third_party/WebKit/Source/platform/graphics/paint/README.md - Issue 1973343003: Initial implementation of GeometryMapper

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Unified Diff: third_party/WebKit/Source/platform/graphics/paint/README.md

Issue 1973343003: Initial implementation of GeometryMapper (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master

Patch Set: none Created 4 years, 6 months ago

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Index: third_party/WebKit/Source/platform/graphics/paint/README.md

diff --git a/third_party/WebKit/Source/platform/graphics/paint/README.md b/third_party/WebKit/Source/platform/graphics/paint/README.md

index 0bb62a6874e819ca63f9b6abfebed79040d7a9e2..618a5fc976f1998ab16f2eb4db73174ec2852f7a 100644

--- a/third_party/WebKit/Source/platform/graphics/paint/README.md

+++ b/third_party/WebKit/Source/platform/graphics/paint/README.md

@@ -234,3 +234,17 @@ to combine paint chunks into a smaller number of layers.

The owner of the `PaintArtifactCompositor` (e.g. `WebView`) can then attach its

root layer to the overall layer hierarchy to be displayed to the user.

+## Geometry routines

+The [`GeometryMapper`](GeometryMapper.h) is responsible for efficiently computing

+visual and transformed rects of display items in the coordinate space of ancestor

+[`PropertyTreeState`](PropertyTreeState.h)s.

+The transformed rect of a display item in an ancestor `PropertyTreeState` is that

+rect, multiplied by the transforms between the display item's `PropertyTreeState`

+and the ancestors, then flattened into 2D.

+The visual rect of a display item in an ancestor `PropertyTreeState` is the intersection

+of all of the intermediate clips (transformed in to the ancestor state), with

+the display item's transformed rect.