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e7019f2721
Instead of producing a tree of stacking contexts, display list
generation now produces a flat list of display items and a tree of
stacking contexts. This will eventually allow display list construction
to produce and modify WebRender vertex buffers directly, removing the
overhead of display list conversion. This change also moves
layerization of the display list to the paint thread, since it isn't
currently useful for WebRender.
To accomplish this, display list generation now takes three passes of
the flow tree:
1. Calculation of absolute positions.
2. Collection of a tree of stacking contexts.
3. Creation of a list of display items.
After collection of display items, they are sorted based upon the index
of their parent stacking contexts and their position in CSS 2.1
Appendeix E stacking order.
This is a big change, but it actually simplifies display list generation.
65 lines
1.8 KiB
Rust
65 lines
1.8 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 http://mozilla.org/MPL/2.0/. */
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/// A struct that makes it easier to print out a pretty tree of data, which
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/// can be visually scanned more easily.
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pub struct PrintTree {
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/// The current level of recursion.
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level: u32,
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/// An item which is queued up, so that we can determine if we need
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/// a mid-tree prefix or a branch ending prefix.
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queued_item: Option<String>,
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}
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impl PrintTree {
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pub fn new(title: String) -> PrintTree {
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println!("┌ {}", title);
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PrintTree {
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level: 1,
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queued_item: None,
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}
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}
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/// Descend one level in the tree with the given title.
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pub fn new_level(&mut self, title: String) {
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self.flush_queued_item("├─");
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self.print_level_prefix();
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println!("├─ {}", title);
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self.level = self.level + 1;
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}
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/// Ascend one level in the tree.
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pub fn end_level(&mut self) {
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self.flush_queued_item("└─");
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self.level = self.level - 1;
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}
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/// Add an item to the current level in the tree.
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pub fn add_item(&mut self, text: String) {
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self.flush_queued_item("├─");
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self.queued_item = Some(text);
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}
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fn print_level_prefix(&self) {
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for _ in 0..self.level {
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print!("│ ");
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}
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}
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fn flush_queued_item(&mut self, prefix: &str) {
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if let Some(queued_item) = self.queued_item.take() {
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self.print_level_prefix();
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println!("{} {}", prefix, queued_item);
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}
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}
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}
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impl Drop for PrintTree {
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fn drop(&mut self) {
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self.flush_queued_item("└─");
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}
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}
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