudo.as_deref()]
.into_iter()
.flatten()
{
paint_positioned_pseudo(
&mut laid.text_engine,
&mut pixmap,
pseudo,
&rect,
viewport,
root_font_size,
clip,
base_url,
image_cache,
);
}
// Rounded, uniform border: stroke the rounded-rect outline instead of
// four sharp edge rects.
let uniform_border = style.border.top == style.border.right
&& style.border.right == style.border.bottom
&& style.border.bottom == style.border.left
&& style.border.top > 0.0;
if style.border_radius > 0.5 && uniform_border {
let bc = style.border_color.or(style.color).unwrap_or([0, 0, 0, 255]);
let w = style.border.top;
if let Some(path) = rounded_rect_path(rect.x + w / 2.0, rect.y + w / 2.0, rect.width - w, rect.height - w, (style.border_radius - w / 2.0).max(0.0)) {
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(bc[0], bc[1], bc[2], bc[3]));
paint.anti_alias = true;
let stroke = tiny_skia::Stroke { width: w, ..Default::default() };
pixmap.stroke_path(&path, &paint, &stroke, Transform::identity(), None);
}
} else if style.border.top > 0.0 || style.border.right > 0.0 || style.border.bottom > 0.0 || style.border.left > 0.0 {
let bc = style.border_color.or(style.color).unwrap_or([0, 0, 0, 255]);
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(bc[0], bc[1], bc[2], bc[3]));
paint.anti_alias = false;
let mut path = PathBuilder::new();
let mut push_clipped = |x: f32, y: f32, w: f32, h: f32| {
let edge = crate::Rect { x, y, width: w, height: h };
let edge = match clip { Some(c) => edge.intersect(&c), None => Some(edge) };
if let Some(e) = edge {
if let Some(r) = Rect::from_xywh(e.x, e.y, e.width, e.height) {
path.push_rect(r);
}
}
};
if style.border.top > 0.0 {
push_clipped(rect.x, rect.y, rect.width, style.border.top);
}
if style.border.right > 0.0 {
push_clipped(rect.x + rect.width - style.border.right, rect.y, style.border.right, rect.height);
}
if style.border.bottom > 0.0 {
push_clipped(rect.x, rect.y + rect.height - style.border.bottom, rect.width, style.border.bottom);
}
if style.border.left > 0.0 {
push_clipped(rect.x, rect.y, style.border.left, rect.height);
}
if let Some(path) = path.finish() {
pixmap.fill_path(&path, &paint, FillRule::Winding, Transform::identity(), None);
}
}
if name.local.as_ref() == "img" {
if let Some(source) = selected_images.get(&nid) {
// `visible_rect` is the border box already intersected with the
// ancestor overflow clip: the raster must not paint past it (a
// half-scrolled carousel slide's image otherwise bleeds over
// the viewport edge).
let painted =
paint_image(
&source.resolved_url,
None,
&rect,
&visible_rect,
style.object_fit,
&mut pixmap,
image_cache,
projected_image,
);
// Fall back when the image itself did not paint, following
// what browsers show for a broken image: a non-empty alt
// renders as text in place of the image (no placeholder box),
// alt="" renders nothing at all (the author declared the
// image decorative), and only a MISSING alt keeps the neutral
// grey placeholder. box_rect/visible_rect are already
// clip-intersected, so none of this paints outside an
// overflow:hidden clip.
if !painted {
match node.get_attribute("alt") {
Some(alt) if !alt.trim().is_empty() => {
draw_text(
&mut pixmap,
&alt,
rect.x,
rect.y,
[0, 0, 0, 255],
12.0,
false,
None,
0.0,
clip,
);
}
Some(_) => {}
None => {
if visible_rect.width >= 4.0 && visible_rect.height >= 4.0 {
let mut ph = Paint::default();
ph.set_color(Color::from_rgba8(0xE9, 0xEA, 0xEC, 0xFF));
pixmap.fill_rect(box_rect, &ph, Transform::identity(), None);
}
}
}
}
}
}
// Inline `<svg>...</svg>`: serialize the whole subtree back to one
// standalone SVG document and rasterize it as a unit, so a
// `<use href="#id">` resolves against the `<symbol>`/`<defs>` in the
// same svg. The raster owns the subtree, so its DOM children are not
// painted individually (they are added to `svg_subtree_skip`). The svg
// is drawn at its full border-box size (undistorted) and clipped to the
// overflow-visible region.
if name.local.as_ref() == "svg" {
let mut markup = serialize_svg_styled(tree, nid, &laid.styles);
// Resolve referenced symbols before carrying the host color into
// the standalone document. A document-level/external symbol may
// itself contain `currentColor`, and therefore has to be present
// when the root color is established.
inject_external_sprites(tree, nid, base_url, &mut markup, image_cache, &mut sprite_cache);
// resvg parses the serialized subtree as a standalone SVG
// document, outside the page's author stylesheet. Preserve the
// host element's computed `color` so paths using `currentColor`
// (the standard framework-logo/icon pattern) do not fall back to
// black.
if let Some(color) = style.color {
inject_svg_current_color(&mut markup, color);
}
// `<use href="url#id">` pointing at an EXTERNAL sprite file resolves
// to nothing in resvg (the symbol lives in another document). Fetch
// the sprite, splice the referenced `<symbol>` into a local `<defs>`,
// and rewrite the href to a same-document `#id`. Same-document
// `<use href="#id">` (empty url) is untouched.
if let Some(content) = render_svg_with_font_database(
markup.as_bytes(),
rect.width as u32,
rect.height as u32,
&svg_fonts,
) {
let mask = clip
.and_then(|_| rect_clip_mask(pixmap.width(), pixmap.height(), &visible_rect));
pixmap.draw_pixmap(
rect.x as i32,
rect.y as i32,
content.as_ref(),
&tiny_skia::PixmapPaint::default(),
Transform::identity(),
mask.as_ref(),
);
}
for child in tree.descendants(nid) {
svg_subtree_skip.insert(child);
}
}
if let Some(generated) = generated_before.get(&nid) {
for generated in generated {
paint_in_flow_generated_box(
&mut pixmap,
generated,
laid,
&scroll_state,
viewport,
root_font_size,
base_url,
image_cache,
);
}
}
// List-item marker (bullet or number), drawn in the indent to the left
// of the item's content box. `list_style` is inherited and resolved,
// so `None` (e.g. a nav `<ul style="list-style:none">`) suppresses it.
if name.local.as_ref() == "li" {
if let Some(marker) = list_marker_text(tree, nid, style.list_style) {
let fsize = style.font_size.unwrap_or(16.0);
let color = style.color.unwrap_or([0, 0, 0, 255]);
let mw = measure_text(&marker, fsize, false, style.font_family.as_deref());
let mx = rect.x + style.padding.left - mw - 6.0;
let my = rect.y + style.border.top + style.padding.top;
draw_text(
&mut pixmap,
&marker,
mx,
my,
color,
fsize,
false,
style.font_family.as_deref(),
style.letter_spacing.unwrap_or(0.0),
clip,
);
}
}
// `::before`/`::after` generated text (see `dom::build_pseudo_content`)
// has no DOM text node of its own; its word runs are registered under
// the host element's own id instead, so paint them here rather than
// through `paint_text_node` (which only runs for real text nodes).
if let Some(runs) = laid.text_runs.get(&nid) {
let color = style.color.unwrap_or([0, 0, 0, 255]);
let fsize = style.font_size.unwrap_or(16.0);
let is_bold = crate::style::used_font_weight(style) >= 600;
for (word_rect, word) in runs {
draw_text(
&mut pixmap,
word,
word_rect.x + ox,
word_rect.y + oy,
color,
fsize,
is_bold,
style.font_family.as_deref(),
style.letter_spacing.unwrap_or(0.0),
clip,
);
}
}
// A closed native `<select>` paints only its selected option. Options
// themselves are popup content (`display:none` in the layout tree),
// so the label and disclosure arrow belong to the atomic control.
if name.local.as_ref() == "select" {
if let Some(label) = selected_option_label(tree, nid) {
let fsize = style.font_size.unwrap_or(13.333_333);
let line_height = crate::inline::used_line_height(style);
let text_x = rect.x + style.border.left + style.padding.left;
let text_y = rect.y + (rect.height - line_height) / 2.0;
draw_text(
&mut pixmap,
&label,
text_x,
text_y,
style.color.unwrap_or([0, 0, 0, 255]),
fsize,
crate::style::used_font_weight(style) >= 600,
style.font_family.as_deref(),
style.letter_spacing.unwrap_or(0.0),
Some(visible_rect),
);
}
if rect.width >= 12.0 && rect.height >= 8.0 {
let center_x = rect.x + rect.width - style.border.right - 8.0;
let center_y = rect.y + rect.height / 2.0;
let mut arrow = PathBuilder::new();
arrow.move_to(center_x - 3.5, center_y - 2.0);
arrow.line_to(center_x + 3.5, center_y - 2.0);
arrow.line_to(center_x, center_y + 2.5);
arrow.close();
if let Some(arrow) = arrow.finish() {
let mut arrow_paint = Paint::default();
let color = style.color.unwrap_or([0, 0, 0, 255]);
arrow_paint.set_color(Color::from_rgba8(
color[0], color[1], color[2], color[3],
));
pixmap.fill_path(
&arrow,
&arrow_paint,
FillRule::Winding,
Transform::identity(),
None,
);
}
}
}
// An empty text `<input>`/`<textarea>` shows its `placeholder`
// attribute as muted text; there is no DOM text node for it (it is
// not real content), so paint it directly from the attribute instead
// of going through `paint_text_node`.
if name.local.as_ref() == "input" || name.local.as_ref() == "textarea" {
let has_value = node.get_attribute("value").map(|v| !v.is_empty()).unwrap_or(false);
if !has_value {
if let Some(placeholder) = node.get_attribute("placeholder") {
if !placeholder.is_empty() {
let fsize = style.font_size.unwrap_or(16.0);
let text_x = rect.x + style.padding.left + style.border.left;
let text_y = rect.y + style.padding.top + style.border.top;
draw_text(
&mut pixmap,
placeholder,
text_x,
text_y,
[117, 117, 117, 255],
fsize,
false,
style.font_family.as_deref(),
style.letter_spacing.unwrap_or(0.0),
clip,
);
}
}
}
}
for generated in &generated_after_at[paint_index] {
paint_in_flow_generated_box(
&mut pixmap,
generated,
laid,
&scroll_state,
viewport,
root_font_size,
base_url,
image_cache,
);
}
}
// Inline formatting contexts shaped by cosmic-text (paragraphs, headings,
// cells, labels) draw last, in tree order, so their glyphs sit above the
// box backgrounds/borders painted in the loop above. Each item already
// carries its final origin and clip from `TextEngine::finalize`.
for nid in tree.descendants(tree.document()) {
if svg_subtree_skip.contains(&nid) {
continue;
}
let whole = laid.ifc_items.get(&nid).copied();
let run_items = laid.run_ifc_items.get(&nid).cloned();
if whole.is_none() && run_items.is_none() {
continue;
}
if laid.styles.get(&nid).map(|s| s.effectively_invisible).unwrap_or(false) {
continue;
}
// Shift the shaped glyphs by the same accumulated translate as the
// container's box so text under a transformed ancestor moves with
// it. Computed before the mutable `paint_item` borrow.
let off = scroll_state.translation_for(laid, nid);
if let Some(idx) = whole {
laid.text_engine.paint_item(idx, &mut pixmap, off);
}
// Anonymous inline-run leaves of a mixed block (see
// `build_mixed_block`), pinned to their own boxes at finalize.
if let Some(items) = run_items {
for idx in items {
laid.text_engine.paint_item(idx, &mut pixmap, off);
}
}
}
Some(pixmap)
}
/// Per-capture root-scroll and sticky offsets layered over an immutable
/// document-space [`DomLayout`]. Keeping these deltas out of the layout avoids
/// accumulating movement when the same prepared document paints more than one
/// frame.
#[derive(Debug)]
struct ScrollPaintState<'a> {
scroll: (f32, f32),
viewport_fixed: &'a std::collections::HashSet<obscura_dom::tree::NodeId>,
sticky: std::collections::HashMap<obscura_dom::tree::NodeId, (f32, f32)>,
sticky_clips: std::collections::HashMap<obscura_dom::tree::NodeId, (f32, f32)>,
active: bool,
}
impl<'a> ScrollPaintState<'a> {
fn new(
viewport: (f32, f32),
requested: (f32, f32),
content: (f32, f32),
viewport_fixed: &'a std::collections::HashSet<obscura_dom::tree::NodeId>,
sticky_layout: &crate::StickyLayout,
) -> Self {
let scroll_x = if requested.0.is_finite() {
requested
.0
.clamp(0.0, (content.0 - viewport.0).max(0.0))
} else {
0.0
};
let scroll_y = if requested.1.is_finite() {
requested
.1
.clamp(0.0, (content.1 - viewport.1).max(0.0))
} else {
0.0
};
let scroll = (scroll_x, scroll_y);
let active = scroll != (0.0, 0.0) || !sticky_layout.is_empty();
if !active {
return Self {
scroll,
viewport_fixed,
sticky: std::collections::HashMap::new(),
sticky_clips: std::collections::HashMap::new(),
active,
};
}
let sticky = sticky_layout.translations(viewport, scroll);
let sticky_clips = sticky_layout.clip_translations_from(&sticky);
Self {
scroll,
viewport_fixed,
sticky,
sticky_clips,
active,
}
}
fn translation_for(
&self,
laid: &crate::DomLayout,
id: obscura_dom::tree::NodeId,
) -> (f32, f32) {
let base = laid.translates.get(&id).copied().unwrap_or((0.0, 0.0));
if !self.active || self.viewport_fixed.contains(&id) {
return base;
}
let sticky = self.sticky.get(&id).copied().unwrap_or((0.0, 0.0));
(
base.0 + sticky.0 - self.scroll.0,
base.1 + sticky.1 - self.scroll.1,
)
}
fn clip_for(
&self,
laid: &crate::DomLayout,
id: obscura_dom::tree::NodeId,
) -> Option<crate::Rect> {
let mut clip = laid.clip_rects.get(&id).copied().flatten()?;
if !self.active || self.viewport_fixed.contains(&id) {
return Some(clip);
}
let sticky = self
.sticky_clips
.get(&id)
.copied()
.unwrap_or((0.0, 0.0));
clip.x += sticky.0 - self.scroll.0;
clip.y += sticky.1 - self.scroll.1;
Some(clip)
}
}
#[derive(Clone, Copy, Debug)]
struct ImageAffine {
a: f32,
b: f32,
c: f32,
d: f32,
e: f32,
f: f32,
}
impl ImageAffine {
const IDENTITY: Self = Self {
a: 1.0,
b: 0.0,
c: 0.0,
d: 1.0,
e: 0.0,
f: 0.0,
};
/// Compose `self(other(point))`.
fn then(self, other: Self) -> Self {
Self {
a: self.a * other.a + self.c * other.b,
b: self.b * other.a + self.d * other.b,
c: self.a * other.c + self.c * other.d,
d: self.b * other.c + self.d * other.d,
e: self.a * other.e + self.c * other.f + self.e,
f: self.b * other.e + self.d * other.f + self.f,
}
}
fn around(origin: (f32, f32), linear: [f32; 4]) -> Self {
let [a, b, c, d] = linear;
Self {
a,
b,
c,
d,
e: origin.0 - a * origin.0 - c * origin.1,
f: origin.1 - b * origin.0 - d * origin.1,
}
}
fn map(self, x: f32, y: f32) -> (f32, f32) {
(
self.a * x + self.c * y + self.e,
self.b * x + self.d * y + self.f,
)
}
fn map_rect(self, rect: crate::Rect) -> crate::Rect {
let points = [
self.map(rect.x, rect.y),
self.map(rect.x + rect.width, rect.y),
self.map(rect.x, rect.y + rect.height),
self.map(rect.x + rect.width, rect.y + rect.height),
];
let left = points.iter().map(|point| point.0).fold(f32::INFINITY, f32::min);
let top = points.iter().map(|point| point.1).fold(f32::INFINITY, f32::min);
let right = points
.iter()
.map(|point| point.0)
.fold(f32::NEG_INFINITY, f32::max);
let bottom = points
.iter()
.map(|point| point.1)
.fold(f32::NEG_INFINITY, f32::max);
crate::Rect {
x: left,
y: top,
width: (right - left).max(0.0),
height: (bottom - top).max(0.0),
}
}
fn tiny_skia(self) -> Transform {
Transform::from_row(self.a, self.b, self.c, self.d, self.e, self.f)
}
fn is_identity(self) -> bool {
(self.a - 1.0).abs() < f32::EPSILON
&& self.b.abs() < f32::EPSILON
&& self.c.abs() < f32::EPSILON
&& (self.d - 1.0).abs() < f32::EPSILON
&& self.e.abs() < f32::EPSILON
&& self.f.abs() < f32::EPSILON
}
}
/// Accumulate rotation/scale matrices through transformed subtrees, storing
/// entries only for raster `<img>` descendants. Translation comes from the
/// per-shot visual state so the document-space layout remains reusable.
fn collect_projected_image_transforms(
tree: &DomTree,
layout: &crate::DomLayout,
scroll_state: &ScrollPaintState,
) -> std::collections::HashMap<obscura_dom::tree::NodeId, ImageAffine> {
if !layout.styles.values().any(|style| {
style.transform_projection.is_some() || style.transform_scale.is_some()
}) {
return std::collections::HashMap::new();
}
fn walk(
tree: &DomTree,
layout: &crate::DomLayout,
scroll_state: &ScrollPaintState,
id: obscura_dom::tree::NodeId,
parent: ImageAffine,
active: bool,
out: &mut std::collections::HashMap<obscura_dom::tree::NodeId, ImageAffine>,
) {
let style = layout.styles.get(&id);
let own_active = style.is_some_and(|style| {
style.transform_projection.is_some() || style.transform_scale.is_some()
});
let mut combined = parent;
if own_active {
let style = style.unwrap();
let projection = style
.transform_projection
.unwrap_or([1.0, 0.0, 0.0, 1.0]);
let (scale_x, scale_y) = style.transform_scale.unwrap_or((1.0, 1.0));
let linear = [
scale_x * projection[0],
scale_y * projection[1],
scale_x * projection[2],
scale_y * projection[3],
];
if let Some(rect) = layout.rects.get(&id) {
let offset = scroll_state.translation_for(layout, id);
let (origin_x, origin_y) = style.transform_origin.unwrap_or((
crate::Dimension::Percent(0.5),
crate::Dimension::Percent(0.5),
));
let origin = (
rect.x + offset.0 + crate::dom::resolve_translate(origin_x, rect.width),
rect.y + offset.1 + crate::dom::resolve_translate(origin_y, rect.height),
);
combined = parent.then(ImageAffine::around(origin, linear));
}
}
let transformed = active || own_active;
if transformed
&& !combined.is_identity()
&& tree.get_node(id).is_some_and(|node| {
node.as_element()
.is_some_and(|element| element.local.as_ref() == "img")
})
{
out.insert(id, combined);
}
for child in tree.children(id) {
walk(
tree,
layout,
scroll_state,
child,
combined,
transformed,
out,
);
}
}
let mut out = std::collections::HashMap::new();
walk(
tree,
layout,
scroll_state,
tree.document(),
ImageAffine::IDENTITY,
false,
&mut out,
);
out
}
/// A closed rounded-rectangle path, corners approximated by quadratic curves
/// (visually indistinguishable from true arcs at typical UI radii). `r` is
/// clamped so it never exceeds half the shorter side.
fn rounded_rect_path(x: f32, y: f32, w: f32, h: f32, r: f32) -> Option<tiny_skia::Path> {
if w <= 0.0 || h <= 0.0 {
return None;
}
let r = r.min(w / 2.0).min(h / 2.0).max(0.0);
let mut pb = PathBuilder::new();
pb.move_to(x + r, y);
pb.line_to(x + w - r, y);
pb.quad_to(x + w, y, x + w, y + r);
pb.line_to(x + w, y + h - r);
pb.quad_to(x + w, y + h, x + w - r, y + h);
pb.line_to(x + r, y + h);
pb.quad_to(x, y + h, x, y + h - r);
pb.line_to(x, y + r);
pb.quad_to(x, y, x + r, y);
pb.close();
pb.finish()
}
/// Paint an outset `box-shadow` layer behind the element's own box. `rect` is
/// the element's (translate-adjusted) border box; the shadow is that box offset
/// by (offset_x, offset_y), expanded by `spread`, with a `blur`-wide soft edge.
/// tiny-skia has no gaussian blur, so the blur is approximated by nested
/// rounded rects from a solid core out to the blur radius, each at a fraction of
/// the shadow alpha so source-over accumulation ramps the coverage from full at
/// the core to near-zero at the outer edge. `inset` shadows are parsed but not
/// painted (an inner shadow needs a hole-punched fill this box model does not
/// build). `clip`, when set, is the ancestor `overflow: hidden` region and is
/// applied as a mask so the shadow is clipped like the element itself.
fn paint_box_shadow(
pixmap: &mut Pixmap,
shadow: &crate::BoxShadow,
rect: &crate::Rect,
border_radius: f32,
clip: Option<crate::Rect>,
) {
if shadow.inset || shadow.color[3] == 0 {
return;
}
let spread = shadow.spread;
let x0 = rect.x + shadow.offset_x - spread;
let y0 = rect.y + shadow.offset_y - spread;
let w0 = rect.width + 2.0 * spread;
let h0 = rect.height + 2.0 * spread;
if w0 <= 0.0 || h0 <= 0.0 {
return;
}
let r0 = (border_radius + spread).max(0.0);
let blur = shadow.blur.max(0.0);
// Ancestor overflow clip: build a mask once and reuse it for every layer.
let mask = match clip {
Some(c) => {
if c.width <= 0.0 || c.height <= 0.0 {
return;
}
box_clip_mask(pixmap.width(), pixmap.height(), &c)
}
None => None,
};
let color = shadow.color;
if blur < 0.5 {
// No blur: a single crisp, offset (and spread) rounded rect.
fill_shadow_rect(pixmap, x0, y0, w0, h0, r0, color, mask.as_ref());
return;
}
let steps: u32 = (blur.ceil() as u32).clamp(2, 24);
// Per-layer alpha chosen so `steps` source-over composites reach the target
// alpha at the core: 1 - (1 - a)^steps == A => a = 1 - (1 - A)^(1/steps).
let a_frac = color[3] as f32 / 255.0;
let per = 1.0 - (1.0 - a_frac).powf(1.0 / steps as f32);
let layer_alpha = (per * 255.0).round().clamp(1.0, 255.0) as u8;
let layer_color = [color[0], color[1], color[2], layer_alpha];
for j in 0..steps {
// j = 0 is the solid core (expansion 0); j = steps-1 reaches the blur
// radius. Larger rects paint first, smaller (more-covered) ones on top.
let e = blur * (j as f32) / ((steps - 1) as f32);
fill_shadow_rect(pixmap, x0 - e, y0 - e, w0 + 2.0 * e, h0 + 2.0 * e, r0 + e, layer_color, mask.as_ref());
}
}
/// Fill one (possibly rounded) shadow rectangle with a flat color, optionally
/// masked to an ancestor clip region. A helper for `paint_box_shadow`'s layers.
fn fill_shadow_rect(
pixmap: &mut Pixmap,
x: f32,
y: f32,
w: f32,
h: f32,
radius: f32,
color: [u8; 4],
mask: Option<&tiny_skia::Mask>,
) {
if w <= 0.0 || h <= 0.0 || color[3] == 0 {
return;
}
let path = if radius > 0.5 {
match rounded_rect_path(x, y, w, h, radius) {
Some(p) => p,
None => return,
}
} else {
let r = match Rect::from_xywh(x, y, w, h) {
Some(r) => r,
None => return,
};
let mut pb = PathBuilder::new();
pb.push_rect(r);
match pb.finish() {
Some(p) => p,
None => return,
}
};
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(color[0], color[1], color[2], color[3]));
paint.anti_alias = true;
pixmap.fill_path(&path, &paint, FillRule::Winding, Transform::identity(), mask);
}
/// The marker text for a list item, or `None` when markers are suppressed
/// (`list-style: none`). `Decimal` numbers the item by its position among
/// sibling list items so `<ol>`s count 1, 2, 3.
fn list_marker_text(tree: &DomTree, nid: obscura_dom::tree::NodeId, style: Option<crate::ListStyle>) -> Option<String> {
match style {
Some(crate::ListStyle::Disc) => Some("\u{2022}".to_string()),
Some(crate::ListStyle::Circle) => Some("\u{25E6}".to_string()),
Some(crate::ListStyle::Square) => Some("\u{25AA}".to_string()),
Some(crate::ListStyle::Decimal) => {
let mut n = 1usize;
let mut cur = tree.get_node(nid).and_then(|node| node.prev_sibling);
while let Some(sib) = cur {
if tree.get_node(sib).and_then(|s| s.as_element().map(|e| e.local.to_string())).as_deref() == Some("li") {
n += 1;
}
cur = tree.get_node(sib).and_then(|s| s.prev_sibling);
}
Some(format!("{}.", n))
}
Some(crate::ListStyle::None) | None => None,
}
}
fn selected_option_label(
tree: &DomTree,
select: obscura_dom::tree::NodeId,
) -> Option<String> {
let mut first = None;
for option_id in tree.descendants(select) {
let Some(option) = tree.get_node(option_id) else { continue };
if option
.as_element()
.map_or(true, |name| name.local.as_ref() != "option")
{
continue;
}
let label = option
.get_attribute("label")
.map(str::to_owned)
.unwrap_or_else(|| tree.text_content(option_id).trim().to_string());
if first.is_none() {
first = Some(label.clone());
}
if option.get_attribute("selected").is_some() {
return Some(label);
}
}
first
}
/// Render `tree` at `viewport` to PNG bytes (RGBA 8-bit). Returns None if the
/// viewport is zero-sized. Convenience over `paint_dom` + `encode_png`.
pub fn screenshot_png(tree: &DomTree, viewport: (f32, f32), base_url: Option<&str>) -> Option<Vec<u8>> {
paint_dom(tree, viewport, base_url)?.encode_png().ok()
}
/// PNG convenience wrapper for a scrolled root viewport.
pub fn screenshot_png_scrolled(
tree: &DomTree,
viewport: (f32, f32),
base_url: Option<&str>,
scroll: (f32, f32),
) -> Option<Vec<u8>> {
paint_dom_scrolled(tree, viewport, base_url, scroll)
.and_then(|pixmap| pixmap.encode_png().ok())
}
/// PNG convenience wrapper for a retained resource-aware layout.
pub fn screenshot_prepared(
tree: &DomTree,
prepared: &mut PreparedRender,
resources: &mut RenderResourceCache,
scroll: (f32, f32),
) -> Option<Vec<u8>> {
paint_prepared(tree, prepared, resources, scroll)?
.encode_png()
.ok()
}
/// A representative visible color for `background-clip: text` text whose own
/// color is transparent, used on the word-split paint path (the cosmic-text IFC
/// path samples the gradient per glyph in `inline`). Returns the gradient's mid
/// stop or the background color so a transparent-colored label still paints;
/// `None` when the element is not a transparent-text clip-to-text box.
fn clip_text_fill_color(style: &crate::LayoutStyle) -> Option<[u8; 4]> {
if !style.background_clip_text {
return None;
}
if style.color.map(|c| c[3] != 0).unwrap_or(true) {
return None;
}
if let Some((_, stops)) = &style.background_gradient {
if !stops.is_empty() {
let mid = stops[stops.len() / 2].0;
return Some([mid[0], mid[1], mid[2], 255]);
}
}
style.background_color.filter(|c| c[3] != 0).map(|c| [c[0], c[1], c[2], 255])
}
/// Paint every word of a text node at its own laid-out position. A text node
/// lays out as one taffy leaf per word (see `dom::build_text_words`), each
/// wrapping independently, so its content is a list of (box, word) pairs
/// rather than one box for the whole node; color/font/clip come from the
/// parent element and are the same for every word.
fn paint_text_node(
tree: &DomTree,
nid: obscura_dom::tree::NodeId,
laid: &crate::DomLayout,
scroll_state: &ScrollPaintState,
pixmap: &mut Pixmap,
) -> Option<()> {
let runs = laid.text_runs.get(&nid)?;
let node = tree.get_node(nid)?;
let parent = node.parent?;
let style = laid.styles.get(&parent)?;
if style.effectively_invisible {
return Some(());
}
let color = clip_text_fill_color(style).unwrap_or_else(|| style.color.unwrap_or([0, 0, 0, 255]));
let fsize = style.font_size.unwrap_or(16.0);
let is_bold = crate::style::used_font_weight(style) >= 600;
// A text node has no transform of its own, but any transformed element
// ancestor offsets it (the accumulation covers text nodes too). The clip
// receives root-scroll/sticky movement without following the descendant's
// own transform.
let (ox, oy) = scroll_state.translation_for(laid, nid);
let clip = scroll_state.clip_for(laid, nid);
for (rect, word) in runs {
draw_text(
pixmap,
word,
rect.x + ox,
rect.y + oy,
color,
fsize,
is_bold,
style.font_family.as_deref(),
style.letter_spacing.unwrap_or(0.0),
clip,
);
}
Some(())
}
fn fallback_font_bytes(family: Option<&str>) -> &'static [u8] {
let Some(family) = family else { return FONT_BYTES };
for token in family.split(',') {
let token = token
.trim()
.trim_matches(|c| c == '"' || c == '\'')
.to_ascii_lowercase();
if token == "monospace"
|| token.contains("mono")
|| token.contains("courier")
|| token.contains("consol")
|| token == "menlo"
|| token == "monaco"
|| token == "code"
{
return MONO_FONT_BYTES;
}
if token == "serif"
|| token == "georgia"
|| token.contains("times")
|| token == "cambria"
|| token.contains("garamond")
|| token.contains("liberation serif")
|| token == "roman"
{
return SERIF_FONT_BYTES;
}
if token == "sans-serif"
|| token.contains("sans")
|| token == "arial"
|| token == "helvetica"
|| token == "helvetica neue"
|| token == "system-ui"
|| token == "-apple-system"
|| token == "roboto"
|| token == "segoe ui"
|| token == "inter"
|| token == "verdana"
|| token == "tahoma"
|| token == "ui-sans-serif"
{
return FONT_BYTES;
}
}
FONT_BYTES
}
pub fn measure_text(text: &str, size: f32, is_bold: bool, family: Option<&str>) -> f32 {
let font = FontRef::try_from_slice(fallback_font_bytes(family)).unwrap();
let scale = PxScale::from(size);
let scaled_font = font.as_scaled(scale);
let mut width = 0.0;
for c in text.chars() {
if c.is_control() { continue; }
width += scaled_font.h_advance(font.glyph_id(c));
}
if is_bold { width += text.chars().filter(|c| !c.is_control()).count() as f32; }
width
}
fn draw_text(
pixmap: &mut Pixmap,
text: &str,
x: f32,
y: f32,
color: [u8; 4],
size: f32,
is_bold: bool,
family: Option<&str>,
letter_spacing: f32,
clip: Option<crate::Rect>,
) {
// A fully clipped-away run (the common "visually hidden" accessibility
// pattern: a 1x1 box with overflow: hidden) paints nothing at all.
if let Some(c) = clip {
if c.width <= 0.0 || c.height <= 0.0 {
return;
}
}
let font = FontRef::try_from_slice(fallback_font_bytes(family)).unwrap();
let scale = PxScale::from(size);
let scaled_font = font.as_scaled(scale);
let mut caret = ab_glyph::point(x, y + scaled_font.ascent());
let width = pixmap.width() as i32;
let height = pixmap.height() as i32;
let clip_bounds = clip.map(|c| (c.x, c.y, c.x + c.width, c.y + c.height));
let pixels = pixmap.pixels_mut();
let (r, g, b, a_full) = (color[0], color[1], color[2], color[3]);
for c in text.chars() {
if c.is_control() {
continue;
}
let glyph_id = font.glyph_id(c);
let id = glyph_id;
let glyph = glyph_id.with_scale_and_position(scale, caret);
if let Some(outlined) = font.outline_glyph(glyph) {
let bounds = outlined.px_bounds();
outlined.draw(|gx, gy, c| {
let px = (bounds.min.x + gx as f32) as i32;
let py = (bounds.min.y + gy as f32) as i32;
if let Some((cx0, cy0, cx1, cy1)) = clip_bounds {
if (px as f32) < cx0 || (px as f32) >= cx1 || (py as f32) < cy0 || (py as f32) >= cy1 {
return;
}
}
if px >= 0 && px < width && py >= 0 && py < height {
let alpha = (a_full as f32 * c) as u8;
if alpha > 0 {
let mut px_indices = vec![(py * width + px) as usize];
if is_bold && px + 1 < width {
px_indices.push((py * width + px + 1) as usize);
}
for idx in px_indices {
let dst = pixels[idx];
let src_a = alpha as u32;
let src_r = (r as u32 * src_a) / 255;
let src_g = (g as u32 * src_a) / 255;
let src_b = (b as u32 * src_a) / 255;
let dst_a = dst.alpha() as u32;
let out_a = src_a + (dst_a * (255 - src_a) / 255);
if out_a > 0 {
let out_r = src_r + (dst.red() as u32 * (255 - src_a) / 255);
let out_g = src_g + (dst.green() as u32 * (255 - src_a) / 255);
let out_b = src_b + (dst.blue() as u32 * (255 - src_a) / 255);
pixels[idx] = tiny_skia::PremultipliedColorU8::from_rgba(
out_r as u8, out_g as u8, out_b as u8, out_a as u8
).unwrap_or_else(|| tiny_skia::PremultipliedColorU8::from_rgba(0,0,0,0).unwrap());
}
}
}
}
});
// Matches measure_text's +1px-per-character bold compensation:
// without it, a word's reserved layout width (from measure_text)
// is wider than what draw_text actually advances through, and
// the difference shows up as a visible gap after every word once
// each word is its own independently-positioned box.
caret.x += scaled_font.h_advance(id)
+ if is_bold { 1.0 } else { 0.0 }
+ letter_spacing;
} else {
caret.x += scaled_font.h_advance(id)
+ if is_bold { 1.0 } else { 0.0 }
+ letter_spacing;
}
}
}
/// Resolve `src` (a `data:` URI, or an absolute/relative URL against
/// `base_url`) to raw bytes, fetching over the network at most once per
/// distinct URL through the retained resource cache.
fn fetch_bytes(
src: &str,
base_url: Option<&str>,
cache: &mut RenderResourceCache,
) -> Option<Arc<[u8]>> {
if let Some(rest) = src.strip_prefix("data:") {
let comma_idx = rest.find(',')?;
let (meta, data) = (&rest[..comma_idx], &rest[comma_idx + 1..]);
// Data-backed SVGs and web fonts may be base64 or percent-escaped.
// Decode from the encoding label rather than assuming every data URI
// is base64.
let bytes = if meta.contains("base64") {
use base64::Engine;
base64::engine::general_purpose::STANDARD.decode(data).ok()
} else {
Some(percent_decode(data))
}?;
return Some(Arc::from(bytes));
}
let resolved = resolve_resource_url(src, base_url)?;
cache.get_or_load(&resolved)
}
fn resolve_resource_url(src: &str, base_url: Option<&str>) -> Option<String> {
if src.starts_with("data:") {
return Some(src.to_string());
}
// Resolve relative to the document's base URL: the overwhelming majority
// of real markup uses relative image paths ("logo.svg", not
// "https://example.com/logo.svg"), so without this every relative <img>
// or mask/background reference silently fails to fetch.
if src.starts_with("http://") || src.starts_with("https://") {
Some(src.to_string())
} else if let Some(rest) = src.strip_prefix("//") {
// Protocol-relative URL (`//upload.wikimedia.org/...`, ubiquitous on
// Wikipedia and CDN-hosted media): inherit the document scheme, but
// never `file:`/other non-network schemes (a `file://` base would give
// `file://host/...` and fail), so default to https for those.
let scheme = base_url
.and_then(|b| url::Url::parse(b).ok())
.map(|u| u.scheme().to_string())
.filter(|s| s == "http" || s == "https")
.unwrap_or_else(|| "https".to_string());
Some(format!("{scheme}://{rest}"))
} else {
base_url
.and_then(|b| url::Url::parse(b).ok())
.and_then(|base| base.join(src).ok())
.map(|u| u.to_string())
}
}
/// Fetch the Latin/ASCII face from each authored `@font-face` rule and decode
/// WOFF/WOFF2 into the sfnt bytes consumed by fontdb/cosmic-text. Unicode-range
/// filtering is load-bearing for performance: generated font packages commonly
/// emit six or seven script subsets per face, while an English page needs only
/// the subset containing ASCII.
fn collect_web_fonts(
tree: &DomTree,
base_url: Option<&str>,
cache: &mut RenderResourceCache,
) -> Vec<crate::inline::WebFont> {
let mut seen = std::collections::HashSet::new();
let mut fonts = Vec::new();
let mut rules = Vec::new();
for nid in tree.descendants(tree.document()) {
let Some(node) = tree.get_node(nid) else { continue };
if node
.as_element()
.map(|element| element.local.as_ref() != "style")
.unwrap_or(true)
{
continue;
}
let css = tree.text_content(nid);
for face in font_face_blocks(&css) {
if !font_face_covers_ascii(face) {
continue;
}
let Some(src) = font_face_urls(face).into_iter().next() else {
continue;
};
rules.push((
font_resource_key(&src, base_url),
src,
font_face_family(face),
font_face_weight(face),
font_face_italic(face),
));
}
}
// Critical web fonts are normally preloaded from the document with a URL
// already resolved relative to the HTML. Fetch those first, while retaining
// the matching @font-face descriptors needed for CSS family/weight lookup.
let mut preloads = Vec::new();
for nid in tree.descendants(tree.document()) {
let Some(node) = tree.get_node(nid) else { continue };
if node
.as_element()
.map(|element| element.local.as_ref() != "link")
.unwrap_or(true)
{
continue;
}
let rel = node.get_attribute("rel").unwrap_or("");
let as_value = node.get_attribute("as").unwrap_or("");
if rel
.split_ascii_whitespace()
.any(|token| token.eq_ignore_ascii_case("preload"))
&& as_value.eq_ignore_ascii_case("font")
{
if let Some(href) = node.get_attribute("href") {
preloads.push(href.to_string());
}
}
}
for src in preloads.iter().take(16) {
let key = font_resource_key(src, base_url);
if !seen.insert(key.clone()) {
continue;
}
if let Some(decoded) = fetch_and_decode_font(src, base_url, cache) {
let metadata = rules.iter().find(|rule| rule.0 == key);
fonts.push(crate::inline::WebFont {
data: decoded,
family: metadata.and_then(|rule| rule.2.clone()),
weight: metadata.and_then(|rule| rule.3),
italic: metadata.and_then(|rule| rule.4),
});
}
}
for (key, src, family, weight, italic) in rules {
if fonts.len() >= 16 {
break;
}
if !seen.insert(key) {
continue;
}
if let Some(decoded) = fetch_and_decode_font(&src, base_url, cache) {
fonts.push(crate::inline::WebFont {
data: decoded,
family,
weight,
italic,
});
}
}
fonts
}
fn font_resource_key(src: &str, base_url: Option<&str>) -> String {
url::Url::parse(src)
.ok()
.or_else(|| {
base_url
.and_then(|base| url::Url::parse(base).ok())
.and_then(|base| base.join(src).ok())
})
.map(|url| url.to_string())
.unwrap_or_else(|| src.to_string())
}
fn fetch_and_decode_font(
src: &str,
base_url: Option<&str>,
cache: &mut RenderResourceCache,
) -> Option<Vec<u8>> {
let compressed = fetch_bytes(src, base_url, cache)?;
if compressed.len() > 8 * 1024 * 1024 {
return None;
}
let decoded = match compressed.get(..4) {
Some(b"wOF2") => wuff::decompress_woff2(&compressed).ok(),
Some(b"wOFF") => wuff::decompress_woff1(&compressed).ok(),
// TrueType/OpenType collections and raw sfnt fonts already have the
// representation fontdb expects.
Some(b"\0\x01\0\0" | b"OTTO" | b"ttcf") => Some(compressed.as_ref().to_vec()),
_ => None,
}?;
(decoded.len() <= 32 * 1024 * 1024).then_some(decoded)
}
fn font_face_blocks(css: &str) -> Vec<&str> {
let lower = css.to_ascii_lowercase();
let mut out = Vec::new();
let mut cursor = 0;
while let Some(relative) = lower[cursor..].find("@font-face") {
let at = cursor + relative;
let Some(open_relative) = lower[at..].find('{') else {
break;
};
let open = at + open_relative;
let mut depth = 1i32;
let mut quote = None;
let mut escaped = false;
let mut close = None;
for (offset, ch) in css[open + 1..].char_indices() {
if escaped {
escaped = false;
continue;
}
if ch == '\\' {
escaped = true;
continue;
}
if let Some(active) = quote {
if ch == active {
quote = None;
}
continue;
}
if matches!(ch, '"' | '\'') {
quote = Some(ch);
continue;
}
match ch {
'{' => depth += 1,
'}' => {
depth -= 1;
if depth == 0 {
close = Some(open + 1 + offset);
break;
}
}
_ => {}
}
}
let Some(close) = close else { break };
out.push(&css[open + 1..close]);
cursor = close + 1;
}
out
}
fn font_face_declaration<'a>(face: &'a str, name: &str) -> Option<&'a str> {
split_css_top_level(face, ';').into_iter().find_map(|declaration| {
let (property, value) = declaration.split_once(':')?;
property.trim().eq_ignore_ascii_case(name).then_some(value.trim())
})
}
fn font_face_family(face: &str) -> Option<String> {
font_face_declaration(face, "font-family")
.map(|family| family.trim().trim_matches(|ch| matches!(ch, '"' | '\'')).to_string())
.filter(|family| !family.is_empty())
}
fn font_face_weight(face: &str) -> Option<(u16, u16)> {
fn parse(value: &str) -> Option<u16> {
match value.to_ascii_lowercase().as_str() {
"normal" => Some(400),
"bold" => Some(700),
value => value
.parse::<f32>()
.ok()
.filter(|weight| weight.is_finite() && (1.0..=1000.0).contains(weight))
.map(|weight| weight.round() as u16),
}
}
let mut values = font_face_declaration(face, "font-weight")?
.split_ascii_whitespace()
.filter_map(parse);
let first = values.next()?;
let second = values.next().unwrap_or(first);
Some((first.min(second), first.max(second)))
}
fn font_face_italic(face: &str) -> Option<bool> {
font_face_declaration(face, "font-style").and_then(|style| {
let style = style.trim().to_ascii_lowercase();
if style == "normal" {
Some(false)
} else if style == "italic" || style.starts_with("oblique") {
Some(true)
} else {
None
}
})
}
fn font_face_covers_ascii(face: &str) -> bool {
let Some(range) = font_face_declaration(face, "unicode-range") else {
return true;
};
range.split(',').any(|part| {
let token = part.trim().to_ascii_lowercase();
let Some(value) = token.strip_prefix("u+") else {
return false;
};
let (start, end) = if value.contains('?') {
(
u32::from_str_radix(&value.replace('?', "0"), 16).ok(),
u32::from_str_radix(&value.replace('?', "f"), 16).ok(),
)
} else if let Some((start, end)) = value.split_once('-') {
(
u32::from_str_radix(start, 16).ok(),
u32::from_str_radix(end, 16).ok(),
)
} else {
let point = u32::from_str_radix(value, 16).ok();
(point, point)
};
matches!((start, end), (Some(start), Some(end)) if start <= 0x7e && end >= 0x20)
})
}
fn font_face_urls(face: &str) -> Vec<String> {
let Some(src) = font_face_declaration(face, "src") else {
return Vec::new();
};
let lower = src.to_ascii_lowercase();
let mut out = Vec::new();
let mut cursor = 0;
while let Some(relative) = lower[cursor..].find("url(") {
let start = cursor + relative + 4;
let Some(end_relative) = src[start..].find(')') else {
break;
};
let end = start + end_relative;
let value = src[start..end]
.trim()
.trim_matches(|ch| ch == '"' || ch == '\'')
.trim();
if !value.is_empty() {
out.push(value.to_string());
}
cursor = end + 1;
}
out
}
fn split_css_top_level(value: &str, separator: char) -> Vec<&str> {
let mut out = Vec::new();
let mut start = 0;
let mut depth = 0i32;
let mut quote = None;
let mut escaped = false;
for (index, ch) in value.char_indices() {
if escaped {
escaped = false;
continue;
}
if ch == '\\' {
escaped = true;
continue;
}
if let Some(active) = quote {
if ch == active {
quote = None;
}
continue;
}
if matches!(ch, '"' | '\'') {
quote = Some(ch);
continue;
}
match ch {
'(' => depth += 1,
')' => depth = (depth - 1).max(0),
ch if ch == separator && depth == 0 => {
out.push(&value[start..index]);
start = index + ch.len_utf8();
}
_ => {}
}
}
out.push(&value[start..]);
out
}
/// Fetch `url` with a descriptive User-Agent and a bounded timeout, retrying on
/// rate-limit / transient errors with backoff. Real pages pull dozens of images
/// from one CDN in a burst (a Wikipedia article references ~60); hosts like
/// Wikimedia answer a rapid burst with HTTP 429 after ~10 requests. Without a
/// retry the rate-limited images (e.g. an infobox photo montage fetched late in
/// the burst) came back blank, and the failure was cached permanently. The
/// backoff both recovers them and paces the burst back under the limit.
fn http_get_bytes(url: &str) -> Option<Vec<u8>> {
let mut backoff = std::time::Duration::from_millis(200);
for attempt in 0..3 {
// A browser-like Accept advertises the modern image formats and is what
// content-negotiating CDNs expect; some UA-gated hosts also reject a
// request with no Accept header outright.
let res = image_agent()
.get(url)
.set("Accept", "image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8")
.call();
match res {
Ok(resp) => {
let mut buf = Vec::new();
use std::io::Read;
return resp.into_reader().read_to_end(&mut buf).ok().map(|_| buf);
}
// 429 (rate limit) and 5xx are transient: a short backoff clears a
// brief blip. A sustained limit (Wikimedia 429s a 60-image burst
// from a datacenter IP hard, with `Retry-After: 1`) is NOT worth
// waiting out here: honoring the hint stalls the whole render for
// minutes, so fast-fail to the grey placeholder instead. Real
// fidelity for that case needs an HTTP/2 image client (multiplexing
// like Chrome), not blocking retries.
Err(ureq::Error::Status(code, _)) if matches!(code, 429 | 500 | 502 | 503 | 504) && attempt < 2 => {
std::thread::sleep(backoff);
backoff *= 2;
}
Err(ureq::Error::Transport(_)) if attempt < 2 => {
std::thread::sleep(backoff);
backoff *= 2;
}
Err(_) => return None,
}
}
None
}
/// One shared HTTP agent for all image fetches in the process, with a browser
/// User-Agent and keep-alive connection pooling. A CDN's bot rate-limiter keys
/// on connection churn as much as on rate: a fresh TLS handshake per image (the
/// old per-call `ureq::get`) reads as a burst and gets 429'd, whereas reusing
/// one pooled connection to the same host (as a browser does) both avoids most
/// throttling and is much faster on an image-heavy page.
fn image_agent() -> &'static ureq::Agent {
static AGENT: std::sync::OnceLock<ureq::Agent> = std::sync::OnceLock::new();
AGENT.get_or_init(|| {
ureq::AgentBuilder::new()
.timeout(std::time::Duration::from_secs(10))
// Present the same normal browser identity the engine uses for the
// document. A bot-identifying UA got image requests filtered by CDNs
// that gate on User-Agent (Akamai/Cloudflare image endpoints on
// cnbc, techcrunch, arstechnica), so the images Chrome loads came
// back blank; a real browser UA loads the same bytes Chrome does.
.user_agent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36")
.build()
})
}
/// Decode a percent-escaped data: URI payload (`%23` -> `#`, etc). Bytes that
/// are not part of a `%XX` escape pass through unchanged, which is exactly
/// right for the inline-SVG case: only the characters that would otherwise be
/// ambiguous in a URI (`#`, `"`, ...) get escaped, everything else is literal
/// UTF-8 text.
fn percent_decode(s: &str) -> Vec<u8> {
// Operates on raw bytes throughout (never slices `s` as a string): a
// stray '%' followed by non-hex bytes could otherwise land a string
// slice in the middle of a multi-byte UTF-8 character and panic.
let bytes = s.as_bytes();
let mut out = Vec::with_capacity(bytes.len());
let mut i = 0;
while i < bytes.len() {
if bytes[i] == b'%' && i + 2 < bytes.len() {
let hi = (bytes[i + 1] as char).to_digit(16);
let lo = (bytes[i + 2] as char).to_digit(16);
if let (Some(hi), Some(lo)) = (hi, lo) {
out.push((hi * 16 + lo) as u8);
i += 3;
continue;
}
}
out.push(bytes[i]);
i += 1;
}
out
}
/// Decode raster image bytes (jpeg/png/webp) to a premultiplied-alpha pixmap
/// resized to `w`x`h`.
fn raster_to_pixmap(bytes: &[u8], w: u32, h: u32) -> Option<Pixmap> {
let img = image::load_from_memory(bytes).ok()?.to_rgba8();
let resized = image::imageops::resize(&img, w, h, image::imageops::FilterType::Triangle);
let mut raw = resized.into_raw();
for pixel in raw.chunks_exact_mut(4) {
let a = pixel[3] as u32;
pixel[0] = ((pixel[0] as u32 * a) / 255) as u8;
pixel[1] = ((pixel[1] as u32 * a) / 255) as u8;
pixel[2] = ((pixel[2] as u32 * a) / 255) as u8;
}
let size = tiny_skia::IntSize::from_wh(w, h)?;
Pixmap::from_vec(raw, size)
}
/// Read an image's intrinsic pixel dimensions from its header only, without
/// decoding the whole thing. Returns None for formats the raster decoder does
/// not recognize (e.g. SVG, which is sized elsewhere).
/// Fill `path` with a CSS `linear-gradient`. `angle` is degrees clockwise from
/// 12 o'clock (0 = to top). The gradient line length uses the CSS formula so
/// the stops land where a browser puts them. Positionless stops are spread
/// evenly; positions are clamped monotonic (tiny-skia requires ascending).
fn paint_linear_gradient(pixmap: &mut Pixmap, path: &tiny_skia::Path, rect: &crate::Rect, angle: f32, stops: &[([u8; 4], Option<f32>)]) {
if stops.len() < 2 {
return;
}
let rad = angle.to_radians();
let dx = rad.sin();
let dy = -rad.cos();
let (cx, cy) = (rect.x + rect.width / 2.0, rect.y + rect.height / 2.0);
let half = (dx.abs() * rect.width + dy.abs() * rect.height) / 2.0;
let start = Point::from_xy(cx - dx * half, cy - dy * half);
let end = Point::from_xy(cx + dx * half, cy + dy * half);
let n = stops.len();
let mut gs: Vec<GradientStop> = Vec::with_capacity(n);
let mut last = 0.0f32;
for (i, (_, pos)) in stops.iter().enumerate() {
let c = gradient_stop_color(stops, i);
let p = pos.unwrap_or(i as f32 / (n - 1) as f32).clamp(0.0, 1.0).max(last);
last = p;
gs.push(GradientStop::new(p, Color::from_rgba8(c[0], c[1], c[2], c[3])));
}
if let Some(shader) = LinearGradient::new(start, end, gs, SpreadMode::Pad, Transform::identity()) {
let mut paint = Paint::default();
paint.shader = shader;
paint.anti_alias = true;
pixmap.fill_path(path, &paint, FillRule::Winding, Transform::identity(), None);
}
}
fn paint_radial_gradient(
pixmap: &mut Pixmap,
path: &tiny_skia::Path,
rect: &crate::Rect,
center: (f32, f32),
stops: &[([u8; 4], Option<f32>)],
) {
if stops.len() < 2 {
return;
}
let center = Point::from_xy(
rect.x + rect.width * center.0,
rect.y + rect.height * center.1,
);
let radius = [
(rect.x - center.x).hypot(rect.y - center.y),
(rect.x + rect.width - center.x).hypot(rect.y - center.y),
(rect.x - center.x).hypot(rect.y + rect.height - center.y),
(rect.x + rect.width - center.x).hypot(rect.y + rect.height - center.y),
]
.into_iter()
.fold(0.0, f32::max);
let normalized = normalized_stops(stops);
let gradient_stops = normalized
.into_iter()
.map(|(position, color)| {
GradientStop::new(
position,
Color::from_rgba8(color[0], color[1], color[2], color[3]),
)
})
.collect();
if let Some(shader) = RadialGradient::new(
center,
0.0,
center,
radius,
gradient_stops,
SpreadMode::Pad,
Transform::identity(),
) {
let mut paint = Paint::default();
paint.shader = shader;
paint.anti_alias = true;
pixmap.fill_path(path, &paint, FillRule::Winding, Transform::identity(), None);
}
}
fn paint_conic_gradient(
pixmap: &mut Pixmap,
rect: &crate::Rect,
angle: f32,
center: (f32, f32),
stops: &[([u8; 4], Option<f32>)],
) {
if rect.width <= 0.0 || rect.height <= 0.0 || stops.len() < 2 {
return;
}
let width = rect.width.ceil() as u32;
let height = rect.height.ceil() as u32;
let Some(mut layer) = Pixmap::new(width, height) else {
return;
};
let normalized = normalized_stops(stops);
for y in 0..height {
for x in 0..width {
let color = conic_color_at(
rect,
angle,
center,
&normalized,
rect.x + x as f32 + 0.5,
rect.y + y as f32 + 0.5,
);
layer.pixels_mut()[(y * width + x) as usize] = premultiplied(color);
}
}
pixmap.draw_pixmap(
rect.x.floor() as i32,
rect.y.floor() as i32,
layer.as_ref(),
&tiny_skia::PixmapPaint::default(),
Transform::identity(),
None,
);
}
fn normalized_stops(
stops: &[([u8; 4], Option<f32>)],
) -> Vec<(f32, [u8; 4])> {
let count = stops.len();
let mut normalized = Vec::with_capacity(count);
let mut last = 0.0f32;
for (index, (_, position)) in stops.iter().enumerate() {
let color = gradient_stop_color(stops, index);
let position = position
.unwrap_or_else(|| {
if count <= 1 {
0.0
} else {
index as f32 / (count - 1) as f32
}
})
.clamp(0.0, 1.0)
.max(last);
last = position;
normalized.push((position, color));
}
normalized
}
fn gradient_stop_color(
stops: &[([u8; 4], Option<f32>)],
index: usize,
) -> [u8; 4] {
let color = stops[index].0;
if color[3] != 0 {
return color;
}
let neighbor = stops[index + 1..]
.iter()
.find(|(candidate, _)| candidate[3] != 0)
.or_else(|| stops[..index].iter().rev().find(|(candidate, _)| candidate[3] != 0));
neighbor
.map(|(neighbor, _)| [neighbor[0], neighbor[1], neighbor[2], 0])
.unwrap_or(color)
}
fn sample_normalized_stops(stops: &[(f32, [u8; 4])], t: f32) -> [u8; 4] {
let t = t.clamp(0.0, 1.0);
let Some(&(first_position, first_color)) = stops.first() else {
return [0, 0, 0, 0];
};
if t <= first_position {
return first_color;
}
for pair in stops.windows(2) {
let (start_position, start_color) = pair[0];
let (end_position, end_color) = pair[1];
if t <= end_position {
let span = end_position - start_position;
let fraction = if span <= f32::EPSILON {
1.0
} else {
((t - start_position) / span).clamp(0.0, 1.0)
};
let interpolate = |start: u8, end: u8| {
(start as f32 + (end as f32 - start as f32) * fraction)
.round()
.clamp(0.0, 255.0) as u8
};
return [
interpolate(start_color[0], end_color[0]),
interpolate(start_color[1], end_color[1]),
interpolate(start_color[2], end_color[2]),
interpolate(start_color[3], end_color[3]),
];
}
}
stops.last().map(|(_, color)| *color).unwrap_or(first_color)
}
fn conic_color_at(
rect: &crate::Rect,
angle: f32,
center: (f32, f32),
stops: &[(f32, [u8; 4])],
x: f32,
y: f32,
) -> [u8; 4] {
let center_x = rect.x + rect.width * center.0;
let center_y = rect.y + rect.height * center.1;
let point_angle = (x - center_x)
.atan2(-(y - center_y))
.to_degrees()
.rem_euclid(360.0);
let position = (point_angle - angle).rem_euclid(360.0) / 360.0;
sample_normalized_stops(stops, position)
}
fn linear_color_at(
rect: &crate::Rect,
angle: f32,
stops: &[(f32, [u8; 4])],
x: f32,
y: f32,
) -> [u8; 4] {
let radians = angle.to_radians();
let dx = radians.sin();
let dy = -radians.cos();
let center_x = rect.x + rect.width / 2.0;
let center_y = rect.y + rect.height / 2.0;
let half = (dx.abs() * rect.width + dy.abs() * rect.height) / 2.0;
if half <= f32::EPSILON {
return sample_normalized_stops(stops, 0.5);
}
let start_x = center_x - dx * half;
let start_y = center_y - dy * half;
let position = ((x - start_x) * dx + (y - start_y) * dy) / (2.0 * half);
sample_normalized_stops(stops, position)
}
fn premultiplied(color: [u8; 4]) -> tiny_skia::PremultipliedColorU8 {
let alpha = color[3] as u32;
tiny_skia::PremultipliedColorU8::from_rgba(
((color[0] as u32 * alpha) / 255) as u8,
((color[1] as u32 * alpha) / 255) as u8,
((color[2] as u32 * alpha) / 255) as u8,
color[3],
)
.unwrap_or_else(|| {
tiny_skia::PremultipliedColorU8::from_rgba(0, 0, 0, 0)
.expect("transparent premultiplied color")
})
}
fn image_dimensions(bytes: &[u8]) -> Option<(u32, u32)> {
image::ImageReader::new(std::io::Cursor::new(bytes))
.with_guessed_format()
.ok()?
.into_dimensions()
.ok()
}
fn image_metadata_from_bytes(bytes: &[u8]) -> Option<(f32, f32)> {
let (width, height) = image_dimensions(bytes)
.map(|(width, height)| (width as f32, height as f32))
.or_else(|| svg_intrinsic(bytes))?;
if !width.is_finite() || !height.is_finite() || width <= 0.0 || height <= 0.0 {
return None;
}
Some((width, height))
}
fn background_image_rect(
src: &str,
base_url: Option<&str>,
box_rect: &crate::Rect,
explicit_size: Option<(f32, f32)>,
size_expression: Option<&str>,
fit: Option<crate::ObjectFit>,
position: (f32, f32),
em: f32,
rem: f32,
viewport: (f32, f32),
cache: &mut RenderResourceCache,
) -> Option<crate::Rect> {
let bytes = fetch_bytes(src, base_url, cache)?;
let intrinsic = if is_svg(&bytes) {
svg_intrinsic(&bytes)
} else {
image_dimensions(&bytes).map(|(width, height)| (width as f32, height as f32))
};
let expression_size = size_expression.and_then(|expression| {
let components = split_background_size_components(expression);
let width = components.first().and_then(|value| {
(!value.eq_ignore_ascii_case("auto")).then(|| {
crate::style::resolve_contextual_length(
value,
em,
rem,
viewport.0 / 100.0,
viewport.1 / 100.0,
box_rect.width,
)
})?
});
let height = components.get(1).and_then(|value| {
(!value.eq_ignore_ascii_case("auto")).then(|| {
crate::style::resolve_contextual_length(
value,
em,
rem,
viewport.0 / 100.0,
viewport.1 / 100.0,
box_rect.height,
)
})?
});
match (width, height, intrinsic) {
(Some(width), Some(height), _) => Some((width, height)),
(Some(width), None, Some((iw, ih))) => Some((width, width * ih / iw)),
(None, Some(height), Some((iw, ih))) => Some((height * iw / ih, height)),
(None, None, Some(intrinsic)) => Some(intrinsic),
_ => None,
}
});
let (width, height) = if let Some(size) = expression_size {
size
} else if let Some(size) = explicit_size {
size
} else if let Some(fit) = fit {
let (iw, ih) = intrinsic?;
let scale = match fit {
crate::ObjectFit::Cover => (box_rect.width / iw).max(box_rect.height / ih),
crate::ObjectFit::Contain => (box_rect.width / iw).min(box_rect.height / ih),
_ => 1.0,
};
(iw * scale, ih * scale)
} else {
intrinsic.unwrap_or((box_rect.width, box_rect.height))
};
if width <= 0.0 || height <= 0.0 {
return None;
}
Some(crate::Rect {
x: box_rect.x + (box_rect.width - width) * position.0,
y: box_rect.y + (box_rect.height - height) * position.1,
width,
height,
})
}
fn split_background_size_components(value: &str) -> Vec<&str> {
let mut components = Vec::new();
let mut depth = 0i32;
let mut start = None;
for (index, ch) in value.char_indices() {
match ch {
'(' => {
depth += 1;
start.get_or_insert(index);
}
')' => depth = (depth - 1).max(0),
ch if ch.is_whitespace() && depth == 0 => {
if let Some(start) = start.take() {
components.push(value[start..index].trim());
}
}
_ => {
start.get_or_insert(index);
}
}
}
if let Some(start) = start {
components.push(value[start..].trim());
}
components
}
fn paint_in_flow_generated_box(
pixmap: &mut Pixmap,
generated: &crate::dom::GeneratedBox,
laid: &crate::dom::DomLayout,
scroll_state: &ScrollPaintState,
viewport: (f32, f32),
root_font_size: f32,
base_url: Option<&str>,
image_cache: &mut RenderResourceCache,
) {
let Some(host_style) = laid.styles.get(&generated.host) else {
return;
};
let style = match generated.kind {
crate::dom::GeneratedBoxKind::Before => host_style.before_pseudo.as_deref(),
crate::dom::GeneratedBoxKind::After => host_style.after_pseudo.as_deref(),
};
let Some(style) = style else { return };
if style.effectively_invisible {
return;
}
let (ox, oy) = scroll_state.translation_for(laid, generated.host);
let rect = crate::Rect {
x: generated.rect.x + ox,
y: generated.rect.y + oy,
width: generated.rect.width,
height: generated.rect.height,
};
let mut clip = scroll_state.clip_for(laid, generated.host);
if host_style.overflow_hidden {
if let Some(host_rect) = laid.rects.get(&generated.host) {
let own = crate::Rect {
x: host_rect.x + ox,
y: host_rect.y + oy,
width: host_rect.width,
height: host_rect.height,
};
clip = Some(match clip {
Some(inherited) => inherited.intersect(&own).unwrap_or(crate::Rect::default()),
None => own,
});
}
}
let visible = match clip {
Some(clip) => rect.intersect(&clip),
None => Some(rect),
};
let Some(visible) = visible else { return };
if visible.width <= 0.0 || visible.height <= 0.0 {
return;
}
if let Some(shadow) = style.box_shadow {
paint_box_shadow(pixmap, &shadow, &rect, style.border_radius, clip);
}
let path = if style.border_radius > 0.5 {
rounded_rect_path(
visible.x,
visible.y,
visible.width,
visible.height,
style.border_radius,
)
} else {
Rect::from_xywh(visible.x, visible.y, visible.width, visible.height).and_then(|rect| {
let mut builder = PathBuilder::new();
builder.push_rect(rect);
builder.finish()
})
};
let Some(path) = path else { return };
if style.mask_image.is_none() && !style.background_clip_text {
if let Some(color) = style.background_color {
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(color[0], color[1], color[2], color[3]));
paint.anti_alias = style.border_radius > 0.5;
pixmap.fill_path(
&path,
&paint,
FillRule::Winding,
Transform::identity(),
None,
);
}
if let Some((center, stops)) = &style.background_radial_gradient {
paint_radial_gradient(pixmap, &path, &rect, *center, stops);
}
if let Some((angle, center, stops)) = &style.background_conic_gradient {
paint_conic_gradient(pixmap, &rect, *angle, *center, stops);
}
if let Some((angle, stops)) = &style.background_gradient {
paint_linear_gradient(pixmap, &path, &rect, *angle, stops);
}
}
if let Some(mask_url) = &style.mask_image {
let fill = style
.background_color
.or(style.color)
.unwrap_or([0, 0, 0, 255]);
paint_mask(
mask_url,
base_url,
&visible,
fill,
style.background_gradient.as_ref(),
style.background_conic_gradient.as_ref(),
style.mask_size,
style.mask_repeat,
pixmap,
image_cache,
);
} else if let Some(background_url) = &style.background_image {
if let Some(image_rect) = background_image_rect(
background_url,
base_url,
&rect,
style.background_size,
style.background_size_expression.as_deref(),
style.background_size_fit,
style.background_position,
style.font_size.unwrap_or(16.0),
root_font_size,
viewport,
image_cache,
) {
paint_image(
background_url,
base_url,
&image_rect,
&visible,
crate::ObjectFit::Fill,
pixmap,
image_cache,
None,
);
}
}
let border_color = style.border_color.or(style.color).unwrap_or([0, 0, 0, 255]);
let mut border_paint = Paint::default();
border_paint.set_color(Color::from_rgba8(
border_color[0],
border_color[1],
border_color[2],
border_color[3],
));
let mut borders = PathBuilder::new();
let mut push_edge = |edge: crate::Rect| {
let edge = match clip {
Some(clip) => edge.intersect(&clip),
None => Some(edge),
};
if let Some(edge) = edge {
if let Some(rect) = Rect::from_xywh(edge.x, edge.y, edge.width, edge.height) {
borders.push_rect(rect);
}
}
};
if style.border.top > 0.0 {
push_edge(crate::Rect {
x: rect.x,
y: rect.y,
width: rect.width,
height: style.border.top,
});
}
if style.border.right > 0.0 {
push_edge(crate::Rect {
x: rect.x + rect.width - style.border.right,
y: rect.y,
width: style.border.right,
height: rect.height,
});
}
if style.border.bottom > 0.0 {
push_edge(crate::Rect {
x: rect.x,
y: rect.y + rect.height - style.border.bottom,
width: rect.width,
height: style.border.bottom,
});
}
if style.border.left > 0.0 {
push_edge(crate::Rect {
x: rect.x,
y: rect.y,
width: style.border.left,
height: rect.height,
});
}
if let Some(path) = borders.finish() {
pixmap.fill_path(
&path,
&border_paint,
FillRule::Winding,
Transform::identity(),
None,
);
}
}
fn paint_positioned_pseudo(
text_engine: &mut crate::inline::TextEngine,
pixmap: &mut Pixmap,
style: &crate::LayoutStyle,
containing_block: &crate::Rect,
viewport: (f32, f32),
root_font_size: f32,
ancestor_clip: Option<crate::Rect>,
base_url: Option<&str>,
image_cache: &mut RenderResourceCache,
) {
if style.position != Some(taffy::Position::Absolute) {
return;
}
let em = style.font_size.unwrap_or(16.0);
let resolve = |dimension: crate::Dimension, basis: f32| {
match dimension.resolve(em, root_font_size, viewport.0 / 100.0, viewport.1 / 100.0) {
crate::Dimension::Px(value) => Some(value),
crate::Dimension::Percent(value) => Some(value * basis),
_ => None,
}
};
let top = style.inset[0].and_then(|value| resolve(value, containing_block.height));
let right = style.inset[1].and_then(|value| resolve(value, containing_block.width));
let bottom = style.inset[2].and_then(|value| resolve(value, containing_block.height));
let left = style.inset[3].and_then(|value| resolve(value, containing_block.width));
let width = resolve(style.width, containing_block.width).or_else(|| {
Some(containing_block.width - left? - right?)
});
let height = resolve(style.height, containing_block.height).or_else(|| {
Some(containing_block.height - top? - bottom?)
});
let (Some(width), Some(height)) = (width, height) else { return };
if width <= 0.0 || height <= 0.0 {
return;
}
let x = left
.map(|value| containing_block.x + value)
.or_else(|| right.map(|value| containing_block.x + containing_block.width - value - width))
.unwrap_or(containing_block.x);
let y = top
.map(|value| containing_block.y + value)
.or_else(|| bottom.map(|value| containing_block.y + containing_block.height - value - height))
.unwrap_or(containing_block.y);
let rect = crate::Rect { x, y, width, height };
let visible = match ancestor_clip {
Some(clip) => rect.intersect(&clip),
None => Some(rect),
};
let Some(visible) = visible else { return };
let path = if style.border_radius > 0.5 {
rounded_rect_path(visible.x, visible.y, visible.width, visible.height, style.border_radius)
} else {
Rect::from_xywh(visible.x, visible.y, visible.width, visible.height).and_then(|rect| {
let mut builder = PathBuilder::new();
builder.push_rect(rect);
builder.finish()
})
};
let Some(path) = path else { return };
if style.mask_image.is_none() {
if let Some(color) = style.background_color {
let mut paint = Paint::default();
paint.set_color(Color::from_rgba8(color[0], color[1], color[2], color[3]));
pixmap.fill_path(
&path,
&paint,
FillRule::Winding,
Transform::identity(),
None,
);
}
if let Some((center, stops)) = &style.background_radial_gradient {
paint_radial_gradient(pixmap, &path, &rect, *center, stops);
}
if let Some((angle, center, stops)) = &style.background_conic_gradient {
paint_conic_gradient(pixmap, &rect, *angle, *center, stops);
}
if let Some((angle, stops)) = &style.background_gradient {
paint_linear_gradient(pixmap, &path, &rect, *angle, stops);
}
}
if let Some(mask_url) = &style.mask_image {
let fill = style
.background_color
.or(style.color)
.unwrap_or([0, 0, 0, 255]);
paint_mask(
mask_url,
base_url,
&visible,
fill,
style.background_gradient.as_ref(),
style.background_conic_gradient.as_ref(),
style.mask_size,
style.mask_repeat,
pixmap,
image_cache,
);
} else if let Some(bg_url) = &style.background_image {
if let Some(image_rect) = background_image_rect(
bg_url,
base_url,
&rect,
style.background_size,
style.background_size_expression.as_deref(),
style.background_size_fit,
style.background_position,
em,
root_font_size,
viewport,
image_cache,
) {
paint_image(
bg_url,
base_url,
&image_rect,
&visible,
crate::ObjectFit::Fill,
pixmap,
image_cache,
None,
);
}
}
if let Some(content) = style.before_content.as_deref().filter(|content| !content.is_empty()) {
let Some(item) = text_engine.push_generated_text(content, style) else { return };
let (text_width, text_height) = text_engine.measure(item, None);
let x = match style.justify_content {
Some(taffy::JustifyContent::CENTER) => rect.x + (rect.width - text_width) / 2.0,
Some(taffy::JustifyContent::FLEX_END | taffy::JustifyContent::END) => {
rect.x + rect.width - style.padding.right - text_width
}
_ => rect.x + style.padding.left,
};
let y = match style.align_items {
Some(taffy::AlignItems::CENTER) => rect.y + (rect.height - text_height) / 2.0,
Some(taffy::AlignItems::FLEX_END | taffy::AlignItems::END) => {
rect.y + rect.height - style.padding.bottom - text_height
}
_ => rect.y + style.padding.top,
};
text_engine.finalize(item, (x, y), text_width, Some(visible));
text_engine.paint_item(item, pixmap, (0.0, 0.0));
}
}
/// Fetch every `<img>` once (seeding `cache` for the paint pass) and record its
/// intrinsic (width, height) so layout can size replaced elements that have no
/// explicit dimensions. Keyed by the `<img>`'s NodeId.
fn collect_image_intrinsics(
tree: &DomTree,
viewport: (f32, f32),
base_url: Option<&str>,
cache: &mut RenderResourceCache,
) -> (
HashMap<obscura_dom::tree::NodeId, (f32, f32)>,
HashMap<obscura_dom::tree::NodeId, SelectedImage>,
) {
let mut out = std::collections::HashMap::new();
let mut selected = HashMap::new();
for nid in tree.descendants(tree.document()) {
let Some(node) = tree.get_node(nid) else { continue };
if node.as_element().map(|e| e.local.as_ref() != "img").unwrap_or(true) {
continue;
}
let Some((url, density)) = resolve_img_url(tree, nid, viewport) else { continue };
let resolved_url = resolve_resource_url(&url, base_url).unwrap_or(url);
selected.insert(
nid,
SelectedImage {
resolved_url: resolved_url.clone(),
density,
},
);
let Some(bytes) = fetch_bytes(&resolved_url, None, cache) else { continue };
let dimensions = image_dimensions(&bytes).map(|(width, height)| (width as f32, height as f32))
.or_else(|| svg_intrinsic(&bytes));
if let Some((w, h)) = dimensions {
if w > 0.0 && h > 0.0 {
// A 2x (or w-descriptor) candidate's raw pixels are density
// times its CSS size; divide so layout sees CSS px, or every
// responsive image occupies twice its design size.
out.insert(nid, (w / density, h / density));
}
}
}
(out, selected)
}
/// Add intrinsic metadata for CSS `content:url(...)` images after the first
/// cascade has exposed their computed URL. Returns true when a new intrinsic
/// entry was added and layout therefore needs one resource-aware retry.
fn collect_content_image_intrinsics(
tree: &DomTree,
styles: &std::collections::HashMap<obscura_dom::tree::NodeId, crate::LayoutStyle>,
base_url: Option<&str>,
cache: &mut RenderResourceCache,
out: &mut std::collections::HashMap<obscura_dom::tree::NodeId, (f32, f32)>,
selected: &mut HashMap<obscura_dom::tree::NodeId, SelectedImage>,
) -> bool {
let mut changed = false;
for (&nid, style) in styles {
let Some(node) = tree.get_node(nid) else {
continue;
};
if node
.as_element()
.map_or(true, |name| name.local.as_ref() != "img")
{
continue;
}
let Some(url) = style.content_image.as_deref() else {
continue;
};
let resolved_url =
resolve_resource_url(url, base_url).unwrap_or_else(|| url.to_string());
selected.insert(
nid,
SelectedImage {
resolved_url: resolved_url.clone(),
density: 1.0,
},
);
let Some(bytes) = fetch_bytes(&resolved_url, None, cache) else {
continue;
};
let dimensions = image_dimensions(&bytes)
.map(|(width, height)| (width as f32, height as f32))
.or_else(|| svg_intrinsic(&bytes));
let Some((width, height)) = dimensions else {
continue;
};
if width <= 0.0 || height <= 0.0 {
continue;
}
changed |= out.insert(nid, (width, height)) != Some((width, height));
}
changed
}
/// Choose the URL to paint for an `<img>`. Browsers do not use `src` alone:
/// a wrapping `<picture>`'s `<source>`s, `srcset`, and `sizes` select by
/// type/media/viewport/density, and lazy-loaded images keep the real URL in
/// `data-src`/`data-srcset` with `src` holding a 1x1 placeholder until script
/// swaps it in. Since obscura may not have run the site's lazy-load script,
/// resolve the same URL the browser would end up with: a matching `<picture>`
/// source first, then a real candidate from `srcset`/`data-srcset`, then a
/// non-inline `src`/`data-*` URL, then any `src` (an inlined data: image).
fn resolve_img_url(
tree: &DomTree,
nid: obscura_dom::tree::NodeId,
viewport: (f32, f32),
) -> Option<(String, f32)> {
let node = tree.get_node(nid)?;
// A <picture>'s preceding, type/media-matching <source> wins over the
// <img>'s own attributes (HTML "update the source set").
if let Some(pick) = picture_source_url(tree, nid, viewport) {
return Some(pick);
}
let sizes = node.get_attribute("sizes");
for a in ["srcset", "data-srcset"] {
if let Some(v) = node.get_attribute(a) {
if let Some(pick) = best_srcset_candidate(v, sizes, viewport) {
return Some(pick);
}
}
}
let url_attrs = ["src", "data-src", "data-lazy-src", "data-original", "data-fallback-src", "data-lazy"];
// A non-inline URL first (a data: src is usually the lazy-load placeholder).
for a in url_attrs {
if let Some(v) = node.get_attribute(a) {
let v = v.trim();
if !v.is_empty() && !v.starts_with("data:") {
return Some((v.to_string(), 1.0));
}
}
}
// Otherwise fall back to whatever is there (an inlined data: image).
for a in url_attrs {
if let Some(v) = node.get_attribute(a) {
let v = v.trim();
if !v.is_empty() {
return Some((v.to_string(), 1.0));
}
}
}
None
}
/// When `img_nid` is an `<img>` inside a `<picture>`, walk its preceding
/// `<source>` siblings in document order and return the selected URL of the
/// first supported one (matching `type` and `media`), per WebKit's
/// `HTMLImageElement::bestFitSourceFromPictureElement`. `None` means no source
/// applied and the caller should fall back to the `<img>`'s own attributes.
fn picture_source_url(
tree: &DomTree,
img_nid: obscura_dom::tree::NodeId,
viewport: (f32, f32),
) -> Option<(String, f32)> {
let img = tree.get_node(img_nid)?;
let parent = img.parent?;
let is_picture = tree
.get_node(parent)
.and_then(|p| p.as_element().map(|e| e.local.as_ref() == "picture"))
.unwrap_or(false);
if !is_picture {
return None;
}
for cid in tree.children(parent) {
// Only sources that precede the <img> contribute.
if cid == img_nid {
break;
}
let Some(child) = tree.get_node(cid) else { continue };
if child.as_element().map(|e| e.local.as_ref() != "source").unwrap_or(true) {
continue;
}
let Some(srcset) = child.get_attribute("srcset") else { continue };
if srcset.trim().is_empty() {
continue;
}
if let Some(t) = child.get_attribute("type") {
if !source_type_supported(t) {
continue;
}
}
if let Some(m) = child.get_attribute("media") {
if !m.trim().is_empty()
&& !crate::css::media_query_applies_for_viewport(m, viewport)
{
continue;
}
}
let sizes = child.get_attribute("sizes");
if let Some(u) = best_srcset_candidate(srcset, sizes, viewport) {
return Some(u);
}
}
None
}
/// Whether a `<source type=...>` names an image format this build can decode.
/// AVIF/JPEG-XL are intentionally excluded: the `image` crate cannot decode
/// them here, so a decodable `<img>` fallback must win over such a source.
fn source_type_supported(t: &str) -> bool {
matches!(
t.trim().to_ascii_lowercase().as_str(),
"image/jpeg" | "image/jpg" | "image/png" | "image/gif" | "image/webp"
| "image/bmp" | "image/svg+xml" | "image/x-icon" | "image/vnd.microsoft.icon"
)
}
/// Pick one URL from a `srcset` list, matching the WebKit/Blink selection:
/// normalize each `w` descriptor to an effective density (`w / source-size`,
/// with the source-size taken from `sizes` or falling back to the viewport
/// width), treat `x` descriptors as-is and a bare candidate as `1x`, then pick
/// the smallest density at least the device pixel ratio (1 at DPR 1), else the
/// largest available.
/// Returns the picked candidate URL and its pixel density. The density is the
/// x-descriptor (or, for w-descriptors, width / source-size): the factor the
/// file's raw pixels must be divided by to get CSS px. Laying out with raw
/// pixels made every 2x responsive image occupy twice its design size.
fn best_srcset_candidate(
srcset: &str,
sizes: Option<&str>,
viewport: (f32, f32),
) -> Option<(String, f32)> {
const DPR: f32 = 1.0;
let source_size = source_size_px(sizes, viewport);
let mut cands: Vec<(f32, String)> = Vec::new();
// Parse candidates WHATWG-style: a URL is a run of non-whitespace (so a
// data: URI's internal commas stay part of it, unlike a naive split on
// ','), optionally followed by a descriptor up to the next comma.
let is_ws = |c: char| c.is_whitespace();
let mut rest = srcset.trim_start_matches(|c: char| is_ws(c) || c == ',');
while !rest.is_empty() {
let url_end = rest.find(is_ws).unwrap_or(rest.len());
let raw_url = &rest[..url_end];
rest = &rest[url_end..];
// Trailing commas on the URL mean the candidate had no descriptor.
let url = raw_url.trim_end_matches(',');
let no_desc = url.len() != raw_url.len();
rest = rest.trim_start_matches(is_ws);
let desc = if no_desc {
""
} else {
let d_end = rest.find(',').unwrap_or(rest.len());
let d = rest[..d_end].trim();
rest = &rest[d_end..];
d
};
rest = rest.trim_start_matches(|c: char| c == ',' || is_ws(c));
if url.is_empty() {
continue;
}
let density = if desc.is_empty() {
1.0
} else if let Some(w) = desc.strip_suffix('w').and_then(|s| s.parse::<f32>().ok()) {
if source_size > 0.0 { w / source_size } else { continue }
} else if let Some(x) = desc.strip_suffix('x').and_then(|s| s.parse::<f32>().ok()) {
x
} else {
// An `h` (height) descriptor or malformed token: skip the candidate.
continue;
};
cands.push((density, url.to_string()));
}
if cands.is_empty() {
return None;
}
cands.sort_by(|a, b| a.0.partial_cmp(&b.0).unwrap_or(std::cmp::Ordering::Equal));
let pick = cands
.iter()
.find(|(d, _)| *d >= DPR)
.map(|(d, u)| (u.clone(), *d))
.unwrap_or_else(|| {
let (d, u) = cands.last().unwrap();
(u.clone(), *d)
});
Some((pick.0, pick.1.max(0.01)))
}
/// Approximate the CSS px size an image will be displayed at, from its `sizes`
/// attribute: the first entry whose media condition holds at our assumed
/// desktop viewport (a bare entry always holds), else the viewport width. Used
/// only to convert `w` descriptors to densities, so a coarse value is fine.
fn source_size_px(sizes: Option<&str>, viewport: (f32, f32)) -> f32 {
let Some(sizes) = sizes else { return viewport.0 };
for entry in sizes.split(',') {
let entry = entry.trim();
if entry.is_empty() {
continue;
}
let (cond, len) = split_size_entry(entry);
if let Some(cond) = cond {
if !crate::css::media_query_applies_for_viewport(&cond, viewport) {
continue;
}
}
if let Some(px) = length_to_px(&len, viewport.0) {
return px;
}
}
viewport.0
}
/// Split one `sizes` entry into its optional leading media condition and its
/// trailing `<length>`. Tokenizes on whitespace at paren depth 0 so a
/// `calc(...)` length or a parenthesized condition stays intact; the last
/// token is the length, anything before it is the condition.
fn split_size_entry(entry: &str) -> (Option<String>, String) {
let mut tokens: Vec<String> = Vec::new();
let mut cur = String::new();
let mut depth = 0i32;
for c in entry.chars() {
match c {
'(' => { depth += 1; cur.push(c); }
')' => { depth -= 1; cur.push(c); }
c if c.is_whitespace() && depth == 0 => {
if !cur.is_empty() { tokens.push(std::mem::take(&mut cur)); }
}
c => cur.push(c),
}
}
if !cur.is_empty() {
tokens.push(cur);
}
let len = tokens.pop().unwrap_or_default();
let cond = if tokens.is_empty() { None } else { Some(tokens.join(" ")) };
(cond, len)
}
/// Resolve a `sizes` length to px against the assumed viewport. `vw`/`%` scale
/// by the viewport width; `px` is literal; `em`/`rem` use the 16px root.
/// `calc()` and other forms return `None` (the caller tries the next entry).
fn length_to_px(len: &str, viewport_width: f32) -> Option<f32> {
let t = len.trim().to_ascii_lowercase();
let num = |s: &str| s.trim().parse::<f32>().ok();
if let Some(v) = t.strip_suffix("vw").and_then(num) { return Some(v / 100.0 * viewport_width); }
if let Some(v) = t.strip_suffix('%').and_then(num) { return Some(v / 100.0 * viewport_width); }
if let Some(v) = t.strip_suffix("px").and_then(num) { return Some(v); }
if let Some(v) = t.strip_suffix("rem").and_then(num) { return Some(v * 16.0); }
if let Some(v) = t.strip_suffix("em").and_then(num) { return Some(v * 16.0); }
num(&t)
}
fn paint_image(
src: &str,
base_url: Option<&str>,
rect: &crate::Rect,
visible_rect: &crate::Rect,
object_fit: crate::ObjectFit,
pixmap: &mut Pixmap,
cache: &mut RenderResourceCache,
transform: Option<ImageAffine>,
) -> bool {
if rect.width <= 0.0 || rect.height <= 0.0 {
return false;
}
let Some(bytes) = fetch_bytes(src, base_url, cache) else { return false };
let svg = is_svg(&bytes);
// Destination sub-rect within the element box. `Fill` keeps the historical
// behavior (stretch the image to the whole box); the other modes need the
// image's intrinsic size to preserve its aspect ratio, and fall back to
// fill when it cannot be read.
let dest = if object_fit == crate::ObjectFit::Fill {
*rect
} else {
let intrinsic = if svg {
svg_intrinsic(&bytes)
} else {
image_dimensions(&bytes).map(|(w, h)| (w as f32, h as f32))
};
match intrinsic {
Some((iw, ih)) => object_fit_dest(rect, iw, ih, object_fit),
None => *rect,
}
};
let (dw, dh) = (dest.width.round().max(1.0) as u32, dest.height.round().max(1.0) as u32);
let content = if svg {
render_svg(&bytes, dw, dh)
} else {
raster_to_pixmap(&bytes, dw, dh)
};
let Some(content) = content else { return false };
// The raster may not paint past `visible_rect` (the border box already
// intersected with the ancestor overflow clip): `Cover`/`None` can size
// the image past the box, and an ancestor clip can cut into the box
// itself. Only the fully-inside case takes the unmasked fast path.
let clip = if dest.width > visible_rect.width + 0.5
|| dest.height > visible_rect.height + 0.5
|| dest.x < visible_rect.x - 0.5
|| dest.y < visible_rect.y - 0.5
{
box_clip_mask(pixmap.width(), pixmap.height(), visible_rect)
} else {
None
};
pixmap.draw_pixmap(
dest.x as i32,
dest.y as i32,
content.as_ref(),
&tiny_skia::PixmapPaint::default(),
transform
.map(ImageAffine::tiny_skia)
.unwrap_or_else(Transform::identity),
clip.as_ref(),
);
true
}
/// The destination sub-rect for a replaced element's image within its box,
/// given the image's intrinsic `(iw, ih)` size and `object-fit`. Centered in
/// the box; for `Cover`/`None` it can extend past the box edges (the caller
/// clips it). Aspect ratio is preserved for every mode except `Fill`.
fn object_fit_dest(box_rect: &crate::Rect, iw: f32, ih: f32, fit: crate::ObjectFit) -> crate::Rect {
let (bw, bh) = (box_rect.width, box_rect.height);
if iw <= 0.0 || ih <= 0.0 {
return *box_rect;
}
let (dw, dh) = match fit {
crate::ObjectFit::Fill => (bw, bh),
crate::ObjectFit::Contain => {
let s = (bw / iw).min(bh / ih);
(iw * s, ih * s)
}
crate::ObjectFit::Cover => {
let s = (bw / iw).max(bh / ih);
(iw * s, ih * s)
}
crate::ObjectFit::None => (iw, ih),
crate::ObjectFit::ScaleDown => {
// min(Contain-size, intrinsic-size): the Contain fit, but never
// scaled up past the image's own pixels.
let s = (bw / iw).min(bh / ih).min(1.0);
(iw * s, ih * s)
}
};
crate::Rect {
x: box_rect.x + (bw - dw) / 2.0,
y: box_rect.y + (bh - dh) / 2.0,
width: dw,
height: dh,
}
}
/// The intrinsic `(width, height)` of an SVG image from its size/`viewBox`,
/// used to preserve aspect ratio under `object-fit`. Parses the SVG once; the
/// eventual raster re-parses in `render_svg` (only reached for a non-`fill`
/// object-fit on an SVG image, which is rare).
fn svg_intrinsic(bytes: &[u8]) -> Option<(f32, f32)> {
let tree = usvg::Tree::from_data(bytes, &usvg::Options::default()).ok()?;
let size = tree.size();
if size.width() > 0.0 && size.height() > 0.0 {
Some((size.width(), size.height()))
} else {
None
}
}
/// A full-pixmap clip mask admitting only the pixels inside `rect`, used to
/// crop an `object-fit: cover|none` image to its element box.
fn box_clip_mask(pw: u32, ph: u32, rect: &crate::Rect) -> Option<tiny_skia::Mask> {
let mut mask = tiny_skia::Mask::new(pw, ph)?;
let r = Rect::from_xywh(rect.x, rect.y, rect.width, rect.height)?;
let mut pb = PathBuilder::new();
pb.push_rect(r);
let path = pb.finish()?;
mask.fill_path(&path, FillRule::Winding, true, Transform::identity());
Some(mask)
}
/// Sniff SVG content: either an XML/SVG prolog, or a bare `<svg` root tag
/// (both are valid, and image responses commonly omit the XML declaration).
fn is_svg(bytes: &[u8]) -> bool {
let head = &bytes[..bytes.len().min(256)];
let text = String::from_utf8_lossy(head);
let trimmed = text.trim_start_matches('\u{feff}').trim_start();
trimmed.starts_with("<?xml") || trimmed.starts_with("<svg")
}
/// Rasterize SVG bytes to a `width` x `height` pixmap, scaled to fit (matching
/// how a replaced element like `<img>` sizes its intrinsic content).
fn render_svg(bytes: &[u8], width: u32, height: u32) -> Option<Pixmap> {
let fonts = svg_font_database();
render_svg_with_font_database(bytes, width, height, &fonts)
}
fn render_svg_with_font_database(
bytes: &[u8],
width: u32,
height: u32,
fonts: &std::sync::Arc<usvg::fontdb::Database>,
) -> Option<Pixmap> {
if width == 0 || height == 0 {
return None;
}
let mut opts = usvg::Options::default();
// The outer replaced element supplies the SVG document viewport. Force
// that used CSS size onto the root before usvg resolves `viewBox`:
// a missing height is represented as 100%, which usvg otherwise resolves
// against the viewBox height itself. `<svg width=32 viewBox="0 0 223
// 236">` would therefore become a 32x236 viewport; its artwork is fitted
// into a thin centered strip and then the whole strip is scaled to 32x34.
// Author `preserveAspectRatio` still controls fitting inside this viewport.
// usvg resolves root dimensions before an injected stylesheet can
// override them, so provide the used viewport as actual root attributes.
let viewport_svg = svg_with_root_viewport(bytes, width, height)?;
opts.default_size = usvg::Size::from_wh(width as f32, height as f32)?;
opts.font_family = "Liberation Serif".to_string();
opts.fontdb = std::sync::Arc::clone(fonts);
let tree = usvg::Tree::from_data(&viewport_svg, &opts).ok()?;
let size = tree.size();
if size.width() <= 0.0 || size.height() <= 0.0 {
return None;
}
let mut svg_pixmap = Pixmap::new(width, height)?;
let transform = Transform::from_scale(width as f32 / size.width(), height as f32 / size.height());
resvg::render(&tree, transform, &mut svg_pixmap.as_mut());
Some(svg_pixmap)
}
/// A deterministic font database shared by every SVG raster in the process.
/// Constructing/scanning a database per icon is far too expensive for pages
/// with SVG-heavy navigation and would be prohibitive for future repeated
/// frame capture. The embedded faces are the same stable browser-generic
/// families used by the HTML text engine.
fn svg_font_database() -> std::sync::Arc<usvg::fontdb::Database> {
static DATABASE: std::sync::OnceLock<std::sync::Arc<usvg::fontdb::Database>> =
std::sync::OnceLock::new();
std::sync::Arc::clone(DATABASE.get_or_init(|| {
let mut database = usvg::fontdb::Database::new();
for bytes in [
FONT_BYTES,
FONT_BOLD_BYTES,
FONT_OBLIQUE_BYTES,
FONT_BOLD_OBLIQUE_BYTES,
SERIF_FONT_BYTES,
MONO_FONT_BYTES,
] {
database.load_font_data(bytes.to_vec());
}
database.set_sans_serif_family("Liberation Sans");
database.set_serif_family("Liberation Serif");
database.set_monospace_family("Liberation Mono");
std::sync::Arc::new(database)
}))
}
fn svg_font_database_with_web_fonts(
web_fonts: &[crate::inline::WebFont],
) -> std::sync::Arc<usvg::fontdb::Database> {
let base = svg_font_database();
if web_fonts.is_empty() {
return base;
}
// `fontdb::Database::clone` shares each binary source; only the page's
// already-decoded user fonts allocate here, once per page rather than once
// per SVG. HTML shaping needs the same bytes, so retaining both databases
// is the cost of keeping the rasterizer and layout engine deterministic.
let mut database = (*base).clone();
for font in web_fonts {
database.load_font_data(font.data.clone());
}
std::sync::Arc::new(database)
}
fn has_inline_svg_text(tree: &DomTree) -> bool {
tree.descendants(tree.document()).into_iter().any(|nid| {
tree.get_node(nid).is_some_and(|node| {
node.as_element()
.is_some_and(|name| matches!(name.local.as_ref(), "text" | "tspan" | "textPath"))
})
})
}
/// Return SVG XML whose root `width`/`height` are the resolved CSS viewport.
///
/// This is deliberately a narrow XML start-tag rewrite rather than a DOM
/// reserialization: all namespaces, styles, definitions, and source order
/// remain byte-for-byte intact. Existing attribute values are replaced;
/// missing ones are appended. Quoted `>` characters are respected while
/// finding the end of the root tag.
fn svg_with_root_viewport(bytes: &[u8], width: u32, height: u32) -> Option<Vec<u8>> {
let source = std::str::from_utf8(bytes).ok()?;
let start = source.find("<svg")?;
let tail = &source[start..];
let mut quote = None;
let mut tag_end = None;
for (offset, ch) in tail.char_indices() {
match (quote, ch) {
(Some(open), close) if close == open => quote = None,
(None, '"' | '\'') => quote = Some(ch),
(None, '>') => {
tag_end = Some(start + offset);
break;
}
_ => {}
}
}
let tag_end = tag_end?;
let mut root = source[start..=tag_end].to_string();
for (name, value) in [("width", width), ("height", height)] {
if let Some((value_start, value_end)) = svg_root_attr_value_range(&root, name) {
root.replace_range(value_start..value_end, &value.to_string());
} else {
root.insert_str(root.len() - 1, &format!(" {name}=\"{value}\""));
}
}
let mut output = String::with_capacity(source.len() + 32);
output.push_str(&source[..start]);
output.push_str(&root);
output.push_str(&source[tag_end + 1..]);
Some(output.into_bytes())
}
/// Value byte range for one attribute in an `<svg ...>` start tag.
fn svg_root_attr_value_range(tag: &str, wanted: &str) -> Option<(usize, usize)> {
let bytes = tag.as_bytes();
let mut index = "<svg".len();
while index < bytes.len() {
while index < bytes.len() && bytes[index].is_ascii_whitespace() {
index += 1;
}
if index >= bytes.len() || bytes[index] == b'>' || bytes[index] == b'/' {
return None;
}
let name_start = index;
while index < bytes.len()
&& !bytes[index].is_ascii_whitespace()
&& bytes[index] != b'='
&& bytes[index] != b'>'
&& bytes[index] != b'/'
{
index += 1;
}
let name_end = index;
while index < bytes.len() && bytes[index].is_ascii_whitespace() {
index += 1;
}
if index >= bytes.len() || bytes[index] != b'=' {
continue;
}
index += 1;
while index < bytes.len() && bytes[index].is_ascii_whitespace() {
index += 1;
}
let (value_start, value_end) = if index < bytes.len()
&& matches!(bytes[index], b'"' | b'\'')
{
let delimiter = bytes[index];
index += 1;
let start = index;
while index < bytes.len() && bytes[index] != delimiter {
index += 1;
}
let end = index;
index = (index + 1).min(bytes.len());
(start, end)
} else {
let start = index;
while index < bytes.len()
&& !bytes[index].is_ascii_whitespace()
&& bytes[index] != b'>'
&& bytes[index] != b'/'
{
index += 1;
}
(start, index)
};
if &tag[name_start..name_end] == wanted {
return Some((value_start, value_end));
}
}
None
}
/// Serialize an inline `<svg>` subtree (rooted at `root`) back to a standalone
/// SVG document string. Emits `<tag attr="v">children</tag>` for the element
/// and every descendant, preserving the root's `viewBox`/`width`/`height` and
/// all `<defs>`/`<symbol>`/`<use>`/`<path>` structure so resvg can rasterize it
/// as a self-contained document. SVG is XML-clean, so there are no HTML
/// void-element or optional-close rules to apply; every element gets an
/// explicit closing tag. The root gains an `xmlns` declaration when it lacks
/// one (common for inline svg, whose namespace is implied by the HTML parser
/// but required for usvg to parse the string on its own).
#[cfg(test)]
fn serialize_svg(tree: &DomTree, root: obscura_dom::tree::NodeId) -> String {
let mut buf = String::new();
serialize_svg_node(tree, root, true, None, &mut buf);
buf
}
/// Serialize an inline SVG while carrying the page's computed author styling
/// into the standalone document consumed by resvg. External page stylesheets
/// are otherwise outside that document, so class-driven SVG text and icons
/// silently fall back to presentation attributes or SVG defaults.
fn serialize_svg_styled(
tree: &DomTree,
root: obscura_dom::tree::NodeId,
styles: &std::collections::HashMap<obscura_dom::tree::NodeId, crate::LayoutStyle>,
) -> String {
let mut buf = String::new();
serialize_svg_node(tree, root, true, Some(styles), &mut buf);
buf
}
fn inject_svg_current_color(markup: &mut String, color: [u8; 4]) {
let Some(start) = markup.find("<svg") else { return };
let Some(end) = markup[start..].find('>').map(|offset| start + offset) else { return };
let root = &markup[start..end];
// An explicit presentation attribute already survives serialization and
// is the correct local currentColor source.
if root.contains(" color=") {
return;
}
let attribute = format!(
" color=\"#{:02x}{:02x}{:02x}\"",
color[0], color[1], color[2]
);
markup.insert_str(start + "<svg".len(), &attribute);
}
fn serialize_svg_node(
tree: &DomTree,
nid: obscura_dom::tree::NodeId,
is_root: bool,
styles: Option<&std::collections::HashMap<obscura_dom::tree::NodeId, crate::LayoutStyle>>,
buf: &mut String,
) {
let node = match tree.get_node(nid) {
Some(n) => n,
None => return,
};
if let Some(text) = node.text_content_of_text_node() {
svg_escape_text(text, buf);
return;
}
let name = match node.as_element() {
Some(n) => n,
// Document/comment/PI: no tag of its own, emit only element children.
None => {
for child in tree.children(nid) {
serialize_svg_node(tree, child, false, styles, buf);
}
return;
}
};
let tag = name.local.as_ref();
buf.push('<');
buf.push_str(tag);
let mut has_xmlns = false;
let mut source_style: Option<String> = None;
if let Some(attrs) = node.attrs() {
for attr in attrs {
// Emit the local name only, dropping any prefix (`xlink:href` ->
// `href`): resvg reads both, and a bare local avoids needing an
// `xmlns:xlink` declaration in the standalone document.
let aname = attr.name.local.as_ref();
// HTML frameworks commonly stamp hydration attributes such as
// `q:id` onto inline SVG. In an HTML document that name is fine,
// but our standalone XML serialization has no matching `xmlns:q`,
// so one irrelevant attribute makes usvg reject the entire logo.
// Namespace-aware attributes arrive with a clean local name;
// discard only literal, unbound colon names from the HTML parser.
if aname.contains(':') {
continue;
}
if aname == "xmlns" {
has_xmlns = true;
}
if styles.is_some() && aname == "style" {
source_style = Some(attr.value.to_string());
continue;
}
buf.push(' ');
buf.push_str(aname);
buf.push_str("=\"");
svg_escape_attr(&attr.value, buf);
buf.push('"');
}
}
if styles.is_some() {
let mut declarations = String::new();
if let Some(source) = source_style.as_deref() {
declarations.push_str(source.trim());
if !declarations.is_empty() && !declarations.ends_with(';') {
declarations.push(';');
}
}
let mut append = |name: &str, value: &str| {
if value.trim().is_empty() {
return;
}
declarations.push_str(name);
declarations.push(':');
declarations.push_str(value);
declarations.push_str("!important;");
};
if let Some(computed) = styles.and_then(|all| all.get(&nid)) {
if let Some(value) = computed.svg_fill.as_deref() {
append(
"fill",
if value.eq_ignore_ascii_case("currentcolor") {
"currentColor"
} else {
value
},
);
}
if let Some(value) = computed.svg_stroke.as_deref() {
append(
"stroke",
if value.eq_ignore_ascii_case("currentcolor") {
"currentColor"
} else {
value
},
);
}
if let Some(value) = computed.svg_stroke_width.as_deref() {
append("stroke-width", value);
}
if matches!(tag, "svg" | "text" | "textPath" | "textpath" | "tspan") {
if let Some(value) = computed.font_size {
append("font-size", &format!("{value}px"));
}
if let Some(value) = computed.font_weight.as_deref() {
append("font-weight", value);
}
if let Some(value) = computed.font_family.as_deref() {
append("font-family", value);
}
if computed.font_style_italic == Some(true) {
append("font-style", "italic");
}
}
if let Some(color) = computed.color {
append(
"color",
&format!("#{:02x}{:02x}{:02x}", color[0], color[1], color[2]),
);
}
if let Some(opacity) = computed.opacity {
append("opacity", &opacity.to_string());
}
}
if !declarations.is_empty() {
buf.push_str(" style=\"");
svg_escape_attr(&declarations, buf);
buf.push('"');
}
}
if is_root && !has_xmlns {
buf.push_str(" xmlns=\"http://www.w3.org/2000/svg\"");
}
buf.push('>');
for child in tree.children(nid) {
serialize_svg_node(tree, child, false, styles, buf);
}
buf.push_str("</");
buf.push_str(tag);
buf.push('>');
}
fn svg_escape_text(s: &str, buf: &mut String) {
for c in s.chars() {
match c {
'&' => buf.push_str("&amp;"),
'<' => buf.push_str("&lt;"),
'>' => buf.push_str("&gt;"),
_ => buf.push(c),
}
}
}
fn svg_escape_attr(s: &str, buf: &mut String) {
for c in s.chars() {
match c {
'&' => buf.push_str("&amp;"),
'<' => buf.push_str("&lt;"),
'"' => buf.push_str("&quot;"),
_ => buf.push(c),
}
}
}
/// Resolve `<use>` elements in an inline `<svg>` subtree against either a
/// document-level symbol sprite (`href="#id"`) or an external sprite file
/// (`href="url#id"`), splicing the referenced symbol into the standalone SVG
/// handed to resvg. Symbols already inside `root` need no injection.
fn inject_external_sprites(
tree: &DomTree,
root: obscura_dom::tree::NodeId,
base_url: Option<&str>,
markup: &mut String,
cache: &mut RenderResourceCache,
sprite_cache: &mut std::collections::HashMap<String, Option<String>>,
) {
// Distinct external references (full href, url, fragment id), in first-seen
// order. Dedupe so one symbol referenced by several `<use>` is fetched and
// injected once (the rewrite below still fixes every occurrence).
let root_descendants = tree.descendants(root);
let mut refs: Vec<(String, String, String)> = Vec::new();
let mut local_fragments = Vec::new();
for nid in tree.descendants(root) {
let Some(node) = tree.get_node(nid) else { continue };
let Some(el) = node.as_element() else { continue };
if el.local.as_ref() != "use" {
continue;
}
// `get_attribute` matches by local name, so a single "href" lookup
// already covers both `href` and `xlink:href`; check the prefixed form
// too for completeness.
let Some(href) = node
.get_attribute("href")
.or_else(|| node.get_attribute("xlink:href"))
else {
continue;
};
let Some(hash) = href.find('#') else { continue };
let (url, frag) = (&href[..hash], &href[hash + 1..]);
if frag.is_empty() {
continue;
}
if url.is_empty() {
if !local_fragments.iter().any(|existing| existing == frag) {
local_fragments.push(frag.to_string());
}
continue;
}
let entry = (href.to_string(), url.to_string(), frag.to_string());
if !refs.contains(&entry) {
refs.push(entry);
}
}
let mut defs = String::new();
let mut rewrites: Vec<(String, String)> = Vec::new();
let wanted_local: std::collections::HashSet<&str> =
local_fragments.iter().map(String::as_str).collect();
let mut local_nodes = std::collections::HashMap::new();
if !wanted_local.is_empty() {
for nid in tree.descendants(tree.document()) {
let Some(node) = tree.get_node(nid) else { continue };
let Some(id) = node.get_attribute("id") else { continue };
if wanted_local.contains(id) {
local_nodes.entry(id.to_string()).or_insert(nid);
}
}
}
for frag in local_fragments {
let Some(&symbol_id) = local_nodes.get(&frag) else { continue };
if symbol_id == root || root_descendants.contains(&symbol_id) {
continue;
}
serialize_svg_node(tree, symbol_id, false, None, &mut defs);
}
for (href, url, frag) in &refs {
let key = format!("{url}#{frag}");
let symbol = sprite_cache
.entry(key)
.or_insert_with(|| {
let bytes = fetch_bytes(url, base_url, cache)?;
let text = String::from_utf8_lossy(&bytes);
// Drop `xlink:` prefixes in the fetched fragment (resvg reads a
// bare `href`), matching how the local subtree is serialized and
// avoiding an undeclared-namespace parse error in the standalone
// document.
extract_svg_element_by_id(&text, frag).map(|s| s.replace("xlink:href", "href"))
})
.clone();
let Some(symbol) = symbol else { continue };
defs.push_str(&symbol);
rewrites.push((href.clone(), format!("#{frag}")));
}
if defs.is_empty() {
return;
}
// Splice the fetched symbols into a `<defs>` immediately after the opening
// `<svg ...>` tag (the first `>` in the serialized document).
if let Some(gt) = markup.find('>') {
markup.insert_str(gt + 1, &format!("<defs>{defs}</defs>"));
}
// Point each external `<use>` at the injected local symbol. The serialized
// href is attribute-escaped, so match against the escaped form.
for (href, local) in rewrites {
let from = format!("href=\"{}\"", svg_escape_attr_str(&href));
let to = format!("href=\"{}\"", svg_escape_attr_str(&local));
*markup = markup.replace(&from, &to);
}
}
/// Escape a string for use as an SVG attribute value (`&`, `<`, `"`), returning
/// it as an owned `String` (the buffer-writing `svg_escape_attr` in one call).
fn svg_escape_attr_str(s: &str) -> String {
let mut buf = String::new();
svg_escape_attr(s, &mut buf);
buf
}
/// Pull the element carrying `id="id"` (a `<symbol>`, `<g>`, `<path>`, ...) out
/// of an external sprite document, returned as a verbatim serialized substring
/// (its start tag through the matching end tag, or the self-closing tag alone).
/// A lightweight namespace-agnostic XML scan, not a full parse: usvg would
/// flatten `<symbol>`/`<use>` structure, and we want to re-inject the element
/// unchanged. Returns None when no element has that id.
fn extract_svg_element_by_id(sprite: &str, id: &str) -> Option<String> {
let mut i = 0usize;
while i < sprite.len() {
let rest = &sprite[i..];
if !rest.starts_with('<') {
// Advance to the next tag (skips text/whitespace between elements).
i += rest.find('<')?;
continue;
}
if rest.starts_with("<!--") {
i += rest.find("-->").map(|p| p + 3)?;
continue;
}
if rest.starts_with("<![CDATA[") {
i += rest.find("]]>").map(|p| p + 3)?;
continue;
}
if rest.starts_with("<!") || rest.starts_with("<?") || rest.starts_with("</") {
i += rest.find('>').map(|p| p + 1)?;
continue;
}
// A start tag: inner spans between '<' and '>'.
let gt = i + rest.find('>')?;
let inner = &sprite[i + 1..gt];
if tag_attr(inner, "id") == Some(id) {
if inner.trim_end().ends_with('/') {
return Some(sprite[i..=gt].to_string());
}
let name = tag_name(inner);
let end = element_end(sprite, gt + 1, name)?;
return Some(sprite[i..end].to_string());
}
i = gt + 1;
}
None
}
/// The tag name from a tag's inner text (the bytes between `<` and `>`),
/// dropping any leading `/` of an end tag and stopping at the first whitespace
/// or self-close slash.
fn tag_name(inner: &str) -> &str {
let inner = inner.trim_start().trim_start_matches('/');
let end = inner
.find(|c: char| c.is_ascii_whitespace() || c == '/')
.unwrap_or(inner.len());
&inner[..end]
}
/// The value of attribute `want` in a tag's inner text, or None if absent.
/// Matches attribute names whole (so `id` does not match `data-id`/`xml:id`)
/// and handles single/double quoted and bare values.
fn tag_attr<'a>(inner: &'a str, want: &str) -> Option<&'a str> {
let b = inner.as_bytes();
let mut i = 0usize;
// Skip the tag name.
while i < b.len() && !b[i].is_ascii_whitespace() {
i += 1;
}
while i < b.len() {
while i < b.len() && b[i].is_ascii_whitespace() {
i += 1;
}
if i >= b.len() || b[i] == b'/' {
break;
}
let name_start = i;
while i < b.len() && b[i] != b'=' && !b[i].is_ascii_whitespace() && b[i] != b'/' {
i += 1;
}
let name = &inner[name_start..i];
while i < b.len() && b[i].is_ascii_whitespace() {
i += 1;
}
if i < b.len() && b[i] == b'=' {
i += 1;
while i < b.len() && b[i].is_ascii_whitespace() {
i += 1;
}
let value = if i < b.len() && (b[i] == b'"' || b[i] == b'\'') {
let quote = b[i];
i += 1;
let vstart = i;
while i < b.len() && b[i] != quote {
i += 1;
}
let v = &inner[vstart..i.min(b.len())];
if i < b.len() {
i += 1;
}
v
} else {
let vstart = i;
while i < b.len() && !b[i].is_ascii_whitespace() && b[i] != b'/' {
i += 1;
}
&inner[vstart..i]
};
if name == want {
return Some(value);
}
} else if name == want {
// Valueless (boolean) attribute.
return Some("");
}
}
None
}
/// The byte offset just past the `</name>` that closes an element whose content
/// starts at `start`, tracking nesting of same-named tags (e.g. `<g>` inside
/// `<g>`). None if the document ends without a matching close.
fn element_end(sprite: &str, start: usize, name: &str) -> Option<usize> {
let mut i = start;
let mut depth = 1usize;
while i < sprite.len() {
let rest = &sprite[i..];
if !rest.starts_with('<') {
i += rest.find('<')?;
continue;
}
if rest.starts_with("<!--") {
i += rest.find("-->").map(|p| p + 3)?;
continue;
}
if rest.starts_with("<![CDATA[") {
i += rest.find("]]>").map(|p| p + 3)?;
continue;
}
if rest.starts_with("<!") || rest.starts_with("<?") {
i += rest.find('>').map(|p| p + 1)?;
continue;
}
let gt = i + rest.find('>')?;
let inner = &sprite[i + 1..gt];
if rest.starts_with("</") {
if tag_name(inner) == name {
depth -= 1;
if depth == 0 {
return Some(gt + 1);
}
}
} else if tag_name(inner) == name && !inner.trim_end().ends_with('/') {
depth += 1;
}
i = gt + 1;
}
None
}
/// A full-pixmap alpha mask that is opaque only inside `rect`, used to clip a
/// blit (e.g. an inline svg raster) to an ancestor's overflow-hidden region.
fn rect_clip_mask(width: u32, height: u32, rect: &crate::Rect) -> Option<tiny_skia::Mask> {
let mut mask = tiny_skia::Mask::new(width, height)?;
let r = Rect::from_xywh(rect.x, rect.y, rect.width, rect.height)?;
let mut pb = PathBuilder::new();
pb.push_rect(r);
let path = pb.finish()?;
mask.fill_path(&path, FillRule::Winding, true, Transform::identity());
Some(mask)
}
/// Paint a `mask-image`: the ubiquitous "colored, scalable icon" pattern,
/// where an SVG shape is used purely as a stencil and tinted by
/// `background-color`/`color` rather than carrying its own colors. Fetches
/// and rasterizes the mask the same way as an ordinary image, then repaints
/// every pixel it covers as `fill`, weighted by the mask's own alpha there
/// (its "coverage"), instead of drawing the mask's own pixel colors.
fn paint_mask(
src: &str,
base_url: Option<&str>,
rect: &crate::Rect,
fill: [u8; 4],
linear_gradient: Option<&(f32, Vec<([u8; 4], Option<f32>)>)>,
conic_gradient: Option<&(f32, (f32, f32), Vec<([u8; 4], Option<f32>)>)>,
mask_size: Option<(f32, f32)>,
mask_repeat: Option<(bool, bool)>,
pixmap: &mut Pixmap,
cache: &mut RenderResourceCache,
) -> bool {
if rect.width <= 0.0 || rect.height <= 0.0 {
return false;
}
let Some(bytes) = fetch_bytes(src, base_url, cache) else { return false };
let (box_width, box_height) = (rect.width.ceil() as u32, rect.height.ceil() as u32);
let (tile_width, tile_height) = mask_size
.map(|(width, height)| {
(
width.max(1.0).ceil() as u32,
height.max(1.0).ceil() as u32,
)
})
.unwrap_or((box_width, box_height));
let mask = if is_svg(&bytes) {
render_svg(&bytes, tile_width, tile_height)
} else {
raster_to_pixmap(&bytes, tile_width, tile_height)
};
let Some(mask) = mask else { return false };
let repeat = if mask_size.is_some() {
mask_repeat.unwrap_or((true, true))
} else {
mask_repeat.unwrap_or((false, false))
};
let normalized_linear =
linear_gradient.map(|(_, stops)| normalized_stops(stops));
let normalized_conic =
conic_gradient.map(|(_, _, stops)| normalized_stops(stops));
let Some(mut recolored) = Pixmap::new(box_width, box_height) else {
return false;
};
for y in 0..box_height {
if !repeat.1 && y >= tile_height {
continue;
}
let tile_y = if repeat.1 { y % tile_height } else { y };
for x in 0..box_width {
if !repeat.0 && x >= tile_width {
continue;
}
let tile_x = if repeat.0 { x % tile_width } else { x };
let coverage =
mask.pixels()[(tile_y * tile_width + tile_x) as usize].alpha() as u32;
if coverage == 0 {
continue;
}
let sample_x = rect.x + x as f32 + 0.5;
let sample_y = rect.y + y as f32 + 0.5;
let mut color = if let (Some((angle, center, _)), Some(stops)) =
(conic_gradient, normalized_conic.as_deref())
{
conic_color_at(rect, *angle, *center, stops, sample_x, sample_y)
} else if let (Some((angle, _)), Some(stops)) =
(linear_gradient, normalized_linear.as_deref())
{
linear_color_at(rect, *angle, stops, sample_x, sample_y)
} else {
fill
};
color[3] = ((color[3] as u32 * coverage) / 255) as u8;
recolored.pixels_mut()[(y * box_width + x) as usize] =
premultiplied(color);
}
}
pixmap.draw_pixmap(
rect.x.floor() as i32,
rect.y.floor() as i32,
recolored.as_ref(),
&tiny_skia::PixmapPaint::default(),
Transform::identity(),
None,
);
true
}
#[cfg(test)]
mod tests {
use super::*;
use obscura_dom::tree_sink::parse_html;
#[test]
fn scrolled_viewport_moves_document_content_but_not_fixed_subtrees() {
let tree = parse_html(
r#"<html style="margin:0"><body style="margin:0">
<div style="height:80px;background:#ff0000"></div>
<div style="height:80px;background:#0000ff"></div>
<div style="position:fixed;z-index:10;left:0;top:0;width:20px;height:20px;background:#00ff00">
<span style="color:#00ff00">x</span>
</div>
</body></html>"#,
);
let top = paint_dom_scrolled(&tree, (100.0, 80.0), None, (0.0, 0.0))
.expect("top viewport");
let scrolled = paint_dom_scrolled(&tree, (100.0, 80.0), None, (0.0, 80.0))
.expect("scrolled viewport");
let top_content = top.pixel(50, 10).expect("top content");
assert!(
top_content.red() > 240 && top_content.blue() < 15,
"top viewport should show first red block: {top_content:?}"
);
let scrolled_content = scrolled.pixel(50, 10).expect("scrolled content");
assert!(
scrolled_content.blue() > 240 && scrolled_content.red() < 15,
"scrolled viewport should show second blue block: {scrolled_content:?}"
);
for (name, pixmap) in [("top", &top), ("scrolled", &scrolled)] {
let fixed = pixmap.pixel(5, 5).expect("fixed content");
assert!(
fixed.green() > 240 && fixed.red() < 15 && fixed.blue() < 15,
"{name} viewport should keep fixed subtree at the viewport origin: {fixed:?}"
);
}
}
#[test]
fn repeated_scroll_captures_reuse_immutable_layout_geometry() {
let tree = parse_html(
r#"<html style="margin:0"><head><style>
@font-face { font-family: Fixture; src: url("https://assets.test/font.ttf"); }
body { font-family: Fixture; }
</style></head><body style="margin:0">
<img id="hero" src="https://assets.test/fallback.svg"
srcset="https://assets.test/hero.svg 2x"
style="display:block;width:100px;height:auto">
<div style="position:sticky;top:0;height:10px;background:#00ff00"></div>
<div style="height:60px;background:#ff0000"></div>
<div style="height:180px;overflow:hidden;background:#0000ff;
background-image:url('https://assets.test/background.svg')">
<div style="position:sticky;top:5px;height:20px;background:#00ff00"></div>
<div style="transform:translate(3px,4px);height:80px;color:#ffffff">stable text</div>
</div>
<div id="fixed" style="position:fixed;top:2px;left:2px;width:8px;height:8px"></div>
</body></html>"#,
);
let viewport = (100.0, 80.0);
let counts = Arc::new(std::sync::Mutex::new(HashMap::<String, usize>::new()));
let loader_counts = Arc::clone(&counts);
let mut resources = RenderResourceCache::with_loader(move |url: &str| {
*loader_counts
.lock()
.expect("loader counts")
.entry(url.to_string())
.or_default() += 1;
match url {
"https://assets.test/font.ttf" => Some(FONT_BYTES.to_vec()),
"https://assets.test/hero.svg" => Some(
br##"<svg xmlns="http://www.w3.org/2000/svg" width="200" height="100">
<rect width="200" height="100" fill="#ffff00"/>
</svg>"##
.to_vec(),
),
"https://assets.test/background.svg" => Some(
br##"<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20">
<rect width="20" height="20" fill="#0000ff"/>
</svg>"##
.to_vec(),
),
_ => None,
}
});
let mut prepared =
prepare_dom(&tree, viewport, None, &mut resources).expect("prepared render");
let hero = tree
.query_selector("#hero")
.expect("valid selector")
.expect("hero");
assert_eq!(
prepared.selected_image(hero),
Some(&SelectedImage {
resolved_url: "https://assets.test/hero.svg".to_string(),
density: 2.0,
})
);
let hero_rect = prepared.layout().rects.get(&hero).expect("hero rect");
assert!((hero_rect.width - 100.0).abs() < 0.1);
assert!((hero_rect.height - 50.0).abs() < 0.1);
assert!(prepared.content_size().1 > viewport.1);
assert!(!prepared.sticky_layout().is_empty());
assert_eq!(
prepared.viewport_rect(hero, (0.0, 20.0)).unwrap().y,
prepared.document_rect(hero).unwrap().y - 20.0
);
let fixed = tree
.query_selector("#fixed")
.expect("valid selector")
.expect("fixed");
assert!(prepared.viewport_fixed_nodes().contains(&fixed));
assert_eq!(
prepared.viewport_rect(fixed, (0.0, 100.0)),
prepared.document_rect(fixed)
);
let base_rects = prepared.layout().rects.clone();
let base_translates = prepared.layout().translates.clone();
let base_clips = prepared.layout().clip_rects.clone();
let near = screenshot_prepared(
&tree,
&mut prepared,
&mut resources,
(0.0, 20.0),
)
.expect("near capture");
let far = screenshot_prepared(
&tree,
&mut prepared,
&mut resources,
(0.0, 100.0),
)
.expect("far capture");
let far_repeat = screenshot_prepared(
&tree,
&mut prepared,
&mut resources,
(0.0, 100.0),
)
.expect("repeated far capture");
let near_after_far = screenshot_prepared(
&tree,
&mut prepared,
&mut resources,
(0.0, 20.0),
)
.expect("repeated near capture");
assert_ne!(near, far, "distinct scroll positions must paint distinct frames");
assert_eq!(far, far_repeat, "the same scroll position must be stable");
assert_eq!(
near, near_after_far,
"an intervening capture must not accumulate scroll movement"
);
assert_eq!(prepared.layout().rects, base_rects);
assert_eq!(prepared.layout().translates, base_translates);
assert_eq!(prepared.layout().clip_rects, base_clips);
let counts = counts.lock().expect("final loader counts");
for url in [
"https://assets.test/font.ttf",
"https://assets.test/hero.svg",
"https://assets.test/background.svg",
] {
assert_eq!(counts.get(url), Some(&1), "{url} must load exactly once");
}
assert!(!counts.contains_key("https://assets.test/fallback.svg"));
assert_eq!(resources.retained_entry_count(), 3);
assert!(resources.retained_byte_len() > FONT_BYTES.len());
}
/// Portable pixel counterpart to the Chromium root-sticky geometry probe
/// in obscura-js. It checks that sticky backgrounds and descendants move
/// as one painted subtree, bottom sticking is visible, fixed remains
/// viewport-anchored, and the top sticky eventually exits at its
/// containing-block boundary.
#[test]
fn root_scroll_sticky_paints_subtrees_and_respects_bottom_boundary() {
let tree = parse_html(
r#"<html style="margin:0"><body style="margin:0;background:#220022">
<div style="height:40px;background:#ffffff"></div>
<div style="box-sizing:border-box;height:900px;padding:10px 12px;border:4px solid #333;background:#dddddd">
<div style="box-sizing:border-box;position:sticky;top:20px;height:60px;margin:6px;background:#ff0000">
<div style="height:12px;background:#0000ff"></div>
</div>
<div style="height:500px"></div>
<div style="box-sizing:border-box;position:sticky;bottom:15px;height:50px;margin:5px;background:#ff8800"></div>
</div>
<div style="height:700px;background:#220022"></div>
<div style="position:fixed;z-index:10;left:600px;top:20px;width:60px;height:60px;background:#00ff00"></div>
</body></html>"#,
);
let viewport = (800.0, 513.0);
let top = paint_dom_scrolled(&tree, viewport, None, (0.0, 0.0)).unwrap();
let stuck = paint_dom_scrolled(&tree, viewport, None, (0.0, 100.0)).unwrap();
let bottom_normal =
paint_dom_scrolled(&tree, viewport, None, (0.0, 400.0)).unwrap();
let boundary =
paint_dom_scrolled(&tree, viewport, None, (0.0, 9999.0)).unwrap();
let is_color = |pixel: tiny_skia::PremultipliedColorU8, rgb: [u8; 3]| {
(pixel.red() as i16 - rgb[0] as i16).abs() < 8
&& (pixel.green() as i16 - rgb[1] as i16).abs() < 8
&& (pixel.blue() as i16 - rgb[2] as i16).abs() < 8
};
assert!(is_color(top.pixel(100, 80).unwrap(), [255, 0, 0]));
assert!(is_color(top.pixel(100, 460).unwrap(), [255, 136, 0]));
assert!(is_color(stuck.pixel(100, 25).unwrap(), [0, 0, 255]));
assert!(is_color(stuck.pixel(100, 50).unwrap(), [255, 0, 0]));
assert!(is_color(stuck.pixel(100, 460).unwrap(), [255, 136, 0]));
assert!(is_color(
bottom_normal.pixel(100, 240).unwrap(),
[255, 136, 0]
));
assert!(is_color(boundary.pixel(100, 20).unwrap(), [34, 0, 34]));
for pixmap in [&top, &stuck, &bottom_normal, &boundary] {
assert!(is_color(pixmap.pixel(620, 30).unwrap(), [0, 255, 0]));
}
}
#[test]
fn object_fit_contain_and_cover_center_and_preserve_aspect() {
// A 200x100 box (2:1) with a square 100x100 image, offset so centering
// is checked against the box origin, not (0,0).
let box_rect = crate::Rect { x: 10.0, y: 20.0, width: 200.0, height: 100.0 };
let (iw, ih) = (100.0f32, 100.0f32);
// Contain: the largest square fitting inside 200x100 is 100x100,
// letterboxed horizontally and centered.
let c = object_fit_dest(&box_rect, iw, ih, crate::ObjectFit::Contain);
assert!((c.width - 100.0).abs() < 0.01 && (c.height - 100.0).abs() < 0.01, "contain size {:?}", c);
assert!((c.width / c.height - iw / ih).abs() < 1e-3, "contain preserves aspect: {:?}", c);
assert!((c.x - 60.0).abs() < 0.01, "contain centered x (10 + (200-100)/2): {}", c.x);
assert!((c.y - 20.0).abs() < 0.01, "contain centered y (20 + (100-100)/2): {}", c.y);
// Contain always fits inside the box.
assert!(c.x >= box_rect.x - 0.01 && c.x + c.width <= box_rect.x + box_rect.width + 0.01);
assert!(c.y >= box_rect.y - 0.01 && c.y + c.height <= box_rect.y + box_rect.height + 0.01);
// Cover: the smallest square covering 200x100 is 200x200, centered so
// it overflows the box vertically (the paint path clips it).
let v = object_fit_dest(&box_rect, iw, ih, crate::ObjectFit::Cover);
assert!((v.width - 200.0).abs() < 0.01 && (v.height - 200.0).abs() < 0.01, "cover size {:?}", v);
assert!((v.width / v.height - iw / ih).abs() < 1e-3, "cover preserves aspect: {:?}", v);
assert!((v.x - 10.0).abs() < 0.01, "cover centered x (10 + (200-200)/2): {}", v.x);
assert!((v.y + 30.0).abs() < 0.01, "cover centered y (20 + (100-200)/2 = -30): {}", v.y);
// Cover fully covers the box on both axes.
assert!(v.x <= box_rect.x + 0.01 && v.x + v.width >= box_rect.x + box_rect.width - 0.01);
assert!(v.y <= box_rect.y + 0.01 && v.y + v.height >= box_rect.y + box_rect.height - 0.01);
// scale-down never upscales: a 100x100 image in a 200x200 box stays
// 100x100 (Contain would grow it to 200x200), centered.
let box2 = crate::Rect { x: 0.0, y: 0.0, width: 200.0, height: 200.0 };
let sd = object_fit_dest(&box2, iw, ih, crate::ObjectFit::ScaleDown);
assert!((sd.width - 100.0).abs() < 0.01 && (sd.height - 100.0).abs() < 0.01, "scale-down no upscale: {:?}", sd);
assert!((sd.x - 50.0).abs() < 0.01 && (sd.y - 50.0).abs() < 0.01, "scale-down centered: {:?}", sd);
let cn = object_fit_dest(&box2, iw, ih, crate::ObjectFit::Contain);
assert!((cn.width - 200.0).abs() < 0.01, "contain upscales into the box: {:?}", cn);
// None uses the intrinsic size regardless of box, centered.
let n = object_fit_dest(&box2, iw, ih, crate::ObjectFit::None);
assert!((n.width - 100.0).abs() < 0.01 && (n.height - 100.0).abs() < 0.01, "none intrinsic size: {:?}", n);
assert!((n.x - 50.0).abs() < 0.01 && (n.y - 50.0).abs() < 0.01, "none centered: {:?}", n);
// Fill stretches to exactly the box.
let f = object_fit_dest(&box_rect, iw, ih, crate::ObjectFit::Fill);
assert!((f.width - box_rect.width).abs() < 0.01 && (f.height - box_rect.height).abs() < 0.01, "fill: {:?}", f);
assert!((f.x - box_rect.x).abs() < 0.01 && (f.y - box_rect.y).abs() < 0.01, "fill origin: {:?}", f);
}
#[test]
fn paints_background_color() {
let tree = parse_html(
"<html><body><div style=\"background-color: #ff0000; width: 100px; height: 80px\"></div></body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
assert_eq!(pixmap.width(), 200);
// The red div is laid out at the origin; sample inside it.
let inside = pixmap.pixel(10, 10).expect("pixel");
assert!(inside.red() > 200, "expected red bg, got {:?}", inside);
assert!(inside.green() < 60);
assert!(inside.blue() < 60);
// Outside the 100x80 div the page background is white.
let outside = pixmap.pixel(150, 150).expect("pixel");
assert_eq!(outside.red(), 255);
assert_eq!(outside.green(), 255);
assert_eq!(outside.blue(), 255);
}
#[test]
fn auto_background_size_uses_intrinsic_dimensions_and_position() {
let tree = parse_html(
r#"<html><body style="margin:0">
<div style="width:100px;height:100px;background-color:red;
background-image:url(&quot;data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='20'%20height='10'%3E%3Crect%20width='20'%20height='10'%20fill='blue'/%3E%3C/svg%3E&quot;);
background-position:right bottom;background-repeat:no-repeat"></div>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (120.0, 120.0), None).expect("pixmap");
let background = pixmap.pixel(10, 10).expect("pixel");
assert!(
background.red() > 200 && background.blue() < 60,
"the intrinsic image must not stretch across the owner"
);
let image = pixmap.pixel(90, 95).expect("pixel");
assert!(
image.blue() > 200 && image.red() < 60,
"the 20x10 intrinsic image must anchor at bottom right"
);
}
#[test]
fn contextual_background_size_preserves_auto_axis_ratio() {
let source = "data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='200'%20height='50'%3E%3C/svg%3E";
let owner = crate::Rect {
x: 0.0,
y: 0.0,
width: 132.0,
height: 60.0,
};
let mut cache = RenderResourceCache::default();
let image = background_image_rect(
source,
None,
&owner,
None,
Some("calc(100% - 2rem) auto"),
None,
(0.0, 0.5),
10.0,
10.0,
(1280.0, 720.0),
&mut cache,
)
.unwrap();
assert_eq!(image.width, 112.0);
assert_eq!(image.height, 28.0);
assert_eq!(image.y, 16.0);
}
#[test]
fn paints_positioned_empty_pseudo_background_box() {
let tree = parse_html(
r#"<html><head><style>
body { margin:0 }
#host { position:relative; width:100px; height:50px }
#host::before {
content:"";
position:absolute;
top:10px;
left:20px;
width:40px;
height:30px;
background:
linear-gradient(to bottom, transparent, #ffffff),
radial-gradient(circle at 50% 50%, #ebf3f9, #d6dee4);
}
</style></head><body><div id="host"></div></body></html>"#,
);
let pixmap = paint_dom(&tree, (120.0, 80.0), None).expect("pixmap");
let center = pixmap.pixel(40, 25).expect("pixel");
assert!(
center.red() >= 214 && center.green() >= 222 && center.blue() >= 228,
"transparent-to-white over a light radial layer must not darken it: {center:?}"
);
let outside = pixmap.pixel(5, 5).expect("pixel");
assert_eq!(
(outside.red(), outside.green(), outside.blue()),
(255, 255, 255)
);
}
#[test]
fn paints_generated_style_images_and_sizes_content_url_as_replaced_content() {
let tree = parse_html(
r#"<html><head><style>
body { margin:0 }
#host { position:relative; width:100px; height:40px }
#host::before {
content:""; position:absolute; left:0; top:0;
width:40px; height:40px;
background-image:url("data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='40'%20height='40'%3E%3Crect%20width='40'%20height='40'%20fill='blue'/%3E%3C/svg%3E");
background-size:100% 100%;
}
#host::after {
content:""; position:absolute; left:50px; top:0;
width:40px; height:40px; background-color:red;
mask-image:url("data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='40'%20height='40'%3E%3Ccircle%20cx='20'%20cy='20'%20r='16'%20fill='white'/%3E%3C/svg%3E");
mask-size:40px 40px; mask-repeat:no-repeat;
}
#content-image {
display:block;
content:url("data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='30'%20height='20'%3E%3Crect%20width='30'%20height='20'%20fill='lime'/%3E%3C/svg%3E");
}
</style></head><body>
<div id="host"></div><img id="content-image" alt="">
</body></html>"#,
);
// The first cascade exposes the style image. Feeding its decoded
// dimensions back through the ordinary intrinsic map must give the
// source-less replaced element its 30x20 CSS box.
let mut intrinsic = std::collections::HashMap::new();
let first = layout_dom_with_web_fonts(&tree, (120.0, 80.0), &intrinsic, &[]);
let host_id = tree
.query_selector("#host")
.expect("selector")
.expect("host");
let host_style = &first.styles[&host_id];
assert!(
host_style
.before_pseudo
.as_deref()
.and_then(|style| style.background_image.as_deref())
.is_some(),
"the positioned pseudo must retain its parsed URL background"
);
assert!(
host_style
.after_pseudo
.as_deref()
.and_then(|style| style.mask_image.as_deref())
.is_some(),
"the positioned pseudo must retain its parsed URL mask"
);
let host_rect = first.rects[&host_id];
assert_eq!(
(host_rect.x, host_rect.y, host_rect.width, host_rect.height),
(0.0, 0.0, 100.0, 40.0)
);
let mut cache = RenderResourceCache::default();
let mut selected = HashMap::new();
assert!(collect_content_image_intrinsics(
&tree,
&first.styles,
None,
&mut cache,
&mut intrinsic,
&mut selected,
));
let laid = layout_dom_with_web_fonts(&tree, (120.0, 80.0), &intrinsic, &[]);
let image_id = tree
.query_selector("#content-image")
.expect("selector")
.expect("content image");
let image_rect = laid.rects[&image_id];
assert_eq!(
(
image_rect.x,
image_rect.y,
image_rect.width,
image_rect.height
),
(0.0, 40.0, 30.0, 20.0),
"content:url must use ordinary replaced-element geometry"
);
let pixmap = paint_dom(&tree, (120.0, 80.0), None).expect("pixmap");
let blue = pixmap.pixel(20, 20).expect("blue pseudo");
assert!(
blue.blue() > 220 && blue.red() < 40 && blue.green() < 80,
"positioned pseudo background-image must paint: {blue:?}"
);
let red = pixmap.pixel(70, 20).expect("masked pseudo center");
assert!(
red.red() > 220 && red.green() < 40 && red.blue() < 40,
"positioned pseudo mask center must use the authored fill: {red:?}"
);
let transparent_corner = pixmap.pixel(51, 1).expect("mask corner");
assert_eq!(
(
transparent_corner.red(),
transparent_corner.green(),
transparent_corner.blue(),
),
(255, 255, 255),
"transparent mask corners must not paint the pseudo's solid box"
);
let green = pixmap.pixel(15, 50).expect("content image");
assert!(
green.green() > 220 && green.red() < 40 && green.blue() < 40,
"content:url image must paint through the replaced-image path: {green:?}"
);
}
#[test]
fn paints_empty_in_flow_generated_block_at_its_layout_rect() {
let tree = parse_html(
r#"<html><head><style>
html, body { margin:0 }
body { font-size:20px; line-height:20px }
#host { width:200px }
#host::before {
content:""; display:block; width:80px; height:40px;
margin-bottom:10px; background:#0066cc;
}
#next { width:20px; height:10px; background:#00aa00 }
</style></head><body>
<div id="host">TEXT</div><div id="next"></div>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (240.0, 100.0), None).expect("pixmap");
let generated = pixmap.pixel(40, 20).expect("generated block pixel");
assert!(
generated.blue() > 180 && generated.green() > 70 && generated.red() < 30,
"the anonymous generated box must paint its own background: {generated:?}"
);
let following = pixmap.pixel(10, 75).expect("following block pixel");
assert!(
following.green() > 120 && following.red() < 30 && following.blue() < 30,
"the following block must paint below the generated geometry: {following:?}"
);
}
#[test]
fn paints_positioned_attr_content_over_the_host_background() {
let tree = parse_html(
r#"<html><head><style>
body { margin:0 }
#cta {
position:relative; width:120px; height:40px; border:0;
padding:0; color:transparent; background:red;
}
#cta::before {
content:attr(data-label);
position:absolute; inset:1px;
display:flex; align-items:center; justify-content:center;
border-radius:4px; color:black; background:white;
}
</style></head><body>
<button id="cta" data-label="Get Started">Get Started</button>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (140.0, 60.0), None).expect("pixmap");
let inner = pixmap.pixel(5, 5).expect("inner pixel");
assert_eq!(
(inner.red(), inner.green(), inner.blue()),
(255, 255, 255),
"the generated box must cover the red host background"
);
let dark_pixels = (35..85)
.flat_map(|x| (8..32).map(move |y| (x, y)))
.filter(|&(x, y)| {
let pixel = pixmap.pixel(x, y).unwrap();
pixel.red() < 100 && pixel.green() < 100 && pixel.blue() < 100
})
.count();
assert!(dark_pixels > 10, "generated attr() text must be painted");
}
#[test]
fn later_positioned_pseudo_opaquely_covers_the_earlier_one() {
let tree = parse_html(
r#"<html><head><style>
body { margin:0 }
#cta {
position:relative; width:120px; height:40px; padding:0;
color:transparent; background:black;
}
#cta::before {
content:"before";
position:absolute; inset:1px;
display:flex; align-items:center; justify-content:center;
color:red; background:red;
}
#cta::after {
content:"after";
position:absolute; inset:1px;
display:flex; align-items:center; justify-content:center;
color:blue; background:white;
}
</style></head><body><button id="cta">host</button></body></html>"#,
);
let pixmap = paint_dom(&tree, (140.0, 60.0), None).expect("pixmap");
let inner = pixmap.pixel(5, 5).expect("inner pixel");
assert_eq!(
(inner.red(), inner.green(), inner.blue()),
(255, 255, 255),
"::after's opaque background must cover ::before"
);
let red_pixels = (1..119)
.flat_map(|x| (1..39).map(move |y| (x, y)))
.filter(|&(x, y)| {
let pixel = pixmap.pixel(x, y).unwrap();
pixel.red() > 180 && pixel.green() < 80 && pixel.blue() < 80
})
.count();
assert_eq!(red_pixels, 0, "::before must not bleed through ::after");
}
#[test]
fn native_select_paints_only_the_selected_label_and_arrow() {
let tree = parse_html(
r#"<html><body style="margin:0">
<select id="theme">
<option>Light</option>
<option selected>Dark</option>
</select>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (160.0, 60.0), None).expect("pixmap");
let dark_pixels = (0..120)
.flat_map(|x| (0..30).map(move |y| (x, y)))
.filter(|&(x, y)| {
let pixel = pixmap.pixel(x, y).unwrap();
pixel.red() < 100 && pixel.green() < 100 && pixel.blue() < 100
})
.count();
assert!(
dark_pixels > 20,
"selected label, border, and disclosure arrow should paint"
);
let select = tree.get_element_by_id("theme").unwrap();
assert_eq!(selected_option_label(&tree, select).as_deref(), Some("Dark"));
}
#[test]
fn later_element_paints_over_earlier() {
// A blue div nested inside a red one: both cover the origin, and blue
// (a descendant, later in tree order) paints over red.
let tree = parse_html(
"<html><body>\
<div style=\"background-color:red; width:100px; height:100px\">\
<div style=\"background-color:blue; width:50px; height:50px\"></div>\
</div>\
</body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let p = pixmap.pixel(5, 5).expect("pixel");
assert!(p.blue() > 200, "expected blue to paint over red, got {:?}", p);
}
#[test]
fn nested_translate_accumulates_through_subtree() {
// Parent red box (position:absolute at 0,0, 20x20) translated by
// (50,60). Child blue box (10x10, in-flow at the red box's origin)
// translated by an additional (30,0). The child's painted position must
// be the SUM of both translates, (50+30, 60+0) = (80,60), proving an
// ancestor's translate offsets the whole subtree on top of the node's
// own translate.
let tree = parse_html(
"<html><body style=\"margin:0\">\
<div style=\"position:relative; width:200px; height:200px\">\
<div style=\"position:absolute; top:0; left:0; width:20px; height:20px; \
background:#ff0000; transform:translate(50px,60px)\">\
<div style=\"width:10px; height:10px; background:#0000ff; \
transform:translate(30px,0)\"></div>\
</div>\
</div>\
</body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
// Child blue lands at (80..90, 60..70).
let blue = pixmap.pixel(85, 65).expect("pixel");
assert!(
blue.blue() > 200 && blue.red() < 60,
"expected blue child at accumulated offset (80,60), got {:?}",
blue
);
// Parent red lands at (50..70, 60..80); sample where the blue child does
// not cover.
let red = pixmap.pixel(55, 75).expect("pixel");
assert!(
red.red() > 200 && red.blue() < 60,
"expected red parent at its own translate (50,60), got {:?}",
red
);
// Nothing painted at the pre-transform origin: both boxes moved away.
let origin = pixmap.pixel(5, 5).expect("pixel");
assert_eq!((origin.red(), origin.green(), origin.blue()), (255, 255, 255));
}
#[test]
fn transformed_image_is_clipped_inside_overflow_border() {
// CSS overflow clipping belongs to the owner's padding box. The
// translated images paint after the viewport's border in tree order,
// so a border-box clip would let them overwrite the border.
let tree = parse_html(
r#"<html><body style="margin:0">
<div style="width:100px;height:60px;overflow:hidden;
border:4px solid red">
<div style="display:flex;transform:translate(-50px,0)">
<img alt="" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='100'%20height='60'%3E%3Crect%20width='100'%20height='60'%20fill='blue'/%3E%3C/svg%3E"
style="width:100px;height:60px;object-fit:cover;flex-shrink:0">
<img alt="" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='100'%20height='60'%3E%3Crect%20width='100'%20height='60'%20fill='blue'/%3E%3C/svg%3E"
style="width:100px;height:60px;object-fit:cover;flex-shrink:0">
</div>
</div>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (140.0, 90.0), None).expect("pixmap");
for &(x, y) in &[(0, 30), (3, 30), (104, 30), (107, 30), (50, 0), (50, 67)] {
let pixel = pixmap.pixel(x, y).expect("border pixel");
assert!(
pixel.red() > 220 && pixel.green() < 40 && pixel.blue() < 40,
"translated image must not overwrite border pixel ({x},{y}): {pixel:?}"
);
}
let content = pixmap.pixel(50, 30).expect("content pixel");
assert!(
content.blue() > 220 && content.red() < 40,
"translated cover image must remain visible inside padding box: {content:?}"
);
}
#[test]
fn projected_image_transform_enters_overflow_clip() {
// Chromium reduction: without the projected rotate/scale, this image is
// wholly left of the clip. Its transformed right edge reaches x=53.14.
let tree = parse_html(
r#"<html><body style="margin:0">
<div style="position:relative;width:120px;height:100px;overflow:hidden">
<div style="position:absolute;left:-60px;top:50px;transform-origin:0 0;
transform:rotateX(60deg) rotateZ(-45deg);scale:200%">
<img alt="" src="data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20width='40'%20height='40'%3E%3Crect%20width='40'%20height='40'%20fill='red'/%3E%3C/svg%3E"
style="display:block;width:40px;height:40px">
</div>
</div>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (160.0, 120.0), None).expect("pixmap");
assert!(
(0..100).any(|y| (0..120).any(|x| {
let pixel = pixmap.pixel(x, y).expect("inside viewport");
pixel.red() > 220 && pixel.green() < 40 && pixel.blue() < 40
})),
"projected image should enter the overflow clip"
);
assert!(
(0..120).all(|y| (120..160).all(|x| {
let pixel = pixmap.pixel(x, y).expect("outside clip");
pixel.red() > 240 && pixel.green() > 240 && pixel.blue() > 240
})),
"projected image must remain clipped to its overflow ancestor"
);
}
#[test]
fn translate_offscreen_box_is_not_painted() {
// translate(-10000px,0) shoves the box far off the left edge (the old
// hidden skip-link idiom); it must not paint anywhere on the canvas.
let tree = parse_html(
"<html><body>\
<div style=\"position:absolute; top:0; left:0; width:50px; height:50px; \
background:#ff0000; transform:translate(-10000px,0)\"></div>\
</body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let mut any_red = false;
'scan: for y in 0..200 {
for x in 0..200 {
let p = pixmap.pixel(x, y).expect("pixel");
if p.red() > 200 && p.green() < 60 && p.blue() < 60 {
any_red = true;
break 'scan;
}
}
}
assert!(!any_red, "translate(-10000px,0) box should be off-screen and unpainted");
}
#[test]
fn translate_percent_centers_absolute_box() {
// The canonical centering idiom: an absolutely-positioned box at
// top:50%/left:50% of its containing block pulled back by
// translate(-50%,-50%) of its own size centers within it. In a 200x200
// container a 40x40 box centers at (100,100), so its border box (with
// top-left at 100,100 before the transform) becomes (80..120, 80..120).
let tree = parse_html(
"<html><body style=\"margin:0\">\
<div style=\"position:relative; width:200px; height:200px\">\
<div style=\"position:absolute; top:50%; left:50%; width:40px; height:40px; \
background:#ff0000; transform:translate(-50%,-50%)\"></div>\
</div>\
</body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let center = pixmap.pixel(100, 100).expect("pixel");
assert!(center.red() > 200 && center.blue() < 60, "expected centered red box, got {:?}", center);
// Just outside the centered box stays white.
let outside = pixmap.pixel(70, 70).expect("pixel");
assert_eq!((outside.red(), outside.green(), outside.blue()), (255, 255, 255));
}
#[test]
fn paints_text_color() {
let tree = parse_html(
"<html><body><div style=\"color: #00ff00; width: 100px; height: 100px\">Hello</div></body></html>",
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let mut found_green = false;
for y in 0..200 {
for x in 0..200 {
let p = pixmap.pixel(x, y).expect("pixel");
if p.green() > 200 && p.red() < 50 && p.blue() < 50 {
found_green = true;
break;
}
}
if found_green { break; }
}
assert!(found_green, "expected green text to be painted");
}
#[test]
fn word_measurement_honors_generic_font_family() {
let sans = measure_text("iiiiiiii", 16.0, false, Some("sans-serif"));
let mono = measure_text("iiiiiiii", 16.0, false, Some("monospace"));
assert!(
mono > sans * 1.5,
"monospace advances must be used for code text: sans={sans}, mono={mono}"
);
}
#[test]
fn paints_vendor_gradient_on_inline_text_span() {
// Vue and many other framework sites put the gradient on an inline
// accent span, not on the whole heading. The surrounding text must
// keep its normal color while this span samples both gradient ends.
let tree = parse_html(
r#"<html><head><style>
h1 { color:#17233c; font-size:50px; margin:0 }
html:not(.dark) .accent[data-v-x] {
-webkit-text-fill-color:transparent;
background:-webkit-linear-gradient(315deg,#42d392 25%,#647eff);
-webkit-background-clip:text;
background-clip:text
}
</style></head><body style="margin:0">
<h1>The <span class="accent" data-v-x>Progressive</span></h1>
</body></html>"#,
);
let pixmap = paint_dom(&tree, (500.0, 100.0), None).expect("pixmap");
let mut green = false;
let mut blue = false;
let mut normal = false;
for pixel in pixmap.pixels() {
let (r, g, b) = (pixel.red(), pixel.green(), pixel.blue());
green |= g > r.saturating_add(20) && g > b.saturating_add(10);
blue |= b > r.saturating_add(20) && b > g.saturating_add(5);
normal |= b > g.saturating_add(10) && r < 80 && g < 100;
}
assert!(normal, "surrounding heading text should retain its normal color");
assert!(green && blue, "inline accent should contain both gradient colors");
}
#[test]
fn serializes_inline_svg_subtree() {
// A sprite-style svg: a <use> that references a <symbol> in the same
// document must survive serialization so resvg can resolve it.
let tree = parse_html(
r##"<html><body><svg viewBox="0 0 10 10"><use href="#a"/><symbol id="a"><path d="M0 0h10v10z"/></symbol></svg></body></html>"##,
);
let svg = tree.query_selector("svg").unwrap().unwrap();
let out = serialize_svg(&tree, svg);
assert!(out.starts_with("<svg"), "root svg tag: {out}");
assert!(out.contains(r#"viewBox="0 0 10 10""#), "viewBox preserved: {out}");
assert!(out.contains(r#"xmlns="http://www.w3.org/2000/svg""#), "xmlns injected: {out}");
assert!(out.contains("<use") && out.contains(r##"href="#a""##), "use + href: {out}");
assert!(out.contains("<symbol") && out.contains(r#"id="a""#), "symbol id: {out}");
assert!(out.contains("<path") && out.contains("</path>"), "path opened + closed: {out}");
assert!(out.trim_end().ends_with("</svg>"), "root closed: {out}");
// The serialized string parses as a standalone SVG document.
let opts = usvg::Options::default();
assert!(
usvg::Tree::from_data(out.as_bytes(), &opts).is_ok(),
"usvg should parse serialized svg: {out}",
);
}
#[test]
fn inline_svg_keeps_author_css_and_embedded_text_fonts() {
// Inline SVG is parsed in the HTML document and styled by the page's
// author sheet, then serialized into a standalone document for resvg.
// The standalone boundary must not erase a CSS fill/font and inherit
// the root's `fill:none`, which made text-only illustrations blank.
let tree = parse_html(
r##"<html><head><style>
.art > text {
fill:#00cc55;
font-family:sans-serif;
font-size:24px;
font-weight:400
}
</style></head><body style="margin:0">
<svg class="art" width="120" height="50"
viewBox="0 0 120 50" fill="none">
<text x="4" y="32">SVG text</text>
</svg>
</body></html>"##,
);
let svg = tree.query_selector("svg").unwrap().unwrap();
let layout = crate::dom::layout_dom(&tree, (160.0, 80.0));
let markup = serialize_svg_styled(&tree, svg, &layout.styles);
assert!(
markup.contains("fill:#00cc55!important"),
"computed author fill must cross the standalone boundary: {markup}"
);
assert!(
markup.contains("font-size:24px!important"),
"computed SVG font size must cross the standalone boundary: {markup}"
);
let pixmap = paint_dom(&tree, (160.0, 80.0), None).expect("pixmap");
let painted_green = pixmap
.pixels()
.iter()
.any(|pixel| pixel.green() > 150 && pixel.red() < 80 && pixel.blue() < 120);
assert!(
painted_green,
"author-styled SVG text should rasterize with embedded fonts"
);
}
#[test]
fn injects_xmlns_only_when_absent() {
let tree = parse_html(
r#"<html><body><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 4 4"><rect width="4" height="4"/></svg></body></html>"#,
);
let svg = tree.query_selector("svg").unwrap().unwrap();
let out = serialize_svg(&tree, svg);
assert_eq!(out.matches("xmlns=").count(), 1, "no duplicate xmlns: {out}");
}
#[test]
fn paints_inline_svg() {
// The <rect> inside an inline svg must rasterize (it is not an <img>).
let tree = parse_html(
r##"<html><body><svg width="40" height="40" viewBox="0 0 40 40"><rect x="0" y="0" width="40" height="40" fill="#ff0000"/></svg></body></html>"##,
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let mut found_red = false;
'outer: for y in 0..80 {
for x in 0..80 {
let p = pixmap.pixel(x, y).expect("pixel");
if p.red() > 200 && p.green() < 60 && p.blue() < 60 {
found_red = true;
break 'outer;
}
}
}
assert!(found_red, "expected inline svg <rect> to paint red");
}
#[test]
fn svg_missing_root_height_uses_the_final_css_viewport() {
let svg = br##"<svg xmlns="http://www.w3.org/2000/svg"
width="32" viewBox="0 0 223 236">
<rect width="223" height="236" fill="#ed174c"/>
</svg>"##;
let pixmap = render_svg(svg, 32, 34).expect("svg raster");
let mut min_y = 34u32;
let mut max_y = 0u32;
for y in 0..34 {
for x in 0..32 {
let pixel = pixmap.pixel(x, y).unwrap();
if pixel.alpha() > 0 {
min_y = min_y.min(y);
max_y = max_y.max(y);
}
}
}
assert!(
max_y.saturating_sub(min_y) >= 30,
"viewBox artwork should fill the resolved 32x34 viewport, got rows {min_y}..{max_y}"
);
}
#[test]
fn paints_inline_svg_current_color_from_computed_style() {
let tree = parse_html(
r##"<html><body><svg style="color:#0784aa" width="40" height="40" viewBox="0 0 40 40"><circle cx="20" cy="20" r="18" fill="currentColor"/></svg></body></html>"##,
);
let pixmap = paint_dom(&tree, (80.0, 80.0), None).expect("pixmap");
let mut found = false;
for pixel in pixmap.pixels() {
found |= pixel.blue() > 120 && pixel.green() > 80 && pixel.red() < 40;
}
assert!(found, "computed color should resolve currentColor in inline svg");
}
#[test]
fn paints_inline_svg_with_framework_colon_attribute() {
let tree = obscura_dom::parse_html(
r##"<html><body><svg q:id="f" width="40" height="40" viewBox="0 0 40 40"><rect width="40" height="40" fill="#18b6f6"/></svg></body></html>"##,
);
let output = paint_dom(&tree, (80.0, 80.0), None).expect("pixmap");
let found_blue = (0..80).any(|y| {
(0..80).any(|x| {
let pixel = output.pixel(x, y).expect("pixel");
pixel.blue() > 200 && pixel.green() > 120 && pixel.red() < 80
})
});
assert!(
found_blue,
"framework hydration attributes must not invalidate inline SVG XML"
);
}
#[test]
fn paints_inline_svg_use_reference() {
// The icon-sprite pattern: <use href="#id"> resolves against a <defs>
// element in the same svg only because the whole subtree is serialized
// and handed to resvg as one document.
let tree = parse_html(
r##"<html><body><svg width="40" height="40" viewBox="0 0 40 40"><defs><rect id="a" width="40" height="40" fill="#0000ff"/></defs><use href="#a"/></svg></body></html>"##,
);
let pixmap = paint_dom(&tree, (200.0, 200.0), None).expect("pixmap");
let mut found_blue = false;
'outer: for y in 0..80 {
for x in 0..80 {
let p = pixmap.pixel(x, y).expect("pixel");
if p.blue() > 200 && p.red() < 60 && p.green() < 60 {
found_blue = true;
break 'outer;
}
}
}
assert!(found_blue, "expected <use> to instantiate the referenced <rect>");
}
#[test]
fn extracts_symbol_by_id_from_sprite() {
// The external-sprite core: given a fetched sprite, pull out just the
// referenced <symbol> verbatim so it can be spliced into the local svg.
let sprite = r##"<svg xmlns="http://www.w3.org/2000/svg"><defs><symbol id="a" viewBox="0 0 10 10"><path d="M0 0h10v10z"/></symbol><symbol id="b"><rect width="4" height="4"/></symbol></defs></svg>"##;
let out = extract_svg_element_by_id(sprite, "a").expect("symbol a found");
assert!(out.starts_with("<symbol"), "starts at the symbol tag: {out}");
assert!(out.contains(r#"id="a""#), "keeps the id: {out}");
assert!(out.contains("<path") && out.contains("h10v10z"), "keeps children: {out}");
assert!(out.trim_end().ends_with("</symbol>"), "closed at matching end: {out}");
assert!(!out.contains(r#"id="b""#), "stops before the sibling symbol: {out}");
assert!(!out.contains("<rect"), "no sibling content leaks in: {out}");
}
#[test]
fn extract_handles_self_closing_nesting_and_absent() {
// A self-closing element carrying the id returns just that tag.
let s1 = r#"<svg><rect id="x" width="4" height="4"/></svg>"#;
assert_eq!(
extract_svg_element_by_id(s1, "x").as_deref(),
Some(r#"<rect id="x" width="4" height="4"/>"#),
);
// Same-name nesting: the matching close is the outer one, not the inner.
let s2 = r#"<svg><g id="grp"><g><path/></g></g></svg>"#;
assert_eq!(
extract_svg_element_by_id(s2, "grp").as_deref(),
Some(r#"<g id="grp"><g><path/></g></g>"#),
);
// `data-id` / a missing id must not be mistaken for `id`.
let s3 = r#"<svg><symbol data-id="a"><path/></symbol></svg>"#;
assert!(extract_svg_element_by_id(s3, "a").is_none(), "data-id is not id");
assert!(extract_svg_element_by_id(s2, "nope").is_none(), "absent id");
}
#[test]
fn same_document_use_left_unchanged_by_inject() {
// A same-document symbol already inside the target SVG needs no
// injection and leaves the serialized markup byte-for-byte unchanged.
let tree = parse_html(
r##"<html><body><svg viewBox="0 0 10 10"><use href="#a"/><symbol id="a"><path d="M0 0h10v10z"/></symbol></svg></body></html>"##,
);
let svg = tree.query_selector("svg").unwrap().unwrap();
let mut markup = serialize_svg(&tree, svg);
let before = markup.clone();
let mut cache = RenderResourceCache::default();
let mut sprite_cache = std::collections::HashMap::new();
inject_external_sprites(&tree, svg, None, &mut markup, &mut cache, &mut sprite_cache);
assert_eq!(markup, before, "same-document use must be untouched");
}
#[test]
fn injects_document_level_symbol_into_target_svg() {
// Frameworks commonly keep one hidden sprite beside the application
// root and reference it from otherwise independent inline SVGs.
let tree = parse_html(
r##"<html><body>
<svg style="display:none"><symbol id="arrow" viewBox="0 0 10 10"><path d="M0 0h10v10z"/></symbol></svg>
<svg id="icon" viewBox="0 0 10 10"><use href="#arrow"/></svg>
</body></html>"##,
);
let svg = tree.query_selector("#icon").unwrap().unwrap();
let mut markup = serialize_svg(&tree, svg);
let mut cache = RenderResourceCache::default();
let mut sprite_cache = std::collections::HashMap::new();
inject_external_sprites(&tree, svg, None, &mut markup, &mut cache, &mut sprite_cache);
assert!(
markup.contains(r#"<defs><symbol id="arrow""#),
"document-level symbol must be copied into target SVG: {markup}"
);
assert!(
markup.contains(r##"<use href="#arrow""##),
"local use reference must remain intact: {markup}"
);
}
#[test]
fn injected_document_symbol_inherits_target_current_color() {
let tree = parse_html(
r##"<html><body>
<svg style="display:none"><symbol id="arrow" viewBox="0 0 10 10"><rect width="10" height="10" fill="currentColor"/></symbol></svg>
<svg id="icon" viewBox="0 0 10 10"><use href="#arrow"/></svg>
</body></html>"##,
);
let svg = tree.query_selector("#icon").unwrap().unwrap();
let mut markup = serialize_svg(&tree, svg);
let mut cache = RenderResourceCache::default();
let mut sprite_cache = std::collections::HashMap::new();
inject_external_sprites(&tree, svg, None, &mut markup, &mut cache, &mut sprite_cache);
inject_svg_current_color(&mut markup, [220, 20, 60, 255]);
let pixmap = render_svg(markup.as_bytes(), 20, 20).expect("injected svg renders");
assert!(
pixmap
.pixels()
.iter()
.any(|pixel| pixel.red() > 180 && pixel.green() < 60 && pixel.blue() < 100),
"injected currentColor symbol should inherit target SVG color: {markup}",
);
}
#[test]
fn svg_light_dark_presentation_is_resolved_before_usvg() {
let tree = parse_html(
r#"<style>
#dark { color-scheme:dark }
#dark rect {
fill:light-dark(#c3c7cb,#51565d);
stroke:light-dark(#ffffff,#000000);
}
</style>
<div id="dark">
<svg id="icon" width="10" height="10" viewBox="0 0 10 10">
<rect width="10" height="10"/>
</svg>
</div>"#,
);
let laid = crate::dom::layout_dom(&tree, (100.0, 100.0));
let svg = tree.query_selector("#icon").unwrap().unwrap();
let markup = serialize_svg_styled(&tree, svg, &laid.styles);
assert!(
!markup.to_ascii_lowercase().contains("light-dark("),
"unsupported CSS Color 5 syntax must not reach usvg: {markup}"
);
assert!(
markup.contains("fill:#51565dff!important")
&& markup.contains("stroke:#000000ff!important"),
"serialized presentation colors must use the dark subtree scheme: {markup}"
);
let pixmap =
render_svg(markup.as_bytes(), 10, 10).expect("resolved SVG renders");
let center = pixmap.pixel(5, 5).expect("center pixel");
assert!(
center.red() > 60
&& center.red() < 110
&& center.green() > 60
&& center.green() < 120
&& center.blue() > 70
&& center.blue() < 130,
"resolved dark fill must survive usvg rasterization: {center:?}"
);
}
#[test]
fn font_face_parser_selects_ascii_subset_and_preserves_functional_src() {
let css = r#"
@font-face {
font-family: "Example";
src: local("Example"), url("./example-cyrillic.woff2") format("woff2");
unicode-range: U+0400-04FF;
}
@font-face {
font-family: "Example";
font-style: italic;
font-weight: 350 650;
src: url(data:font/woff2;base64,d09GMg==) format("woff2"),
url("./example-latin.woff") format("woff");
unicode-range: U+??, U+2000-206F;
}
"#;
let faces = font_face_blocks(css);
assert_eq!(faces.len(), 2);
assert!(!font_face_covers_ascii(faces[0]));
assert!(font_face_covers_ascii(faces[1]));
assert_eq!(font_face_family(faces[1]).as_deref(), Some("Example"));
assert_eq!(font_face_weight(faces[1]), Some((350, 650)));
assert_eq!(font_face_italic(faces[1]), Some(true));
assert_eq!(
font_face_urls(faces[1]),
vec![
"data:font/woff2;base64,d09GMg==".to_string(),
"./example-latin.woff".to_string(),
]
);
}
#[test]
fn font_face_without_unicode_range_is_general_purpose() {
let css = r#"@font-face{font-family:Example;src:url(example.otf)}"#;
let face = font_face_blocks(css)[0];
assert!(font_face_covers_ascii(face));
assert_eq!(font_face_urls(face), vec!["example.otf"]);
}
}
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