918 lines
39 KiB
Rust
918 lines
39 KiB
Rust
//! obscura-render: the optional scoped render layer for Obscura.
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//!
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//! Obscura's default build has no layout or paint engine, which is the source
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//! of its speed and low memory. This crate adds a render layer behind a feature
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//! flag: real CSS box geometry (so getBoundingClientRect, elementFromPoint, and
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//! IntersectionObserver return true values) and, with the paint feature,
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//! rasterized PNG screenshots.
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//!
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//! Phase 1 (this file): the layout core. A `LayoutNode` tree plus a viewport is
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//! laid out with taffy and the resulting border-box geometry is returned per
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//! node. Later phases build the `LayoutNode` tree from the live DOM + computed
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//! styles, feed geometry back to JS, and add text + paint.
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use taffy::prelude::*;
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pub mod css;
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pub use css::Stylesheet;
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pub mod style;
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pub use style::compute_style;
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pub mod dom;
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pub use dom::{layout_dom, layout_dom_with_images, DomLayout};
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#[cfg(feature = "paint")]
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mod paint;
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#[cfg(feature = "paint")]
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pub use paint::{paint_dom, screenshot_png};
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// Real inline text layout (cosmic-text) lives behind the paint feature; the
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// layout-only build keeps the lighter word-split geometry. The stub lets
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// `dom.rs` name `inline::TextEngine` and call `try_build` unconditionally.
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#[cfg(feature = "paint")]
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pub mod inline;
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#[cfg(not(feature = "paint"))]
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pub mod inline {
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use obscura_dom::tree::{DomTree, NodeId};
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use std::collections::HashMap;
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#[derive(Default)]
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pub struct TextEngine;
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impl TextEngine {
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pub fn new() -> Self {
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TextEngine
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}
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/// Layout-only builds have no shaper, so no container is ever treated
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/// as a cosmic-text inline formatting context: the word-split path
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/// handles text geometry for `getBoundingClientRect`.
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pub fn try_build(&mut self, _tree: &DomTree, _id: NodeId, _styles: &HashMap<NodeId, crate::LayoutStyle>) -> Option<usize> {
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None
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}
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/// See `try_build`: inline runs likewise fall back to word-split
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/// geometry in layout-only builds.
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pub fn try_build_run(
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&mut self,
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_tree: &DomTree,
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_parent: NodeId,
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_run: &[NodeId],
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_styles: &HashMap<NodeId, crate::LayoutStyle>,
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) -> Option<usize> {
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None
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}
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}
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}
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/// An axis-aligned rectangle in CSS pixels, relative to the containing block.
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#[derive(Debug, Clone, Copy, Default, PartialEq)]
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pub struct Rect {
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pub x: f32,
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pub y: f32,
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pub width: f32,
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pub height: f32,
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}
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impl Rect {
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/// The overlap of two rects, or `None` if they do not intersect (or the
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/// overlap is degenerate). Used to accumulate an ancestor clip chain for
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/// `overflow: hidden`.
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pub fn intersect(&self, other: &Rect) -> Option<Rect> {
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let x0 = self.x.max(other.x);
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let y0 = self.y.max(other.y);
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let x1 = (self.x + self.width).min(other.x + other.width);
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let y1 = (self.y + self.height).min(other.y + other.height);
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if x1 > x0 && y1 > y0 {
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Some(Rect { x: x0, y: y0, width: x1 - x0, height: y1 - y0 })
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} else {
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None
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}
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}
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/// The smallest rect covering both. Used to derive a table row/section box
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/// from its cells, since `<tr>`/`<tbody>` are not laid out as taffy boxes.
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pub fn union(&self, other: &Rect) -> Rect {
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let x0 = self.x.min(other.x);
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let y0 = self.y.min(other.y);
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let x1 = (self.x + self.width).max(other.x + other.width);
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let y1 = (self.y + self.height).max(other.y + other.height);
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Rect { x: x0, y: y0, width: x1 - x0, height: y1 - y0 }
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}
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}
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/// Per-edge box values (margin / padding / border) in CSS pixels.
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#[derive(Debug, Clone, Copy, Default, PartialEq)]
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pub struct Edges {
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pub top: f32,
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pub right: f32,
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pub bottom: f32,
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pub left: f32,
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}
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/// The display modes obscura-render cares about for phase 1. Inline text layout
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/// arrives with the text/paint phase and is folded in then.
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#[derive(Debug, Clone, Copy, Default, PartialEq)]
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pub enum Display {
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#[default]
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Block,
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Flex,
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Grid,
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Inline,
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#[allow(dead_code)]
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None,
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}
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#[derive(Debug, Clone, Copy, Default, PartialEq)]
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pub enum Dimension {
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#[default]
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Auto,
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Px(f32),
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/// 0.0-1.0 fraction of the containing block.
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Percent(f32),
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/// Font-relative and viewport-relative units, kept unresolved at parse
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/// time (the element font-size and viewport are not known then) and
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/// resolved to `Px` during `dom::layout_dom`'s top-down pass via
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/// [`Dimension::resolve`]. Resolving em/rem/vw against a hardcoded 16px at
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/// parse time (the old behavior) silently corrupted every relative length.
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Em(f32),
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Rem(f32),
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Vw(f32),
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Vh(f32),
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Vmin(f32),
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Vmax(f32),
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}
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impl Dimension {
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/// Resolve font/viewport-relative units to `Px`. `em_px` is the element's
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/// own font-size, `rem_px` the root's, and `vw`/`vh` are one hundredth of
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/// the viewport width/height. `Px`, `Percent`, and `Auto` pass through
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/// (`Percent` stays for taffy to resolve against the containing block).
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pub fn resolve(self, em_px: f32, rem_px: f32, vw: f32, vh: f32) -> Dimension {
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match self {
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Dimension::Em(v) => Dimension::Px(v * em_px),
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Dimension::Rem(v) => Dimension::Px(v * rem_px),
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Dimension::Vw(v) => Dimension::Px(v * vw),
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Dimension::Vh(v) => Dimension::Px(v * vh),
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Dimension::Vmin(v) => Dimension::Px(v * vw.min(vh)),
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Dimension::Vmax(v) => Dimension::Px(v * vw.max(vh)),
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other => other,
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}
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}
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}
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/// The subset of CSS that influences box layout. Expanded in later phases.
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#[derive(Debug, Clone, Default)]
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pub struct LayoutStyle {
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pub display: Display,
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pub width: Dimension,
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pub height: Dimension,
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/// Which box edge `width`/`height` and min/max sizes describe. CSS starts
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/// at `content-box`; many modern reset sheets opt into `border-box`.
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pub box_sizing: BoxSizing,
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/// Whether `width`/`height` was set by an author rule (including an explicit
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/// `auto`). Presentational `width`/`height` HTML attributes are a lower
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/// priority than author CSS, so they apply only when these are false; an
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/// explicit `width:auto` must still suppress a `width="408"` attribute so
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/// the element keeps its aspect-ratio size instead of the intrinsic one.
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pub width_set: bool,
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pub height_set: bool,
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pub min_width: Dimension,
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pub min_height: Dimension,
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pub max_width: Dimension,
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pub max_height: Dimension,
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/// `aspect-ratio` as width/height, or an image's intrinsic ratio resolved
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/// at layout. Lets a replaced element (or a padding-box card) derive the
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/// missing dimension from the given one, so a `width:100%` image gets a
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/// real height instead of collapsing to zero.
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pub aspect_ratio: Option<f32>,
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pub margin: Edges,
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/// Which margin sides are `auto` (top, right, bottom, left). `margin: 0
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/// auto` / `margin-inline: auto` centering needs a real Auto margin, which
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/// the f32 `margin` cannot express; this flag drives it at taffy mapping.
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pub margin_auto: [bool; 4],
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/// Percentage margin per side (top, right, bottom, left) as a 0..1 fraction,
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/// `None` when the side is a fixed length. Like padding, every side resolves
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/// against the containing block's WIDTH; the f32 `margin` cannot carry a
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/// percentage, so this is resolved to px during `dom::layout_dom`'s top-down
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/// pass once the containing-block width is known.
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pub margin_percent: [Option<f32>; 4],
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/// Font- and viewport-relative margin lengths (top, right, bottom, left).
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/// These retain their unit until the top-down pass knows the element font
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/// size, root font size, and viewport dimensions.
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pub margin_relative: [Option<Dimension>; 4],
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pub padding: Edges,
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/// Percentage padding per side (top, right, bottom, left) as a 0..1
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/// fraction, `None` when the side is a fixed length. All four sides resolve
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/// against the containing block's WIDTH (per CSS, including top/bottom): this
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/// is the responsive aspect-ratio-box trick (`padding-top:56.25%` reserves a
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/// 16:9 area). The f32 `padding` cannot carry a percentage, so it is
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/// resolved to px in `dom::layout_dom`'s top-down pass and written back into
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/// `padding`, which then feeds taffy as a fixed length.
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pub padding_percent: [Option<f32>; 4],
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/// Font- and viewport-relative padding lengths (top, right, bottom, left),
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/// resolved alongside `margin_relative` during the top-down pass.
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pub padding_relative: [Option<Dimension>; 4],
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pub border: Edges,
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/// `border-radius` (uniform; the first value of the shorthand). Rounds the
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/// background fill and border. In px after resolution.
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pub border_radius: f32,
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/// RGBA for the paint step. Parsed always (cheap), used only with `paint`.
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pub background_color: Option<[u8; 4]>,
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/// `linear-gradient(...)` background: (angle in degrees clockwise from 12
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/// o'clock per CSS, list of (rgba, optional 0..1 stop position)). Modern
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/// hero sections use gradients heavily; without this they paint white.
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pub background_gradient: Option<(f32, Vec<([u8; 4], Option<f32>)>)>,
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/// The first `url(...)` reference from `background`/`background-image`
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/// (gradients and repeat keywords in the same shorthand are ignored: we
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/// paint the referenced image, not the gradient layer).
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pub background_image: Option<String>,
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/// `background-size`, in px, when given as explicit length(s) (a bare
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/// `10px` applies to both axes, matching how small square icons are
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/// almost always sized). `None` means "fill the whole box" (our fallback
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/// when the value is a keyword we don't evaluate, `cover`/`contain`, or
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/// absent with an already icon-sized box like the HN vote arrow).
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pub background_size: Option<(f32, f32)>,
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/// `background-position` as a 0.0-1.0 fraction per axis (0,0 = default
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/// top-left; 1,0.5 = "right center"). Only meaningful alongside
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/// `background_size`: without a known image size there is no leftover
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/// box space to position within.
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pub background_position: (f32, f32),
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/// `background-clip: text` / `-webkit-background-clip: text`: the background
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/// paints only through the element's glyphs, not as a filled box. Combined
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/// with a transparent text color this is the common gradient-text technique
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/// (hero headings, buttons like astro.build's "Get Started"); without
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/// honoring it those labels paint invisible. Consumed in the text paint path
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/// (`inline::TextEngine` fills glyphs from the background; `paint` suppresses
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/// the box fill so the gradient does not paint as a rectangle).
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pub background_clip_text: bool,
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/// `mask-image`/`-webkit-mask-image: url(...)`: the ubiquitous "colored,
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/// scalable icon" pattern (an SVG shape used as a stencil, tinted by
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/// `background-color`/`color` instead of carrying its own colors). Without
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/// this, every such icon paints as a solid filled square.
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pub mask_image: Option<String>,
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/// Foreground (text) color for the paint step.
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pub color: Option<[u8; 4]>,
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pub border_color: Option<[u8; 4]>,
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pub font_size: Option<f32>,
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/// `font-size` given in a font/viewport-relative unit, resolved to
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/// `font_size` (px) during the inheritance pass against the parent and
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/// root font-sizes. `None` when font-size was absolute or unset.
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pub font_size_raw: Option<Dimension>,
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pub font_weight: Option<String>,
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/// The computed `font-family` list, lowercased. Inherited. The text engine
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/// resolves it to a bundled face (Liberation Sans/Serif/Mono) the way
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/// Chromium picks a generic family on this host.
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pub font_family: Option<String>,
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pub align_items: Option<taffy::AlignItems>,
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pub flex_direction: Option<taffy::FlexDirection>,
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pub flex_wrap: Option<taffy::FlexWrap>,
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pub justify_content: Option<taffy::JustifyContent>,
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pub flex_grow: Option<f32>,
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pub flex_shrink: Option<f32>,
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/// `flex-basis` (longhand, or the length in a `flex:` shorthand). `Auto`
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/// is the default. Fixed-basis sidebars/columns (`flex: 0 0 260px`)
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/// collapse to content width without it.
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pub flex_basis: Dimension,
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// CSS Grid. Tracks are stored as taffy sizing functions; `grid_areas` is the
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// parsed `grid-template-areas` matrix (one Vec per row, `.` for a null cell),
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// resolved to line placements on children in a later pass.
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pub grid_template_columns: Vec<taffy::TrackSizingFunction>,
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pub grid_template_rows: Vec<taffy::TrackSizingFunction>,
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pub grid_areas: Option<Vec<Vec<String>>>,
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pub grid_area_name: Option<String>,
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pub grid_column: Option<taffy::Line<taffy::GridPlacement>>,
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pub grid_row: Option<taffy::Line<taffy::GridPlacement>>,
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/// `[line-name]` -> 1-based grid line number, parsed from
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/// `grid-template-columns`/`-rows`. taffy has no native named-line support,
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/// so children placed by name (`grid-column: content-start / content-end`,
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/// widely used by the Guardian and other editorial grids) are resolved to
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/// numeric lines against these maps in `dom::resolve_grid_areas`.
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pub grid_col_line_names: Option<std::collections::HashMap<String, i16>>,
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pub grid_row_line_names: Option<std::collections::HashMap<String, i16>>,
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/// Raw `grid-column`/`grid-row` value when it references a named line (so it
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/// cannot be resolved to a `taffy::Line` until the parent's line-name map is
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/// known). Resolved in the same later pass; numeric/`span` values still fill
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/// `grid_column`/`grid_row` directly at cascade time.
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pub grid_column_raw: Option<String>,
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pub grid_row_raw: Option<String>,
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pub column_gap: Option<f32>,
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pub row_gap: Option<f32>,
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/// `border-spacing: <horizontal> <vertical>?` (or the `cellspacing`
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/// attribute). Only meaningful on a `<table>`; taffy has no native table
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/// display mode, so `dom::propagate_border_spacing` distributes this down
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/// as the table's own row gap and each descendant `<tr>`'s column gap.
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pub border_spacing: Option<(f32, f32)>,
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// Positioning. `position: absolute|fixed` takes the box out of normal flow.
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pub position: Option<taffy::Position>,
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/// Distinguishes `fixed` from `absolute`; both map to taffy's absolute
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/// layout mode, but fixed boxes use the initial containing block.
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pub position_fixed: bool,
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pub inset: [Option<Dimension>; 4], // top, right, bottom, left
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/// `overflow`/-x/-y other than `visible`: clips this element's descendants
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/// to its border box during paint. This is what makes the ubiquitous
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/// "visually-hidden but accessible" pattern (a 1x1 absolutely-positioned,
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/// clipped box used for skip-links and screen-reader-only labels) actually
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/// invisible instead of painting its text wherever it lands.
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pub overflow_hidden: bool,
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/// `float: left|right`. True CSS float needs per-line reflow around the
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/// float's shape, which taffy's block/flex/grid modes do not do; see
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/// `dom::group_float_zone` for the bounded approximation this drives.
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pub float: Option<Float>,
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/// `visibility: hidden|visible`, own value. `None` means "inherit the
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/// ancestor's computed value" (visibility, unlike most box properties, is
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/// a real inherited CSS property). Resolved into `effectively_invisible`
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/// during `dom::layout_dom`'s inheritance pass.
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pub visibility_hidden: Option<bool>,
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/// `opacity`, own (non-inherited) value in 0.0-1.0. `None` means the
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/// default of 1.0.
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pub opacity: Option<f32>,
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/// `vertical-align` for a table cell's content. Cells effectively default
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/// to `middle` in browsers (the HTML UA sheet sets it on row groups and
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/// cells inherit it); obscura applies it as main-axis alignment of the
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/// cell's flex-column stand-in. `None` on non-cell elements.
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pub vertical_align: Option<VerticalAlign>,
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/// `z-index` on a positioned element. `None` is `auto` (tree order). A
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/// non-zero value lifts the element's whole subtree into a separate paint
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/// layer: negatives under the normal flow, positives above it, sorted.
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pub z_index: Option<i32>,
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/// `clear`, when set: this element moves below preceding floats on the
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/// given side(s), ending their float zone.
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pub clear: Option<Clear>,
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/// Resolved during the inheritance pass: true when this element should
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/// not be painted at all, either from its own or an inherited
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/// `visibility: hidden`, or because the product of its own and every
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/// ancestor's `opacity` has collapsed to (near) zero. Real `opacity`
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/// composites as translucent groups, which our paint step does not do;
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/// collapsing it to a binary paint/don't-paint decision is enough to
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/// make the extremely common "opacity:0 + visibility:hidden" collapsed
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/// dropdown/panel pattern actually invisible, without needing full alpha
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/// compositing.
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pub effectively_invisible: bool,
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/// Literal text injected by a `::before`/`::after` rule with a plain
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/// string-literal `content` (see `css::Stylesheet::pseudo_content`).
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/// Rendered as an extra word-run at the start/end of this element's
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/// children, same as if it were real text content.
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pub before_content: Option<String>,
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pub after_content: Option<String>,
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/// True for `inline-block`/`inline-flex`/`inline-grid`: participates in
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/// the surrounding inline flow from the outside, like plain `inline`
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/// (both currently collapse to `Display::Inline` — this engine has no
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/// separate inline-block layout mode), but unlike plain `inline` it must
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/// stay a single atomic box rather than have its own content merge into
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/// the parent's line-breaking. `dom::is_flattenable_inline` uses this to
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/// avoid flattening these away: doing so would lose the element as its
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/// own box (including any `::before`/`::after` content attached to it).
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pub is_inline_block: bool,
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/// `display: contents`: the element generates no box of its own; its
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/// children participate in the parent's formatting context directly
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/// (`dom::build_any` splices them into the parent's child list). Kept as a
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/// flag beside `display` because the element still carries inherited styles
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/// for its subtree and `display:none` must still win.
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pub display_contents: bool,
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/// `list-style-type` (or the `list-style` shorthand). Inherited, like in
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/// real CSS; `None` means "not set on this element, inherit". Resolved to
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/// a concrete value during the inheritance pass. Only `<li>` elements draw
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/// a marker from it, but it is carried on every element because it
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/// inherits (a `list-style: none` on a `<ul>` must reach its `<li>`
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/// children, which is how nav menus suppress bullets).
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pub list_style: Option<ListStyle>,
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/// `line-height`. Inherited. `None` means "not set, inherit"; resolved to
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/// a concrete value in the inheritance pass. Drives the vertical rhythm of
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/// shaped text (a fixed ratio made real-site prose noticeably tighter than
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/// Chromium).
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pub line_height: Option<LineHeight>,
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/// `text-transform`. Inherited. Applied to span text before shaping.
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pub text_transform: Option<TextTransform>,
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/// `text-decoration-line: underline` (or the `text-decoration` shorthand).
|
|
/// Not inherited in CSS, but a decoration visually covers descendant inline
|
|
/// text, so it is propagated into the shaped spans of the element's subtree
|
|
/// (this is what underlines links, which are underlined by UA default).
|
|
pub underline: Option<bool>,
|
|
|
|
/// `font-style: italic|oblique`. Inherited. Selects the oblique face when
|
|
/// shaping (we embed the DejaVu Sans oblique/bold-oblique faces). `None`
|
|
/// means inherit.
|
|
pub font_style_italic: Option<bool>,
|
|
|
|
/// `object-fit` for a replaced element (`<img>`). Controls how the decoded
|
|
/// image is scaled into the element's box when their aspect ratios differ;
|
|
/// `Fill` (default) stretches to the box, the rest preserve aspect ratio.
|
|
/// Only consulted in the image paint path.
|
|
pub object_fit: ObjectFit,
|
|
/// `transform: translate(x[, y])` / `translateX` / `translateY`, stored
|
|
/// unresolved as (dx, dy). Applied at paint time as an offset to the
|
|
/// element's own box AND its whole descendant subtree; percentages resolve
|
|
/// against the element's own border-box size then. This is what makes the
|
|
/// canonical `translate(-50%,-50%)` centering of an absolutely-positioned
|
|
/// box land in the right place, and moves a `translate(-9999px,0)`
|
|
/// off-screen skip-link out of view instead of painting it on-screen. Not
|
|
/// inherited (transform is a non-inherited property).
|
|
pub transform_translate: Option<(Dimension, Dimension)>,
|
|
/// Independent CSS-property triggers that establish containing blocks for
|
|
/// absolute and fixed descendants. Kept as a bitset so `filter:none`
|
|
/// cannot clear a transform/containment trigger from another property.
|
|
pub containing_block_triggers: u16,
|
|
/// `transform: scale(sx[, sy])` / `scaleX` / `scaleY`, captured as (sx, sy).
|
|
/// Parsed and stored so a value that mixes scale with translate still yields
|
|
/// its translate part; scale is not yet folded into paint geometry (doing so
|
|
/// correctly would require scaling every descendant's size and text, outside
|
|
/// the paint-time translate-offset model used here).
|
|
pub transform_scale: Option<(f32, f32)>,
|
|
/// `box-shadow` (first layer only). Painted behind the element's own
|
|
/// background/border box: cards, buttons, menus, and modals across the
|
|
/// modern web rely on it for depth, and without it those elements paint
|
|
/// flat. See [`BoxShadow`] and `paint::paint_box_shadow`.
|
|
pub box_shadow: Option<BoxShadow>,
|
|
}
|
|
|
|
pub(crate) const CB_TRIGGER_TRANSFORM: u16 = 1 << 0;
|
|
pub(crate) const CB_TRIGGER_FILTER: u16 = 1 << 1;
|
|
pub(crate) const CB_TRIGGER_BACKDROP_FILTER: u16 = 1 << 2;
|
|
pub(crate) const CB_TRIGGER_PERSPECTIVE: u16 = 1 << 3;
|
|
pub(crate) const CB_TRIGGER_CONTAIN: u16 = 1 << 4;
|
|
pub(crate) const CB_TRIGGER_WILL_CHANGE: u16 = 1 << 5;
|
|
pub(crate) const CB_TRIGGER_CONTENT_VISIBILITY: u16 = 1 << 6;
|
|
|
|
impl LayoutStyle {
|
|
pub(crate) fn establishes_positioning_containing_block(&self) -> bool {
|
|
self.containing_block_triggers != 0
|
|
}
|
|
}
|
|
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
|
pub enum Float {
|
|
Left,
|
|
Right,
|
|
}
|
|
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
|
|
pub enum BoxSizing {
|
|
#[default]
|
|
ContentBox,
|
|
BorderBox,
|
|
/// A specified CSS-wide `inherit` value. The DOM's top-down computed-style
|
|
/// pass resolves this to the parent's computed value before layout.
|
|
Inherit,
|
|
}
|
|
|
|
/// One `box-shadow` layer. Offsets, blur, and spread are in CSS px; `color` is
|
|
/// the resolved RGBA (falling back to the element's text color, per CSS
|
|
/// `currentColor`, when the value omits a color); `inset` distinguishes an
|
|
/// inner shadow from the default outer (drop) shadow. Only the first layer of a
|
|
/// comma-separated list is modeled.
|
|
#[derive(Debug, Clone, Copy, PartialEq)]
|
|
pub struct BoxShadow {
|
|
pub offset_x: f32,
|
|
pub offset_y: f32,
|
|
pub blur: f32,
|
|
pub spread: f32,
|
|
pub color: [u8; 4],
|
|
pub inset: bool,
|
|
}
|
|
|
|
/// `object-fit` for replaced elements (`<img>`): how the image's intrinsic
|
|
/// content is scaled into its box when their aspect ratios differ. `Fill` (the
|
|
/// default) stretches to the whole box; the others preserve the image's aspect
|
|
/// ratio, either letterboxing inside the box (`Contain`), cropping to cover it
|
|
/// (`Cover`), or using the intrinsic size (`None`, or `ScaleDown` which is
|
|
/// `Contain` capped at the intrinsic size so it never upscales).
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
|
|
pub enum ObjectFit {
|
|
#[default]
|
|
Fill,
|
|
Contain,
|
|
Cover,
|
|
ScaleDown,
|
|
None,
|
|
}
|
|
|
|
/// `vertical-align` positions for table-cell content. `baseline` (and the
|
|
/// text-level values like sub/super, which do not apply to cells) map to
|
|
/// `Top` as an approximation: real per-row baseline alignment needs shared
|
|
/// ascent metrics across the row.
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
|
pub enum VerticalAlign {
|
|
Top,
|
|
Middle,
|
|
Bottom,
|
|
}
|
|
|
|
/// `clear`: which floated side(s) an element moves below. Ends the float
|
|
/// zone in `dom::build_children_with_float_zone` (the clearfix idiom).
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
|
pub enum Clear {
|
|
Left,
|
|
Right,
|
|
Both,
|
|
}
|
|
|
|
/// `line-height`: `normal` (a font-relative default), a unitless multiple of
|
|
/// font-size, or an absolute pixel length.
|
|
#[derive(Debug, Clone, Copy, PartialEq)]
|
|
pub enum LineHeight {
|
|
Normal,
|
|
Ratio(f32),
|
|
Px(f32),
|
|
}
|
|
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
|
pub enum TextTransform {
|
|
None,
|
|
Uppercase,
|
|
Lowercase,
|
|
Capitalize,
|
|
}
|
|
|
|
/// `list-style-type` values we render a marker for. `Decimal` numbers the
|
|
/// item by its position among sibling list items.
|
|
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
|
|
pub enum ListStyle {
|
|
None,
|
|
Disc,
|
|
Circle,
|
|
Square,
|
|
Decimal,
|
|
}
|
|
|
|
/// A node in the input layout tree. `text` is carried for the paint phase; it
|
|
/// does not affect layout in phase 1 (inline/text layout comes later).
|
|
#[derive(Debug, Clone)]
|
|
pub struct LayoutNode {
|
|
pub style: LayoutStyle,
|
|
#[allow(dead_code)]
|
|
pub text: Option<String>,
|
|
pub children: Vec<LayoutNode>,
|
|
}
|
|
|
|
impl LayoutNode {
|
|
pub fn leaf(style: LayoutStyle) -> Self {
|
|
LayoutNode { style, text: None, children: Vec::new() }
|
|
}
|
|
}
|
|
|
|
/// Computed geometry for one node and its subtree.
|
|
#[derive(Debug, Clone, Default)]
|
|
pub struct NodeRect {
|
|
/// Border box, in viewport coordinates.
|
|
pub border_box: Rect,
|
|
pub children: Vec<NodeRect>,
|
|
}
|
|
|
|
/// Lay out `root` within a `viewport` (width, height) in CSS pixels and return
|
|
/// the border-box geometry per node, mirroring the input tree.
|
|
pub fn layout(root: &LayoutNode, viewport: (f32, f32)) -> NodeRect {
|
|
let mut tree: TaffyTree = TaffyTree::new();
|
|
let root_id = build_node(&mut tree, root);
|
|
let _ = tree.compute_layout(
|
|
root_id,
|
|
taffy::Size {
|
|
width: taffy::AvailableSpace::Definite(viewport.0),
|
|
height: taffy::AvailableSpace::Definite(viewport.1),
|
|
},
|
|
);
|
|
read_node(&tree, root_id)
|
|
}
|
|
|
|
fn build_node(tree: &mut TaffyTree, node: &LayoutNode) -> NodeId {
|
|
let style = to_taffy_style(&node.style);
|
|
if node.children.is_empty() {
|
|
tree.new_leaf(style).expect("taffy new_leaf")
|
|
} else {
|
|
let child_ids: Vec<NodeId> =
|
|
node.children.iter().map(|c| build_node(tree, c)).collect();
|
|
tree.new_with_children(style, &child_ids).expect("taffy new_with_children")
|
|
}
|
|
}
|
|
|
|
fn read_node(tree: &TaffyTree, id: NodeId) -> NodeRect {
|
|
let layout = tree.layout(id).expect("taffy layout");
|
|
NodeRect {
|
|
border_box: Rect {
|
|
x: layout.location.x,
|
|
y: layout.location.y,
|
|
width: layout.size.width,
|
|
height: layout.size.height,
|
|
},
|
|
children: tree
|
|
.children(id)
|
|
.unwrap_or_default()
|
|
.iter()
|
|
.map(|&cid| read_node(tree, cid))
|
|
.collect(),
|
|
}
|
|
}
|
|
|
|
pub(crate) fn to_taffy_style(style: &LayoutStyle) -> Style {
|
|
let mut s = Style::DEFAULT;
|
|
s.box_sizing = match style.box_sizing {
|
|
BoxSizing::ContentBox => taffy::BoxSizing::ContentBox,
|
|
BoxSizing::BorderBox => taffy::BoxSizing::BorderBox,
|
|
// Programmatic LayoutStyle users do not have a DOM inheritance pass;
|
|
// fall back to the property's CSS initial value in that case.
|
|
BoxSizing::Inherit => taffy::BoxSizing::ContentBox,
|
|
};
|
|
|
|
// A block box that wants non-default cross-axis alignment (from
|
|
// text-align: center/right, the only way our engine currently sets
|
|
// align_items on a block-level element) needs a flex column to have any
|
|
// effect at all: taffy's native block algorithm (used for plain
|
|
// Display::Block) has no align-items concept whatsoever, it only ever
|
|
// places block children at the start edge. Promote such boxes to a flex
|
|
// column, matching the same column-flex approximation already used for
|
|
// elements like <td> and <center>.
|
|
let promote_for_alignment = style.display == Display::Block
|
|
&& matches!(style.align_items, Some(taffy::AlignItems::CENTER) | Some(taffy::AlignItems::FLEX_END));
|
|
|
|
s.display = match style.display {
|
|
Display::Block if promote_for_alignment => taffy::style::Display::Flex,
|
|
Display::Block => taffy::style::Display::Block,
|
|
Display::Flex => taffy::style::Display::Flex,
|
|
Display::Grid => taffy::style::Display::Grid,
|
|
Display::Inline => taffy::style::Display::Flex,
|
|
Display::None => taffy::style::Display::None,
|
|
};
|
|
if promote_for_alignment {
|
|
s.flex_direction = taffy::FlexDirection::Column;
|
|
}
|
|
if let Some(fd) = style.flex_direction {
|
|
s.flex_direction = fd;
|
|
}
|
|
if let Some(fw) = style.flex_wrap {
|
|
s.flex_wrap = fw;
|
|
} else if style.display == Display::Inline {
|
|
s.flex_direction = taffy::FlexDirection::Row;
|
|
s.flex_wrap = taffy::FlexWrap::Wrap;
|
|
} else {
|
|
s.flex_wrap = taffy::FlexWrap::NoWrap;
|
|
}
|
|
s.size = taffy::Size {
|
|
width: dimension(style.width),
|
|
height: dimension(style.height),
|
|
};
|
|
// Tell taffy's own layout algorithm about `overflow: hidden`, not just our
|
|
// paint-time clip rects: per spec, a flex/grid item's automatic minimum
|
|
// size is content-based only when its overflow is `visible`, and `0`
|
|
// otherwise. Without this, an explicit `height: 0; overflow: hidden`
|
|
// element (the common collapsed-dropdown-panel pattern: hidden until a
|
|
// sibling checkbox is checked) still grows to fit its content, since
|
|
// taffy has no way to know it should not.
|
|
if style.overflow_hidden {
|
|
s.overflow = taffy::Point { x: taffy::style::Overflow::Hidden, y: taffy::style::Overflow::Hidden };
|
|
}
|
|
s.min_size = taffy::Size {
|
|
width: dimension(style.min_width),
|
|
height: dimension(style.min_height),
|
|
};
|
|
s.max_size = taffy::Size {
|
|
width: dimension(style.max_width),
|
|
height: dimension(style.max_height),
|
|
};
|
|
if let Some(ar) = style.aspect_ratio {
|
|
if ar.is_finite() && ar > 0.0 {
|
|
s.aspect_ratio = Some(ar);
|
|
}
|
|
}
|
|
if let Some(ai) = style.align_items {
|
|
s.align_items = Some(ai);
|
|
}
|
|
if let Some(jc) = style.justify_content {
|
|
s.justify_content = Some(jc);
|
|
}
|
|
if let Some(fg) = style.flex_grow {
|
|
s.flex_grow = fg;
|
|
}
|
|
if let Some(fs) = style.flex_shrink {
|
|
s.flex_shrink = fs;
|
|
}
|
|
if style.flex_basis != Dimension::Auto {
|
|
s.flex_basis = dimension(style.flex_basis);
|
|
}
|
|
|
|
// Grid container tracks and gaps. obscura expands `repeat()` itself during
|
|
// parsing, so every stored track is a single (non-repeated) `MinMax`; wrap
|
|
// each as a `GridTemplateComponent::Single` for taffy 0.12. The 0.7-era
|
|
// fr->Auto row workaround (which stopped `minmax(0,1fr)` image rows from
|
|
// collapsing to a sliver) is gone: taffy 0.12 treats an in-flow child's
|
|
// vertical available space as indefinite, so fr rows of an auto-height grid
|
|
// size to their content the way real CSS does.
|
|
if style.display == Display::Grid {
|
|
if !style.grid_template_columns.is_empty() {
|
|
s.grid_template_columns = style
|
|
.grid_template_columns
|
|
.iter()
|
|
.cloned()
|
|
.map(taffy::GridTemplateComponent::Single)
|
|
.collect();
|
|
}
|
|
if !style.grid_template_rows.is_empty() {
|
|
s.grid_template_rows = style
|
|
.grid_template_rows
|
|
.iter()
|
|
.cloned()
|
|
.map(taffy::GridTemplateComponent::Single)
|
|
.collect();
|
|
}
|
|
}
|
|
let cg = style.column_gap.unwrap_or(0.0);
|
|
let rg = style.row_gap.unwrap_or(0.0);
|
|
s.gap = taffy::Size {
|
|
width: taffy::style::LengthPercentage::length(cg),
|
|
height: taffy::style::LengthPercentage::length(rg),
|
|
};
|
|
|
|
// Grid item placement (resolved from grid-area names or explicit lines).
|
|
// `GridPlacement` is no longer `Copy` in taffy 0.12 (it can carry a named
|
|
// line), so clone out of the borrowed style.
|
|
if let Some(gc) = &style.grid_column {
|
|
s.grid_column = gc.clone();
|
|
}
|
|
if let Some(gr) = &style.grid_row {
|
|
s.grid_row = gr.clone();
|
|
}
|
|
|
|
// Positioning. Absolute/fixed take the box out of flow.
|
|
if let Some(pos) = style.position {
|
|
s.position = pos;
|
|
s.inset = taffy::Rect {
|
|
top: inset_lpa(style.inset[0]),
|
|
right: inset_lpa(style.inset[1]),
|
|
bottom: inset_lpa(style.inset[2]),
|
|
left: inset_lpa(style.inset[3]),
|
|
};
|
|
}
|
|
|
|
s.margin = rect_auto(style.margin, style.margin_auto);
|
|
s.padding = rect_lp(style.padding);
|
|
s.border = rect_lp(style.border);
|
|
s
|
|
}
|
|
|
|
fn inset_lpa(v: Option<Dimension>) -> taffy::style::LengthPercentageAuto {
|
|
match v {
|
|
Some(Dimension::Px(px)) => taffy::style::LengthPercentageAuto::length(px),
|
|
Some(Dimension::Percent(p)) => taffy::style::LengthPercentageAuto::percent(p),
|
|
// Relative units are resolved to Px before layout; unresolved leftovers
|
|
// and `auto`/absent both map to Auto.
|
|
_ => taffy::style::LengthPercentageAuto::auto(),
|
|
}
|
|
}
|
|
|
|
fn dimension(v: Dimension) -> taffy::style::Dimension {
|
|
match v {
|
|
Dimension::Px(px) => taffy::style::Dimension::length(px),
|
|
Dimension::Percent(p) => taffy::style::Dimension::percent(p),
|
|
Dimension::Auto => taffy::style::Dimension::auto(),
|
|
// Relative units are resolved to Px before layout; if one slips
|
|
// through unresolved, fall back to its raw magnitude (em/rem ~16px)
|
|
// rather than panicking.
|
|
Dimension::Em(v) | Dimension::Rem(v) => taffy::style::Dimension::length(v * 16.0),
|
|
Dimension::Vw(v) | Dimension::Vh(v) | Dimension::Vmin(v) | Dimension::Vmax(v) => taffy::style::Dimension::length(v),
|
|
}
|
|
}
|
|
|
|
fn rect_lp(e: Edges) -> taffy::Rect<taffy::style::LengthPercentage> {
|
|
taffy::Rect {
|
|
top: taffy::style::LengthPercentage::length(e.top),
|
|
right: taffy::style::LengthPercentage::length(e.right),
|
|
bottom: taffy::style::LengthPercentage::length(e.bottom),
|
|
left: taffy::style::LengthPercentage::length(e.left),
|
|
}
|
|
}
|
|
|
|
fn rect_auto(e: Edges, auto: [bool; 4]) -> taffy::Rect<taffy::style::LengthPercentageAuto> {
|
|
let side = |value, is_auto| {
|
|
if is_auto {
|
|
taffy::style::LengthPercentageAuto::auto()
|
|
} else {
|
|
taffy::style::LengthPercentageAuto::length(value)
|
|
}
|
|
};
|
|
taffy::Rect {
|
|
top: side(e.top, auto[0]),
|
|
right: side(e.right, auto[1]),
|
|
bottom: side(e.bottom, auto[2]),
|
|
left: side(e.left, auto[3]),
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
|
|
fn make_box(display: Display, w: f32, h: f32) -> LayoutStyle {
|
|
LayoutStyle { display, width: Dimension::Px(w), height: Dimension::Px(h), ..Default::default() }
|
|
}
|
|
|
|
#[test]
|
|
fn block_children_stack_vertically() {
|
|
// A 1000px-wide viewport, two fixed-size block children: they should
|
|
// stack top-to-bottom at the expected y offsets.
|
|
let root = LayoutNode {
|
|
style: make_box(Display::Block, 1000.0, 800.0),
|
|
text: None,
|
|
children: vec![
|
|
LayoutNode::leaf(make_box(Display::Block, 1000.0, 50.0)),
|
|
LayoutNode::leaf(make_box(Display::Block, 1000.0, 30.0)),
|
|
],
|
|
};
|
|
let out = layout(&root, (1000.0, 800.0));
|
|
assert_eq!(out.border_box.width, 1000.0);
|
|
assert_eq!(out.children.len(), 2);
|
|
assert_eq!(out.children[0].border_box.height, 50.0);
|
|
assert_eq!(out.children[1].border_box.height, 30.0);
|
|
// Second block begins where the first ended.
|
|
assert!(
|
|
(out.children[1].border_box.y - out.children[0].border_box.y).abs()
|
|
>= out.children[0].border_box.height - 0.01,
|
|
"blocks should stack: c0.y={} c1.y={}",
|
|
out.children[0].border_box.y,
|
|
out.children[1].border_box.y
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn block_auto_margins_absorb_horizontal_free_space() {
|
|
let centered = LayoutStyle {
|
|
display: Display::Block,
|
|
width: Dimension::Px(300.0),
|
|
height: Dimension::Px(40.0),
|
|
margin_auto: [false, true, false, true],
|
|
..Default::default()
|
|
};
|
|
let pushed_end = LayoutStyle {
|
|
display: Display::Block,
|
|
width: Dimension::Px(200.0),
|
|
height: Dimension::Px(40.0),
|
|
margin: Edges { right: 50.0, ..Default::default() },
|
|
margin_auto: [false, false, false, true],
|
|
..Default::default()
|
|
};
|
|
let root = LayoutNode {
|
|
style: make_box(Display::Block, 900.0, 200.0),
|
|
text: None,
|
|
children: vec![LayoutNode::leaf(centered), LayoutNode::leaf(pushed_end)],
|
|
};
|
|
let out = layout(&root, (900.0, 200.0));
|
|
assert!((out.children[0].border_box.x - 300.0).abs() < 0.01);
|
|
assert!((out.children[1].border_box.x - 650.0).abs() < 0.01);
|
|
}
|
|
|
|
#[test]
|
|
fn flex_row_lays_out_horizontally() {
|
|
let root = LayoutNode {
|
|
style: LayoutStyle { display: Display::Flex, width: Dimension::Px(600.0), height: Dimension::Px(100.0), ..Default::default() },
|
|
text: None,
|
|
children: vec![
|
|
LayoutNode::leaf(make_box(Display::Block, 200.0, 100.0)),
|
|
LayoutNode::leaf(make_box(Display::Block, 200.0, 100.0)),
|
|
],
|
|
};
|
|
let out = layout(&root, (600.0, 400.0));
|
|
assert_eq!(out.border_box.width, 600.0);
|
|
assert_eq!(out.children.len(), 2);
|
|
// In a row the second child is to the right of the first.
|
|
assert!(
|
|
out.children[1].border_box.x > out.children[0].border_box.x,
|
|
"flex row should place children horizontally: c0.x={} c1.x={}",
|
|
out.children[0].border_box.x,
|
|
out.children[1].border_box.x
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn padding_expands_content_box_but_not_border_box() {
|
|
let content_box = LayoutNode {
|
|
style: LayoutStyle {
|
|
display: Display::Block,
|
|
width: Dimension::Px(100.0),
|
|
height: Dimension::Px(100.0),
|
|
padding: Edges { top: 10.0, right: 10.0, bottom: 10.0, left: 10.0 },
|
|
..Default::default()
|
|
},
|
|
text: None,
|
|
children: vec![],
|
|
};
|
|
let content_out = layout(&content_box, (1000.0, 800.0));
|
|
assert_eq!(content_out.border_box.width, 120.0);
|
|
|
|
let mut border_box = content_box;
|
|
border_box.style.box_sizing = BoxSizing::BorderBox;
|
|
let border_out = layout(&border_box, (1000.0, 800.0));
|
|
assert_eq!(border_out.border_box.width, 100.0);
|
|
}
|
|
}
|