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Unified Diff: cc/trees/property_tree.h

Issue 2733633002: Handle nested position:sticky elements correctly (compositor) (Closed)
Patch Set: More layer id fixes Created 3 years, 9 months ago
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Index: cc/trees/property_tree.h
diff --git a/cc/trees/property_tree.h b/cc/trees/property_tree.h
index f7e90ea7b47277c8df23da1df91cfd84ecc80de1..ef3fc27ea70a636a5df872ae124a500271318b69 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -104,17 +104,7 @@ class CC_EXPORT PropertyTree {
PropertyTrees* property_trees_;
};
-struct StickyPositionNodeData {
- int scroll_ancestor;
- LayerStickyPositionConstraint constraints;
-
- // This is the offset that blink has already applied to counteract the main
- // thread scroll offset of the scroll ancestor. We need to account for this
- // by computing the additional offset necessary to keep the element stuck.
- gfx::Vector2dF main_thread_offset;
-
- StickyPositionNodeData() : scroll_ancestor(-1) {}
-};
+struct StickyPositionNodeData;
class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
public:
@@ -277,6 +267,35 @@ class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
std::vector<StickyPositionNodeData> sticky_position_data_;
};
+struct StickyPositionNodeData {
+ int scroll_ancestor;
+ LayerStickyPositionConstraint constraints;
+
+ // This is the offset that blink has already applied to counteract the main
+ // thread scroll offset of the scroll ancestor. We need to account for this
+ // by computing the additional offset necessary to keep the element stuck.
+ gfx::Vector2dF main_thread_offset;
+
+ // In order to properly compute the sticky offset, we need to know if we have
+ // any sticky ancestors both between ourselves and our containing block and
+ // between our containing block and the viewport. These ancestors are then
+ // used to correct the constraining rect locations.
+ int nearest_node_shifting_sticky_box;
+ int nearest_node_shifting_containing_block;
+
+ // For performance we cache our accumulated sticky offset to allow descendant
+ // sticky elements to offset their constraint rects. Because we can either
+ // affect the sticky box constraint rect or the containing block constraint
+ // rect, we need to accumulate both.
+ gfx::Vector2dF total_sticky_box_sticky_offset;
+ gfx::Vector2dF total_containing_block_sticky_offset;
+
+ StickyPositionNodeData()
+ : scroll_ancestor(TransformTree::kInvalidNodeId),
+ nearest_node_shifting_sticky_box(TransformTree::kInvalidNodeId),
+ nearest_node_shifting_containing_block(TransformTree::kInvalidNodeId) {}
+};
+
class CC_EXPORT ClipTree final : public PropertyTree<ClipNode> {
public:
bool operator==(const ClipTree& other) const;

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