commit 68f0638062a25c387c9c7c0441358ac508de18e6
parent 7b2ae9ebd5a9a60e001b0db1616aa190bde4a39a
Author: Glenn Watson <git@chillybin.org>
Date: Wed, 12 Nov 2025 04:15:56 +0000
Bug 1999575 - Ensure that fractional external scroll offsets from parent nodes do not affect local snapping r=gfx-reviewers,lsalzman
Differential Revision: https://phabricator.services.mozilla.com/D272182
Diffstat:
4 files changed, 80 insertions(+), 23 deletions(-)
diff --git a/gfx/wr/webrender/src/spatial_tree.rs b/gfx/wr/webrender/src/spatial_tree.rs
@@ -116,6 +116,40 @@ impl ops::Not for VisibleFace {
pub trait SpatialNodeContainer {
/// Get the common information for a given spatial node
fn get_node_info(&self, index: SpatialNodeIndex) -> SpatialNodeInfo;
+
+ fn get_snapping_info(
+ &self,
+ parent_index: Option<SpatialNodeIndex>
+ ) -> Option<(ScaleOffset, LayoutVector2D)> {
+ match parent_index {
+ Some(parent_index) => {
+ let node_info = self.get_node_info(parent_index);
+
+ match node_info.snapping_transform {
+ Some(snapping_transform) => {
+ let content_offset = match node_info.node_type {
+ SpatialNodeType::StickyFrame(ref info) => {
+ info.previously_applied_offset
+ }
+ SpatialNodeType::ScrollFrame(ref info) => {
+ info.external_scroll_offset
+ }
+ SpatialNodeType::ReferenceFrame(..) => {
+ LayoutVector2D::zero()
+ }
+ };
+ Some((snapping_transform, content_offset))
+ }
+ None => {
+ None
+ }
+ }
+ }
+ None => {
+ Some((ScaleOffset::identity(), LayoutVector2D::zero()))
+ }
+ }
+ }
}
#[cfg_attr(feature = "capture", derive(Serialize))]
@@ -438,17 +472,10 @@ impl SceneSpatialTree {
mut node: SceneSpatialNode,
uid: SpatialNodeUid,
) -> SpatialNodeIndex {
- let parent_snapping_transform = match node.parent {
- Some(parent_index) => {
- self.get_node_info(parent_index).snapping_transform
- }
- None => {
- Some(ScaleOffset::identity())
- }
- };
+ let parent_info = self.get_snapping_info(node.parent);
node.snapping_transform = calculate_snapping_transform(
- parent_snapping_transform,
+ parent_info,
&node.descriptor.node_type,
);
@@ -1206,19 +1233,13 @@ impl SpatialTree {
node_index: SpatialNodeIndex,
scene_properties: &SceneProperties,
) {
- let parent_snapping_transform = match self.get_spatial_node(node_index).parent {
- Some(parent_index) => {
- self.get_node_info(parent_index).snapping_transform
- }
- None => {
- Some(ScaleOffset::identity())
- }
- };
+ let parent_index = self.get_spatial_node(node_index).parent;
+ let parent_info = self.get_snapping_info(parent_index);
let node = &mut self.spatial_nodes[node_index.0 as usize];
node.snapping_transform = calculate_snapping_transform(
- parent_snapping_transform,
+ parent_info,
&node.node_type,
);
@@ -1399,27 +1420,39 @@ pub fn get_external_scroll_offset<S: SpatialNodeContainer>(
}
fn calculate_snapping_transform(
- parent_snapping_transform: Option<ScaleOffset>,
+ parent_info: Option<(ScaleOffset, LayoutVector2D)>,
node_type: &SpatialNodeType,
) -> Option<ScaleOffset> {
// We need to incorporate the parent scale/offset with the child.
// If the parent does not have a scale/offset, then we know we are
// not 2d axis aligned and thus do not need to snap its children
// either.
- let parent_scale_offset = match parent_snapping_transform {
- Some(parent_snapping_transform) => parent_snapping_transform,
+ let (parent_scale_offset, content_fract_offset) = match parent_info {
+ Some((transform, content_offset)) => {
+ (
+ transform,
+ LayoutVector2D::new(
+ content_offset.x.fract(),
+ content_offset.y.fract(),
+ )
+ )
+ }
None => return None,
};
let scale_offset = match node_type {
SpatialNodeType::ReferenceFrame(ref info) => {
+ // Ensure that if a parent external scroll offset has a fractional component
+ // that this doesn't affect the snapping calculations during scene building
+ // (the overall scroll offset is snapped to device pixel by the spatial tree)
+ let origin_offset = info.origin_in_parent_reference_frame - content_fract_offset;
+
match info.source_transform {
PropertyBinding::Value(ref value) => {
// We can only get a ScaleOffset if the transform is 2d axis
// aligned.
match ScaleOffset::from_transform(value) {
Some(scale_offset) => {
- let origin_offset = info.origin_in_parent_reference_frame;
scale_offset.then(&ScaleOffset::from_offset(origin_offset.to_untyped()))
}
None => return None,
@@ -1430,7 +1463,6 @@ fn calculate_snapping_transform(
// We still want to incorporate the reference frame offset however.
// TODO(aosmond): Is there a better known starting point?
PropertyBinding::Binding(..) => {
- let origin_offset = info.origin_in_parent_reference_frame;
ScaleOffset::from_offset(origin_offset.to_untyped())
}
}
diff --git a/gfx/wr/wrench/reftests/snap/content-offset-ref.yaml b/gfx/wr/wrench/reftests/snap/content-offset-ref.yaml
@@ -0,0 +1,6 @@
+---
+root:
+ items:
+ - type: rect
+ bounds: [ 125, 25, 50, 50 ]
+ color: green
diff --git a/gfx/wr/wrench/reftests/snap/content-offset.yaml b/gfx/wr/wrench/reftests/snap/content-offset.yaml
@@ -0,0 +1,18 @@
+# Ensure that if a parent external scroll offset has a fractional component
+# that this doesn't affect the snapping calculations during scene building
+# (the overall scroll offset is snapped to device pixel by the spatial tree)
+---
+root:
+ items:
+ - type: scroll-frame
+ bounds: [0, 0, 200, 100]
+ content-size: [200, 200]
+ scroll-offset: [0, 100]
+ external-scroll-offset: [0, 50.1]
+ items:
+ - type: stacking-context
+ transform: translate(100, 0.4)
+ items:
+ - type: rect
+ bounds: [ 25, 125, 50, 50 ]
+ color: green
diff --git a/gfx/wr/wrench/reftests/snap/reftest.list b/gfx/wr/wrench/reftests/snap/reftest.list
@@ -4,3 +4,4 @@ platform(linux,mac) == preserve-3d.yaml preserve-3d.png
fuzzy(128,200) == subpixel-raster-root.yaml subpixel-raster-root-ref.yaml
platform(linux,mac) == fractional-filter.yaml fractional-filter-ref.yaml
max_surface_size(256) == 1761299.yaml 1761299.yaml
+== content-offset.yaml content-offset-ref.yaml
