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Implement basic overflow computation. Closes #1148.

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This adds just 4 ms out of ~120 ms on the rainbow page.
This commit is contained in:
Patrick Walton 2013-10-29 19:19:51 -07:00
parent cc76a2188e
commit 5327c9c44f
5 changed files with 65 additions and 20 deletions
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46
src/components/main/layout/layout_task.rs
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@ -138,15 +138,16 @@ impl<'self> PreorderFlowTraversal for AssignWidthsTraversal<'self> {
}
}
/// The assign-heights traversal, the last (and most expensive) part of layout computation.
/// Determines the final heights for all layout objects. In Gecko this corresponds to
/// `FinishAndStoreOverflow`.
struct AssignHeightsTraversal<'self>(&'self mut LayoutContext);
/// The assign-heights-and-store-overflow traversal, the last (and most expensive) part of layout
/// computation. Determines the final heights for all layout objects, computes positions, and
/// computes overflow regions. In Gecko this corresponds to `FinishAndStoreOverflow`.
struct AssignHeightsAndStoreOverflowTraversal<'self>(&'self mut LayoutContext);
impl<'self> PostorderFlowTraversal for AssignHeightsTraversal<'self> {
impl<'self> PostorderFlowTraversal for AssignHeightsAndStoreOverflowTraversal<'self> {
#[inline]
fn process(&mut self, flow: &mut FlowContext) -> bool {
flow.assign_height(**self);
flow.store_overflow(**self);
true
}
@ -296,6 +297,29 @@ impl LayoutTask {
self.stylist.add_stylesheet(sheet, AuthorOrigin);
}
/// Performs layout constraint solving.
///
/// This corresponds to `Reflow()` in Gecko and `layout()` in WebKit/Blink and should be
/// benchmarked against those two. It is marked `#[inline(never)]` to aid profiling.
#[inline(never)]
fn solve_constraints(&mut self,
layout_root: &mut FlowContext,
layout_context: &mut LayoutContext) {
let _ = layout_root.traverse_postorder(&mut BubbleWidthsTraversal(layout_context));
// FIXME(kmc): We want to do
// for flow in layout_root.traverse_preorder_prune(|f|
// f.restyle_damage().lacks(Reflow))
// but FloatContext values can't be reused, so we need to recompute them every time.
// NOTE: this currently computes borders, so any pruning should separate that operation out.
let _ = layout_root.traverse_preorder(&mut AssignWidthsTraversal(layout_context));
// For now, this is an inorder traversal
// FIXME: prune this traversal as well
let _ = layout_root.traverse_postorder(&mut
AssignHeightsAndStoreOverflowTraversal(layout_context));
}
/// The high-level routine that performs layout tasks.
fn handle_reflow(&mut self, data: &Reflow) {
// FIXME: Isolate this transmutation into a "bridge" module.
@ -365,17 +389,7 @@ impl LayoutTask {
// Perform the primary layout passes over the flow tree to compute the locations of all
// the boxes.
do profile(time::LayoutMainCategory, self.profiler_chan.clone()) {
let _ = layout_root.traverse_postorder(&mut BubbleWidthsTraversal(&mut layout_ctx));
// FIXME(kmc): We want to do
// for flow in layout_root.traverse_preorder_prune(|f| f.restyle_damage().lacks(Reflow))
// but FloatContext values can't be reused, so we need to recompute them every time.
// NOTE: this currently computes borders, so any pruning should separate that operation out.
let _ = layout_root.traverse_preorder(&mut AssignWidthsTraversal(&mut layout_ctx));
// For now, this is an inorder traversal
// FIXME: prune this traversal as well
let _ = layout_root.traverse_postorder(&mut AssignHeightsTraversal(&mut layout_ctx));
self.solve_constraints(layout_root, &mut layout_ctx)
}
// Build the display list if necessary, and send it to the renderer.