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Correct traversal of transform tree ancestors.

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This code is only used when the TransformInterop feature is enabled.

The added test fails prior to the patch, with the TransformInterop
feature enabled, but passes either with the patch or without the
TransformInterop feature enabled.

Change-Id: I087c478c744531aa6120304e4e7df8ba35e2c0fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2774638
Commit-Queue: L. David Baron <dbaron@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#864565}
This commit is contained in:
L. David Baron
2021-03-19 04:48:13 +00:00
committed by Chromium LUCI CQ
parent e37b1ea8a8
commit cc62deee43
2 changed files with 57 additions and 6 deletions
cc/trees
draw_property_utils.cc
third_party/blink/web_tests/external/wpt/css/css-transforms
backface-visibility-with-sibling-001.html

19
cc/trees/draw_property_utils.cc

@ -412,15 +412,23 @@ bool IsTransformToRootOf3DRenderingContextBackFaceVisible(
const TransformNode& transform_node =
*transform_tree.Node(transform_tree_index);
if (transform_node.delegates_to_parent_for_backface)
const TransformNode* root_node = &transform_node;
if (transform_node.delegates_to_parent_for_backface) {
transform_tree_index = transform_node.parent_id;
root_node = transform_tree.Node(transform_tree_index);
}
int root_id = transform_tree_index;
int sorting_context_id = transform_node.sorting_context_id;
while (root_id > 0 && transform_tree.Node(root_id - 1)->sorting_context_id ==
sorting_context_id)
root_id--;
while (root_id > TransformTree::kRootNodeId) {
int parent_id = root_node->parent_id;
const TransformNode* parent_node = transform_tree.Node(parent_id);
if (parent_node->sorting_context_id != sorting_context_id)
break;
root_id = parent_id;
root_node = parent_node;
}
// TODO(chrishtr): cache this on the transform trees if needed, similar to
// |to_target| and |to_screen|.
@ -428,8 +436,7 @@ bool IsTransformToRootOf3DRenderingContextBackFaceVisible(
if (transform_tree_index != root_id)
property_trees->transform_tree.CombineTransformsBetween(
transform_tree_index, root_id, &to_3d_root);
to_3d_root.PreconcatTransform(
property_trees->transform_tree.Node(root_id)->to_parent);
to_3d_root.PreconcatTransform(root_node->to_parent);
return to_3d_root.IsBackFaceVisible();
}

44
third_party/blink/web_tests/external/wpt/css/css-transforms/backface-visibility-with-sibling-001.html vendored Normal file

@ -0,0 +1,44 @@
<!DOCTYPE HTML>
<title>backface-visibility test</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Google" href="http://www.google.com/">
<link rel="help" href="https://drafts.csswg.org/css-transforms-2/#3d-transform-rendering">
<link rel="match" href="/common/blank.html">
<meta name="assert" content="The backface-visibility property still works correctly when there is an element outside the 3-D rendering context that is, in tree order, in between the element with backface-visibility and the root of the 3-D Rendering Context">
<style>
div {
width: 100px;
height: 100px;
}
#outer {
transform-style: preserve-3d;
transform: rotateX(120deg);
position: relative;
}
#outer > div {
position: absolute;
top: 0;
left: 0;
}
#grandchild {
transform: translateZ(1px);
}
#child2 {
transform-style: preserve-3d;
transform: translateX(0);
backface-visibility: hidden;
background: red;
}
</style>
<div id="outer">
<div id="child1"><div id="grandchild"></div></div>
<div id="child2"></div>
</div>