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66edef8065
Instead of duplicating some of `NonReplacedContents` in `Contents`, divide it into either replaced and non-replaced content, since this is how the layout system processes `Contents` always. In addition, stop using `TryInto` to match replaced or non-replaced contents, as it is quite confusing to handle an `Err` as a success case.
443 lines
19 KiB
Rust
443 lines
19 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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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::{
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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, Overflow};
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use style_traits::CSSPixel;
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use webrender_traits::display_list::ScrollSensitivity;
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use crate::cell::ArcRefCell;
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use crate::context::LayoutContext;
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use crate::dom::{LayoutBox, NodeExt};
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use crate::dom_traversal::{iter_child_nodes, Contents, NodeAndStyleInfo, NonReplacedContents};
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use crate::flexbox::FlexLevelBox;
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use crate::flow::float::FloatBox;
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use crate::flow::inline::InlineItem;
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use crate::flow::{BlockContainer, BlockFormattingContext, BlockLevelBox};
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use crate::formatting_contexts::IndependentFormattingContext;
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use crate::fragment_tree::FragmentTree;
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use crate::geom::{LogicalVec2, PhysicalPoint, PhysicalRect, PhysicalSize};
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use crate::positioned::{AbsolutelyPositionedBox, PositioningContext};
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use crate::replaced::ReplacedContent;
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use crate::style_ext::{ComputedValuesExt, Display, DisplayGeneratingBox, DisplayInside};
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use crate::DefiniteContainingBlock;
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#[derive(Serialize)]
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pub struct BoxTree {
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/// Contains typically exactly one block-level box, which was generated by the root element.
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/// There may be zero if that element has `display: none`.
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root: BlockFormattingContext,
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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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pub fn construct<'dom, Node>(context: &LayoutContext, root_element: Node) -> Self
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where
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Node: 'dom + Copy + LayoutNode<'dom> + Send + Sync,
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{
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let boxes = construct_for_root_element(context, root_element);
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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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root: BlockFormattingContext {
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contents,
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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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/// This method attempts to incrementally update the box tree from an
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/// arbitrary node that is not necessarily the document's root element.
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///
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/// If the node is not a valid candidate for incremental update, the method
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/// loops over its parent. The only valid candidates for now are absolutely
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/// positioned boxes which don't change their outside display mode (i.e. it
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/// will not attempt to update from an absolutely positioned inline element
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/// which became an absolutely positioned block element). The value `true`
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/// is returned if an incremental update could be done, and `false`
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/// otherwise.
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///
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/// There are various pain points that need to be taken care of to extend
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/// the set of valid candidates:
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/// * it is not obvious how to incrementally check whether a block
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/// formatting context still contains floats or not;
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/// * the propagation of text decorations towards node descendants is
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/// hard to do incrementally with our current representation of boxes
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/// * how intrinsic content sizes are computed eagerly makes it hard
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/// to update those sizes for ancestors of the node from which we
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/// made an incremental update.
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pub fn update<'dom, Node>(context: &LayoutContext, mut dirty_node: Node) -> bool
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where
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Node: 'dom + Copy + LayoutNode<'dom> + Send + Sync,
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{
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#[allow(clippy::enum_variant_names)]
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enum UpdatePoint {
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AbsolutelyPositionedBlockLevelBox(ArcRefCell<BlockLevelBox>),
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AbsolutelyPositionedInlineLevelBox(ArcRefCell<InlineItem>),
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AbsolutelyPositionedFlexLevelBox(ArcRefCell<FlexLevelBox>),
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}
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fn update_point<'dom, Node>(
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node: Node,
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) -> Option<(Arc<ComputedValues>, DisplayInside, UpdatePoint)>
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where
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Node: NodeExt<'dom>,
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{
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if !node.is_element() {
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return None;
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}
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if node.type_id() == LayoutNodeType::Element(LayoutElementType::HTMLBodyElement) {
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// This can require changes to the canvas background.
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return None;
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}
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// Don't update unstyled nodes or nodes that have pseudo-elements.
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let element_data = node.style_data()?.element_data.borrow();
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if !element_data.styles.pseudos.is_empty() {
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return None;
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}
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let layout_data = node.layout_data()?;
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if layout_data.pseudo_before_box.borrow().is_some() {
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return None;
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}
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if layout_data.pseudo_after_box.borrow().is_some() {
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return None;
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}
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let primary_style = element_data.styles.primary();
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let box_style = primary_style.get_box();
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if !box_style.position.is_absolutely_positioned() {
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return None;
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}
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let display_inside = match Display::from(box_style.display) {
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Display::GeneratingBox(DisplayGeneratingBox::OutsideInside { inside, .. }) => {
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inside
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},
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_ => return None,
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};
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let update_point =
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match &*AtomicRef::filter_map(layout_data.self_box.borrow(), Option::as_ref)? {
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LayoutBox::DisplayContents => return None,
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LayoutBox::BlockLevel(block_level_box) => match &*block_level_box.borrow() {
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BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(_)
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if box_style.position.is_absolutely_positioned() =>
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{
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UpdatePoint::AbsolutelyPositionedBlockLevelBox(block_level_box.clone())
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},
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_ => return None,
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},
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LayoutBox::InlineBox(_) => return None,
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LayoutBox::InlineLevel(inline_level_box) => match &*inline_level_box.borrow() {
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InlineItem::OutOfFlowAbsolutelyPositionedBox(_)
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if box_style.position.is_absolutely_positioned() =>
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{
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UpdatePoint::AbsolutelyPositionedInlineLevelBox(
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inline_level_box.clone(),
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)
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},
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_ => return None,
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},
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LayoutBox::FlexLevel(flex_level_box) => match &*flex_level_box.borrow() {
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FlexLevelBox::OutOfFlowAbsolutelyPositionedBox(_)
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if box_style.position.is_absolutely_positioned() =>
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{
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UpdatePoint::AbsolutelyPositionedFlexLevelBox(flex_level_box.clone())
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},
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_ => return None,
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},
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};
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Some((primary_style.clone(), display_inside, update_point))
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}
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loop {
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if let Some((primary_style, display_inside, update_point)) = update_point(dirty_node) {
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let contents = ReplacedContent::for_element(dirty_node, context)
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.map_or_else(|| NonReplacedContents::OfElement.into(), Contents::Replaced);
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let info = NodeAndStyleInfo::new(dirty_node, Arc::clone(&primary_style));
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let out_of_flow_absolutely_positioned_box = ArcRefCell::new(
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AbsolutelyPositionedBox::construct(context, &info, display_inside, contents),
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);
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match update_point {
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UpdatePoint::AbsolutelyPositionedBlockLevelBox(block_level_box) => {
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*block_level_box.borrow_mut() =
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BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(
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out_of_flow_absolutely_positioned_box,
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);
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},
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UpdatePoint::AbsolutelyPositionedInlineLevelBox(inline_level_box) => {
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*inline_level_box.borrow_mut() =
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InlineItem::OutOfFlowAbsolutelyPositionedBox(
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out_of_flow_absolutely_positioned_box,
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);
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},
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UpdatePoint::AbsolutelyPositionedFlexLevelBox(flex_level_box) => {
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*flex_level_box.borrow_mut() =
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FlexLevelBox::OutOfFlowAbsolutelyPositionedBox(
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out_of_flow_absolutely_positioned_box,
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);
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},
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}
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return true;
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}
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dirty_node = match dirty_node.parent_node() {
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Some(parent) => parent,
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None => return false,
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};
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}
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}
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}
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fn construct_for_root_element<'dom>(
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context: &LayoutContext,
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root_element: impl NodeExt<'dom>,
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) -> Vec<ArcRefCell<BlockLevelBox>> {
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let info = NodeAndStyleInfo::new(root_element, root_element.style(context));
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let box_style = info.style.get_box();
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let display_inside = match Display::from(box_style.display) {
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Display::None => {
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root_element.unset_all_boxes();
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return Vec::new();
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},
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Display::Contents => {
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// Unreachable because the style crate adjusts the computed values:
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// https://drafts.csswg.org/css-display-3/#transformations
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// “'display' of 'contents' computes to 'block' on the root element”
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unreachable!()
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},
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// The root element is blockified, ignore DisplayOutside
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Display::GeneratingBox(display_generating_box) => display_generating_box.display_inside(),
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};
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let contents = ReplacedContent::for_element(root_element, context)
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.map_or_else(|| NonReplacedContents::OfElement.into(), Contents::Replaced);
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let root_box = if box_style.position.is_absolutely_positioned() {
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BlockLevelBox::OutOfFlowAbsolutelyPositionedBox(ArcRefCell::new(
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AbsolutelyPositionedBox::construct(context, &info, display_inside, contents),
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))
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} else if box_style.float.is_floating() {
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BlockLevelBox::OutOfFlowFloatBox(FloatBox::construct(
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context,
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&info,
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display_inside,
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contents,
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))
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} else {
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let propagated_text_decoration_line = info.style.clone_text_decoration_line();
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BlockLevelBox::Independent(IndependentFormattingContext::construct(
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context,
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&info,
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display_inside,
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contents,
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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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.set(LayoutBox::BlockLevel(root_box.clone()));
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vec![root_box]
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}
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impl BoxTree {
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pub fn layout(
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&self,
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layout_context: &LayoutContext,
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viewport: euclid::Size2D<f32, CSSPixel>,
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) -> FragmentTree {
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let style = ComputedValues::initial_values();
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// FIXME: use the document’s mode:
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// https://drafts.csswg.org/css-writing-modes/#principal-flow
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let physical_containing_block = PhysicalRect::new(
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PhysicalPoint::zero(),
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PhysicalSize::new(Length::new(viewport.width), Length::new(viewport.height)),
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);
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let initial_containing_block = DefiniteContainingBlock {
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size: LogicalVec2 {
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inline: physical_containing_block.size.width.into(),
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block: physical_containing_block.size.height.into(),
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},
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style,
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};
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let mut positioning_context =
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PositioningContext::new_for_containing_block_for_all_descendants();
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let independent_layout = self.root.layout(
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layout_context,
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&mut positioning_context,
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&(&initial_containing_block).into(),
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);
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let mut root_fragments = independent_layout
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.fragments
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.into_iter()
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.map(ArcRefCell::new)
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.collect::<Vec<_>>();
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// Zero box for `:root { display: none }`, one for the root element otherwise.
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assert!(root_fragments.len() <= 1);
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// There may be more fragments at the top-level
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// (for positioned boxes whose containing is the initial containing block)
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// but only if there was one fragment for the root element.
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positioning_context.layout_initial_containing_block_children(
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layout_context,
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&initial_containing_block,
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&mut root_fragments,
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);
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let scrollable_overflow = root_fragments
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.iter()
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.fold(PhysicalRect::zero(), |acc, child| {
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let child_overflow = child
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.borrow()
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.scrollable_overflow(&physical_containing_block);
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// https://drafts.csswg.org/css-overflow/#scrolling-direction
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// We want to clip scrollable overflow on box-start and inline-start
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// sides of the scroll container.
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//
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// FIXME(mrobinson, bug 25564): This should take into account writing
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// mode.
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let child_overflow = PhysicalRect::new(
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euclid::Point2D::zero(),
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euclid::Size2D::new(
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child_overflow.size.width + child_overflow.origin.x,
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child_overflow.size.height + child_overflow.origin.y,
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),
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);
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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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/// <https://drafts.csswg.org/css-backgrounds/#root-background>
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#[derive(Clone, Serialize)]
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pub struct CanvasBackground {
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/// DOM node for the root element
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pub root_element: OpaqueNode,
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/// The element whose style the canvas takes background properties from (see next field).
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/// This can be the root element (same as the previous field), or the HTML `<body>` element.
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/// See <https://drafts.csswg.org/css-backgrounds/#body-background>
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pub from_element: OpaqueNode,
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/// The computed styles to take background properties from.
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#[serde(skip)]
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pub style: Option<Arc<ComputedValues>>,
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}
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impl CanvasBackground {
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fn for_root_element<'dom>(context: &LayoutContext, root_element: impl NodeExt<'dom>) -> Self {
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let root_style = root_element.style(context);
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let mut style = root_style;
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let mut from_element = root_element;
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// https://drafts.csswg.org/css-backgrounds/#body-background
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// “if the computed value of background-image on the root element is none
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// and its background-color is transparent”
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if style.background_is_transparent() &&
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// “For documents whose root element is an HTML `HTML` element
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// or an XHTML `html` element”
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root_element.type_id() == LayoutNodeType::Element(LayoutElementType::HTMLHtmlElement) &&
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// Don’t try to access styles for an unstyled subtree
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!matches!(style.clone_display().into(), Display::None)
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{
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// “that element’s first HTML `BODY` or XHTML `body` child element”
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if let Some(body) = iter_child_nodes(root_element).find(|child| {
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child.is_element() &&
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child.type_id() ==
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LayoutNodeType::Element(LayoutElementType::HTMLBodyElement)
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}) {
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style = body.style(context);
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from_element = body;
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}
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}
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Self {
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root_element: root_element.opaque(),
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from_element: from_element.opaque(),
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// “However, if no boxes are generated for the element
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// whose background would be used for the canvas
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// (for example, if the root element has display: none),
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// then the canvas background is transparent.”
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style: if let Display::GeneratingBox(_) = style.clone_display().into() {
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Some(style)
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} else {
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None
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},
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}
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}
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}
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