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layout: Propagate overflow values from <body>
to root element (#31618)
The specification gives instructions for how these values should be propagated. The other big changs here is that they aren't applied to the `<body>`. Co-authored-by: Oriol Brufau <obrufau@igalia.com>
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03d64d0675
commit
716f4a006d
17 changed files with 82 additions and 27 deletions
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@ -3,14 +3,17 @@
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use atomic_refcell::AtomicRef;
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use script_layout_interface::wrapper_traits::LayoutNode;
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use script_layout_interface::wrapper_traits::{
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LayoutNode, ThreadSafeLayoutElement, ThreadSafeLayoutNode,
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};
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use script_layout_interface::{LayoutElementType, LayoutNodeType};
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use serde::Serialize;
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use servo_arc::Arc;
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use style::dom::OpaqueNode;
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use style::properties::ComputedValues;
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use style::values::computed::Length;
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use style::values::computed::{Length, Overflow};
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use style_traits::CSSPixel;
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use webrender_api::ScrollSensitivity;
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use crate::cell::ArcRefCell;
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use crate::context::LayoutContext;
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@ -36,6 +39,9 @@ pub struct BoxTree {
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/// <https://drafts.csswg.org/css-backgrounds/#special-backgrounds>
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canvas_background: CanvasBackground,
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/// Whether or not the root element should be sensitive to scrolling input events.
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sensitive_to_scroll_input: bool,
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}
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impl BoxTree {
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@ -48,6 +54,35 @@ impl BoxTree {
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// Zero box for `:root { display: none }`, one for the root element otherwise.
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assert!(boxes.len() <= 1);
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// From https://drafts.csswg.org/css-overflow/#propdef-overflow:
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// > UAs must apply the overflow-* values set on the root element to the viewport when the
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// > root element’s display value is not none. However, when the root element is an [HTML]
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// > html element (including XML syntax for HTML) whose overflow value is visible (in both
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// > axes), and that element has as a child a body element whose display value is also not
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// > none, user agents must instead apply the overflow-* values of the first such child
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// > element to the viewport. The element from which the value is propagated must then have a
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// > used overflow value of visible.
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//
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// TODO: This should handle when different overflow is set multiple axes, which requires the
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// compositor scroll tree to allow setting a value per axis.
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let root_style = root_element.style(context);
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let mut root_overflow = root_style.get_box().overflow_y;
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if root_overflow == Overflow::Visible && !root_style.get_box().display.is_none() {
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for child in iter_child_nodes(root_element) {
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if !child.to_threadsafe().as_element().map_or(false, |element| {
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element.is_body_element_of_html_element_root()
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}) {
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continue;
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}
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let style = child.style(context);
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if !style.get_box().display.is_none() {
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root_overflow = style.get_box().overflow_y;
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break;
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}
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}
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}
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let contents = BlockContainer::BlockLevelBoxes(boxes);
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let contains_floats = contents.contains_floats();
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Self {
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@ -56,6 +91,7 @@ impl BoxTree {
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contains_floats,
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},
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canvas_background: CanvasBackground::for_root_element(context, root_element),
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sensitive_to_scroll_input: root_overflow != Overflow::Hidden,
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}
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}
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@ -252,6 +288,7 @@ fn construct_for_root_element<'dom>(
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propagated_text_decoration_line,
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))
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};
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let root_box = ArcRefCell::new(root_box);
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root_element
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.element_box_slot()
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@ -330,11 +367,18 @@ impl BoxTree {
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acc.union(&child_overflow)
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});
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let root_scroll_sensitivity = if self.sensitive_to_scroll_input {
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ScrollSensitivity::ScriptAndInputEvents
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} else {
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ScrollSensitivity::Script
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};
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FragmentTree {
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root_fragments,
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scrollable_overflow,
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initial_containing_block: physical_containing_block,
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canvas_background: self.canvas_background.clone(),
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root_scroll_sensitivity,
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}
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}
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}
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