servo/components/gfx/display_list/optimizer.rs
2015-08-20 20:47:12 +08:00

90 lines
4.5 KiB
Rust

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Transforms a display list to produce a visually-equivalent, but cheaper-to-paint, one.
use display_list::{DisplayItem, DisplayList, StackingContext};
use euclid::rect::Rect;
use euclid::{Matrix2D, Matrix4};
use std::collections::linked_list::LinkedList;
use std::sync::Arc;
use util::geometry::{self, Au};
/// Transforms a display list to produce a visually-equivalent, but cheaper-to-paint, one.
pub struct DisplayListOptimizer {
/// The visible rect in page coordinates.
visible_rect: Rect<Au>,
}
impl DisplayListOptimizer {
/// Creates a new display list optimizer object. `visible_rect` specifies the visible rect in
/// page coordinates.
pub fn new(visible_rect: &Rect<f32>) -> DisplayListOptimizer {
DisplayListOptimizer {
visible_rect: geometry::f32_rect_to_au_rect(*visible_rect),
}
}
/// Optimizes the given display list, returning an equivalent, but cheaper-to-paint, one.
pub fn optimize(self, display_list: &DisplayList) -> DisplayList {
let mut result = DisplayList::new();
self.add_in_bounds_display_items(&mut result.background_and_borders,
display_list.background_and_borders.iter());
self.add_in_bounds_display_items(&mut result.block_backgrounds_and_borders,
display_list.block_backgrounds_and_borders.iter());
self.add_in_bounds_display_items(&mut result.floats, display_list.floats.iter());
self.add_in_bounds_display_items(&mut result.content, display_list.content.iter());
self.add_in_bounds_display_items(&mut result.positioned_content,
display_list.positioned_content.iter());
self.add_in_bounds_display_items(&mut result.outlines,
display_list.outlines.iter());
self.add_in_bounds_stacking_contexts(&mut result.children, display_list.children.iter());
result
}
/// Adds display items that intersect the visible rect to `result_list`.
fn add_in_bounds_display_items<'a, I>(&self,
result_list: &mut LinkedList<DisplayItem>,
display_items: I)
where I: Iterator<Item=&'a DisplayItem> {
for display_item in display_items {
if self.visible_rect.intersects(&display_item.base().bounds) &&
display_item.base().clip.might_intersect_rect(&self.visible_rect) {
result_list.push_back((*display_item).clone())
}
}
}
/// Adds child stacking contexts whose boundaries intersect the visible rect to `result_list`.
fn add_in_bounds_stacking_contexts<'a, I>(&self,
result_list: &mut LinkedList<Arc<StackingContext>>,
stacking_contexts: I)
where I: Iterator<Item=&'a Arc<StackingContext>> {
for stacking_context in stacking_contexts {
if stacking_context.layer.is_none() {
// Transform this stacking context to get it into the same space as
// the parent stacking context.
let origin_x = stacking_context.bounds.origin.x.to_f32_px();
let origin_y = stacking_context.bounds.origin.y.to_f32_px();
let transform = Matrix4::identity().translate(origin_x,
origin_y,
0.0)
.mul(&stacking_context.transform);
let transform_2d = Matrix2D::new(transform.m11, transform.m12,
transform.m21, transform.m22,
transform.m41, transform.m42);
let overflow = geometry::au_rect_to_f32_rect(stacking_context.overflow);
let overflow = transform_2d.transform_rect(&overflow);
let overflow = geometry::f32_rect_to_au_rect(overflow);
if self.visible_rect.intersects(&overflow) {
result_list.push_back((*stacking_context).clone())
}
}
}
}
}