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Clip display list based on frame viewport
Instead of creating a display list for the entire page, only create one for an area that expands around the viewport. On my machine this makes incremental layout of http://timecube.com 50% faster.
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f4471f0602
commit
c7327450ef
11 changed files with 130 additions and 34 deletions
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@ -19,19 +19,21 @@ use layout_interface::{
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};
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use script_traits::{UntrustedNodeAddress, ScriptControlChan};
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use geom::{Point2D, Rect};
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use geom::{Point2D, Rect, Size2D};
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use js::rust::Cx;
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use servo_msg::compositor_msg::PerformingLayout;
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use servo_msg::compositor_msg::ScriptListener;
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use servo_msg::constellation_msg::{ConstellationChan, WindowSizeData};
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use servo_msg::constellation_msg::{PipelineId, SubpageId};
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use servo_net::resource_task::ResourceTask;
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use servo_util::geometry::Au;
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use servo_util::geometry::{Au, MAX_RECT};
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use servo_util::geometry;
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use servo_util::str::DOMString;
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use servo_util::smallvec::{SmallVec1, SmallVec};
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use std::cell::Cell;
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use std::comm::{channel, Receiver, Empty, Disconnected};
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use std::mem::replace;
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use std::num::abs;
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use std::rc::Rc;
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use url::Url;
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@ -98,6 +100,10 @@ pub struct Page {
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/// Number of unnecessary potential reflows that were skipped since the last reflow
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pub avoided_reflows: Cell<int>,
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/// An enlarged rectangle around the page contents visible in the viewport, used
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/// to prevent creating display list items for content that is far away from the viewport.
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pub page_clip_rect: Cell<Rect<Au>>,
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}
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pub struct PageIterator {
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@ -164,6 +170,7 @@ impl Page {
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damaged: Cell::new(false),
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pending_reflows: Cell::new(0),
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avoided_reflows: Cell::new(0),
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page_clip_rect: Cell::new(MAX_RECT),
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}
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}
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@ -236,6 +243,49 @@ impl Page {
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}
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None
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}
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fn should_move_clip_rect(&self, clip_rect: Rect<Au>, new_viewport: Rect<f32>) -> bool{
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let clip_rect = Rect(Point2D(geometry::to_frac_px(clip_rect.origin.x) as f32,
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geometry::to_frac_px(clip_rect.origin.y) as f32),
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Size2D(geometry::to_frac_px(clip_rect.size.width) as f32,
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geometry::to_frac_px(clip_rect.size.height) as f32));
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// We only need to move the clip rect if the viewport is getting near the edge of
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// our preexisting clip rect. We use half of the size of the viewport as a heuristic
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// for "close."
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static VIEWPORT_SCROLL_MARGIN_SIZE: f32 = 0.5;
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let viewport_scroll_margin = new_viewport.size * VIEWPORT_SCROLL_MARGIN_SIZE;
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abs(clip_rect.origin.x - new_viewport.origin.x) <= viewport_scroll_margin.width ||
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abs(clip_rect.max_x() - new_viewport.max_x()) <= viewport_scroll_margin.width ||
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abs(clip_rect.origin.y - new_viewport.origin.y) <= viewport_scroll_margin.height ||
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abs(clip_rect.max_y() - new_viewport.max_y()) <= viewport_scroll_margin.height
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}
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pub fn set_page_clip_rect_with_new_viewport(&self, viewport: Rect<f32>) -> bool {
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// We use a clipping rectangle that is five times the size of the of the viewport,
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// so that we don't collect display list items for areas too far outside the viewport,
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// but also don't trigger reflows every time the viewport changes.
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static VIEWPORT_EXPANSION: f32 = 2.0; // 2 lengths on each side plus original length is 5 total.
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let proposed_clip_rect = geometry::f32_rect_to_au_rect(
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viewport.inflate(viewport.size.width * VIEWPORT_EXPANSION,
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viewport.size.height * VIEWPORT_EXPANSION));
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let clip_rect = self.page_clip_rect.get();
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if proposed_clip_rect == clip_rect {
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return false;
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}
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let had_clip_rect = clip_rect != MAX_RECT;
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if had_clip_rect && !self.should_move_clip_rect(clip_rect, viewport) {
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return false;
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}
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self.page_clip_rect.set(proposed_clip_rect);
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// If we didn't have a clip rect, the previous display doesn't need rebuilding
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// because it was built for infinite clip (MAX_RECT).
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had_clip_rect
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}
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}
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impl Iterator<Rc<Page>> for PageIterator {
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@ -375,6 +425,7 @@ impl Page {
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script_join_chan: join_chan,
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id: last_reflow_id.get(),
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query_type: query_type,
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page_clip_rect: self.page_clip_rect.get(),
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};
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let LayoutChan(ref chan) = self.layout_chan;
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