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-rw-r--r--components/layout/display_list/builder.rs10
-rw-r--r--components/layout/display_list/items.rs6
-rw-r--r--components/layout/flow.rs20
-rw-r--r--components/layout/fragment.rs6
-rw-r--r--components/layout/inline.rs5
-rw-r--r--components/layout/traversal.rs4
-rw-r--r--components/layout_2020/display_list/stacking_context.rs21
-rw-r--r--tests/wpt/mozilla/meta/MANIFEST.json17
-rw-r--r--tests/wpt/mozilla/tests/css/stacking-context-empty-ref.html1
-rw-r--r--tests/wpt/mozilla/tests/css/stacking-context-empty.html14
10 files changed, 103 insertions, 1 deletions
diff --git a/components/layout/display_list/builder.rs b/components/layout/display_list/builder.rs
index 9d5f1e100ab..0be8183e2a7 100644
--- a/components/layout/display_list/builder.rs
+++ b/components/layout/display_list/builder.rs
@@ -1571,6 +1571,11 @@ impl Fragment {
return;
}
+ // If this fragment takes up no space, we don't need to build any display items for it.
+ if self.has_non_invertible_transform() {
+ return;
+ }
+
debug!(
"Fragment::build_display_list at rel={:?}, abs={:?}: {:?}",
self.border_box, stacking_relative_border_box, self
@@ -2376,6 +2381,11 @@ impl BlockFlow {
state: &mut StackingContextCollectionState,
flags: StackingContextCollectionFlags,
) {
+ // This block flow produces no stacking contexts if it takes up no space.
+ if self.has_non_invertible_transform() {
+ return;
+ }
+
let mut preserved_state = SavedStackingContextCollectionState::new(state);
let stacking_context_type = self.stacking_context_type(flags);
diff --git a/components/layout/display_list/items.rs b/components/layout/display_list/items.rs
index 27b4ec1fa88..4800abe7e53 100644
--- a/components/layout/display_list/items.rs
+++ b/components/layout/display_list/items.rs
@@ -217,6 +217,12 @@ impl StackingContext {
parent_clipping_and_scrolling: ClippingAndScrolling,
established_reference_frame: Option<ClipScrollNodeIndex>,
) -> StackingContext {
+ if let Some(ref t) = transform {
+ // These are used as scale values by webrender, and it can't handle
+ // divisors of 0 when scaling.
+ assert_ne!(t.m11, 0.);
+ assert_ne!(t.m22, 0.);
+ }
StackingContext {
id,
context_type,
diff --git a/components/layout/flow.rs b/components/layout/flow.rs
index c2d01b7f9f9..acea20ad4d4 100644
--- a/components/layout/flow.rs
+++ b/components/layout/flow.rs
@@ -273,6 +273,22 @@ pub trait Flow: HasBaseFlow + fmt::Debug + Sync + Send + 'static {
might_have_floats_in_or_out
}
+ fn has_non_invertible_transform(&self) -> bool {
+ if !self.class().is_block_like() ||
+ self.as_block()
+ .fragment
+ .style
+ .get_box()
+ .transform
+ .0
+ .is_empty()
+ {
+ return false;
+ }
+
+ self.as_block().fragment.has_non_invertible_transform()
+ }
+
fn get_overflow_in_parent_coordinates(&self) -> Overflow {
// FIXME(#2795): Get the real container size.
let container_size = Size2D::zero();
@@ -1160,7 +1176,9 @@ impl BaseFlow {
state: &mut StackingContextCollectionState,
) {
for kid in self.children.iter_mut() {
- kid.collect_stacking_contexts(state);
+ if !kid.has_non_invertible_transform() {
+ kid.collect_stacking_contexts(state);
+ }
}
}
diff --git a/components/layout/fragment.rs b/components/layout/fragment.rs
index 062db9c0a7e..10c0fb072cc 100644
--- a/components/layout/fragment.rs
+++ b/components/layout/fragment.rs
@@ -2730,6 +2730,12 @@ impl Fragment {
self.style().get_box().perspective != Perspective::None
}
+ /// Returns true if this fragment has a transform applied that causes it to take up no space.
+ pub fn has_non_invertible_transform(&self) -> bool {
+ self.transform_matrix(&Rect::default())
+ .map_or(false, |matrix| !matrix.is_invertible())
+ }
+
/// Returns true if this fragment establishes a new stacking context and false otherwise.
pub fn establishes_stacking_context(&self) -> bool {
// Text fragments shouldn't create stacking contexts.
diff --git a/components/layout/inline.rs b/components/layout/inline.rs
index dfdb20e309b..ee9980c4f1a 100644
--- a/components/layout/inline.rs
+++ b/components/layout/inline.rs
@@ -1871,6 +1871,11 @@ impl Flow for InlineFlow {
let previous_cb_clipping_and_scrolling = state.containing_block_clipping_and_scrolling;
for fragment in self.fragments.fragments.iter_mut() {
+ // If a particular fragment would establish a stacking context but has a transform
+ // applied that causes it to take up no space, we can skip it entirely.
+ if fragment.has_non_invertible_transform() {
+ continue;
+ }
state.containing_block_clipping_and_scrolling = previous_cb_clipping_and_scrolling;
let abspos_containing_block = fragment.style.get_box().position != Position::Static;
diff --git a/components/layout/traversal.rs b/components/layout/traversal.rs
index 88a6514433b..5c66004bc1a 100644
--- a/components/layout/traversal.rs
+++ b/components/layout/traversal.rs
@@ -346,6 +346,10 @@ pub struct BuildDisplayList<'a> {
impl<'a> BuildDisplayList<'a> {
#[inline]
pub fn traverse(&mut self, flow: &mut dyn Flow) {
+ if flow.has_non_invertible_transform() {
+ return;
+ }
+
let parent_stacking_context_id = self.state.current_stacking_context_id;
self.state.current_stacking_context_id = flow.base().stacking_context_id;
diff --git a/components/layout_2020/display_list/stacking_context.rs b/components/layout_2020/display_list/stacking_context.rs
index fce6fb6caec..05c2d7558a9 100644
--- a/components/layout_2020/display_list/stacking_context.rs
+++ b/components/layout_2020/display_list/stacking_context.rs
@@ -447,6 +447,14 @@ impl Fragment {
return;
}
+ // If this fragment has a transform applied that makes it take up no spae
+ // then we don't need to create any stacking contexts for it.
+ let has_non_invertible_transform =
+ fragment.has_non_invertible_transform(&containing_block_info.rect.to_untyped());
+ if has_non_invertible_transform {
+ return;
+ }
+
fragment.build_stacking_context_tree(
fragment_ref,
builder,
@@ -775,6 +783,15 @@ impl BoxFragment {
})
}
+ /// Returns true if the given style contains a transform that is not invertible.
+ fn has_non_invertible_transform(&self, containing_block: &Rect<Length>) -> bool {
+ let list = &self.style.get_box().transform;
+ match list.to_transform_3d_matrix(Some(containing_block)) {
+ Ok(t) => !t.0.is_invertible(),
+ Err(_) => false,
+ }
+ }
+
/// Returns the 4D matrix representing this fragment's transform.
pub fn calculate_transform_matrix(
&self,
@@ -783,6 +800,10 @@ impl BoxFragment {
let list = &self.style.get_box().transform;
let transform =
LayoutTransform::from_untyped(&list.to_transform_3d_matrix(Some(&border_rect)).ok()?.0);
+ // WebRender will end up dividing by the scale value of this transform, so we
+ // want to ensure we don't feed it a divisor of 0.
+ assert_ne!(transform.m11, 0.);
+ assert_ne!(transform.m22, 0.);
let transform_origin = &self.style.get_box().transform_origin;
let transform_origin_x = transform_origin
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 5ce021feee6..47ba62031be 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -6080,6 +6080,19 @@
{}
]
],
+ "stacking-context-empty.html": [
+ "952c73f1680805dc3a976446bb509cb924a6a702",
+ [
+ null,
+ [
+ [
+ "/_mozilla/css/stacking-context-empty-ref.html",
+ "=="
+ ]
+ ],
+ {}
+ ]
+ ],
"stacking_context_overflow_a.html": [
"dc379afb77977b0e99a0a8ce3321c9afff236a37",
[
@@ -10311,6 +10324,10 @@
"0525bab6b11800d29f90efc7efef0f43165fba01",
[]
],
+ "stacking-context-empty-ref.html": [
+ "8006e2413694b0776f000d3b8138bed29812b7cd",
+ []
+ ],
"stacking_context_overflow_ref.html": [
"49991c449ab4f42afae6f512a7f184e70d77bc34",
[]
diff --git a/tests/wpt/mozilla/tests/css/stacking-context-empty-ref.html b/tests/wpt/mozilla/tests/css/stacking-context-empty-ref.html
new file mode 100644
index 00000000000..8006e241369
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/stacking-context-empty-ref.html
@@ -0,0 +1 @@
+<p><img src="100x100_green.png">
diff --git a/tests/wpt/mozilla/tests/css/stacking-context-empty.html b/tests/wpt/mozilla/tests/css/stacking-context-empty.html
new file mode 100644
index 00000000000..952c73f1680
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/stacking-context-empty.html
@@ -0,0 +1,14 @@
+<link rel="match" href="stacking-context-empty-ref.html">
+<style>
+ div {
+ border-radius: 2px;
+ background: #777;
+ border-bottom: 1px solid #f1f1f1;
+ }
+.test {
+ transform: scaleX(0);
+}
+</style>
+<p><img src="100x100_green.png">
+<div class="test">aaa</div>
+<p><img class="test" src="100x100_green.png">
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-17 07:20:40 +0000