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Separate computing a WR reference frame from adding it to the display list

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This commit is contained in:
Simon Sapin 2020-05-13 17:45:57 +02:00
parent 3e8623332b
commit c7acfc37ed
1 changed files with 36 additions and 27 deletions
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63
components/layout_2020/display_list/stacking_context.rs
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@ -364,6 +364,12 @@ impl Fragment {
}
}
struct ReferenceFrameData {
origin: crate::geom::PhysicalPoint<Length>,
transform: LayoutTransform,
kind: wr::ReferenceFrameKind,
}
impl BoxFragment {
fn get_stacking_context_type(&self) -> Option<StackingContextType> {
if self.style.establishes_stacking_context() {
@ -464,22 +470,24 @@ impl BoxFragment {
) {
// If we are creating a stacking context, we may also need to create a reference
// frame first.
let relative_border_rect = self
.border_rect()
.to_physical(self.style.writing_mode, &containing_block_info.rect);
let border_rect =
relative_border_rect.translate(containing_block_info.rect.origin.to_vector());
let established_reference_frame =
self.build_reference_frame_if_necessary(builder, &border_rect);
let reference_frame_data = self.reference_frame_data_if_necessary(containing_block_info);
// WebRender reference frames establish a new coordinate system at their origin
// (the border box of the fragment). We need to ensure that any coordinates we
// give to WebRender in this reference frame are relative to the fragment border
// box. We do this by adjusting the containing block origin.
let mut new_containing_block_info = containing_block_info.clone();
if established_reference_frame {
new_containing_block_info.rect.origin =
(-relative_border_rect.origin.to_vector()).to_point();
if let Some(reference_frame_data) = &reference_frame_data {
new_containing_block_info.rect.origin -= reference_frame_data.origin.to_vector();
builder.current_space_and_clip.spatial_id = builder.wr.push_reference_frame(
reference_frame_data.origin.to_webrender(),
builder.current_space_and_clip.spatial_id,
self.style.get_box().transform_style.to_webrender(),
wr::PropertyBinding::Value(reference_frame_data.transform),
reference_frame_data.kind,
);
builder.nearest_reference_frame = builder.current_space_and_clip.spatial_id;
}
let mut child_stacking_context = StackingContext::new(
@ -510,7 +518,7 @@ impl BoxFragment {
.stacking_contexts
.append(&mut stolen_children);
if established_reference_frame {
if reference_frame_data.is_some() {
builder.wr.pop_reference_frame();
}
}
@ -611,17 +619,22 @@ impl BoxFragment {
}
}
/// Build a reference frame for this fragment if it is necessary. Returns `true` if
/// a reference was built and `false` otherwise.
fn build_reference_frame_if_necessary(
/// Optionally returns the data for building a reference frame, without yet building it.
fn reference_frame_data_if_necessary(
&self,
builder: &mut StackingContextBuilder,
border_rect: &PhysicalRect<Length>,
) -> bool {
containing_block_info: &ContainingBlockInfo,
) -> Option<ReferenceFrameData> {
if !self.style.has_transform_or_perspective() {
return false;
return None;
}
let relative_border_rect = self
.border_rect()
.to_physical(self.style.writing_mode, &containing_block_info.rect);
let border_rect = relative_border_rect
.translate(containing_block_info.rect.origin.to_vector());
let untyped_border_rect = border_rect.to_untyped();
let transform = self.calculate_transform_matrix(&untyped_border_rect);
let perspective = self.calculate_perspective_matrix(&untyped_border_rect);
let (reference_frame_transform, reference_frame_kind) = match (transform, perspective) {
@ -641,15 +654,11 @@ impl BoxFragment {
(None, None) => unreachable!(),
};
builder.current_space_and_clip.spatial_id = builder.wr.push_reference_frame(
border_rect.origin.to_webrender(),
builder.current_space_and_clip.spatial_id,
self.style.get_box().transform_style.to_webrender(),
wr::PropertyBinding::Value(reference_frame_transform),
reference_frame_kind,
);
builder.nearest_reference_frame = builder.current_space_and_clip.spatial_id;
true
Some(ReferenceFrameData {
origin: border_rect.origin,
transform: reference_frame_transform,
kind: reference_frame_kind,
})
}
/// Returns the 4D matrix representing this fragment's transform.