render: size and paint native selects

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SGavrl committed 2026-07-26 22:11:39 +00:00
1 parent 9c71700824
commit 35c54936d5
3 files changed
+209 -3

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+86 -3
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@@ -1090,15 +1090,79 @@ pub(crate) fn layout_dom_with_web_fonts(
// top-down values are known.
propagate_border_spacing(tree, &mut styles);
// Resolve native input-control intrinsic border-box geometry after
// Resolve native form-control intrinsic border-box geometry after
// inheritance and author cascading. Text-like inputs use the HTML
// `size` attribute (20 by default) and the control's own computed
// font; author CSS widths/heights remain authoritative. Without this
// replaced-control sizing, every input is an empty auto-sized leaf
// (0px tall and often stretched to its container).
// replaced-control sizing, inputs/selects are empty auto-sized leaves
// (0px tall and often stretched to their container).
for (&id, style) in styles.iter_mut() {
let Some(node) = tree.get_node(id) else { continue };
let Some(element) = node.as_element() else { continue };
if element.local.as_ref() == "select" {
let option_labels: Vec<String> = tree
.descendants(id)
.into_iter()
.filter(|option_id| {
tree.get_node(*option_id)
.map_or(false, |option| {
option
.as_element()
.map_or(false, |name| name.local.as_ref() == "option")
})
})
.map(|option_id| tree.text_content(option_id).trim().to_string())
.collect();
let font_size = style.font_size.unwrap_or(13.333_333).max(1.0);
let bold = crate::style::used_font_weight(style) >= 600;
let label_width = option_labels
.iter()
.map(|label| {
text_width(
label,
font_size,
bold,
style.font_family.as_deref(),
)
})
.fold(0.0f32, f32::max);
let horizontal_edges = style.padding.left
+ style.padding.right
+ style.border.left
+ style.border.right;
let vertical_edges = style.padding.top
+ style.padding.bottom
+ style.border.top
+ style.border.bottom;
let rows = node
.get_attribute("size")
.and_then(|value| value.parse::<usize>().ok())
.filter(|&value| value > 1)
.unwrap_or(1) as f32;
let intrinsic_width = label_width + horizontal_edges;
let intrinsic_height =
crate::inline::used_line_height(style).max(1.0) * rows
+ vertical_edges;
if style.width == crate::Dimension::Auto {
style.width = crate::Dimension::Px(
if style.box_sizing == crate::BoxSizing::ContentBox {
label_width
} else {
intrinsic_width
},
);
}
if style.height == crate::Dimension::Auto {
style.height = crate::Dimension::Px(
if style.box_sizing == crate::BoxSizing::ContentBox {
(intrinsic_height - vertical_edges).max(0.0)
} else {
intrinsic_height
},
);
}
continue;
}
if element.local.as_ref() != "input" {
continue;
}
@@ -5095,4 +5159,23 @@ mod tests {
assert_eq!(pseudo.line_height, host.line_height);
}
#[test]
fn native_select_sizes_for_its_widest_option() {
let tree = parse_html(
r#"<select id="language">
<option selected>En</option>
<option>Brazilian Portuguese</option>
</select>"#,
);
let laid = layout_dom(&tree, (500.0, 200.0));
let select = tree.get_element_by_id("language").unwrap();
let rect = laid.rects[&select];
assert!(rect.width > 120.0, "widest option should set width: {rect:?}");
assert!(
(18.0..=22.0).contains(&rect.height),
"closed native select should have one-line control height: {rect:?}"
);
}
}
+99
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@@ -469,6 +469,52 @@ pub fn paint_dom(tree: &DomTree, viewport: (f32, f32), base_url: Option<&str>) -
}
}
// 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(),
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
@@ -677,6 +723,33 @@ fn list_marker_text(tree: &DomTree, nid: obscura_dom::tree::NodeId, style: Optio
}
}
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>> {
@@ -3092,6 +3165,32 @@ mod tests {
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
+24
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@@ -115,6 +115,30 @@ pub fn ua_style(tag: &str) -> LayoutStyle {
style.display = Display::Inline;
style.is_inline_block = true;
style.text_align = Some(taffy::AlignItems::CENTER);
} else if tag == "select" {
// A closed native select is an atomic inline control. Its option
// children belong to the popup (and remain display:none in our frame
// tree); the select itself gets intrinsic geometry and paints the
// selected label.
style.display = Display::Inline;
style.is_inline_block = true;
style.font_size = Some(13.333_333);
style.font_family = Some("arial".to_string());
style.line_height = Some(crate::LineHeight::Normal);
style.padding = Edges {
top: 1.0,
right: 20.0,
bottom: 1.0,
left: 2.0,
};
style.border = Edges {
top: 1.0,
right: 1.0,
bottom: 1.0,
left: 1.0,
};
style.border_color = Some([118, 118, 118, 255]);
style.background_color = Some([255, 255, 255, 255]);
} else if tag == "input" {
// Native text controls are atomic inline-level boxes with their own
// platform font and intrinsic border-box dimensions; they do not