https://bugs.webkit.org/show_bug.cgi?id=219017
<rdar://problem/71454799>
Reviewed by Simon Fraser.
Source/WebKit:
Test: compositing/repaint/transparent-layer-repaint.html
* Shared/RemoteLayerTree/RemoteLayerBackingStore.mm:
(WebKit::RemoteLayerBackingStore::display):
I accidentally lost the Copy composite operator in r269824, causing
the repaint copy-forward to blend instead of just copying.
This wreaks havoc on layers with contents with colors that have 0 < alpha < 1,
because every repaint means the colors intensify.
LayoutTests:
* compositing/repaint/transparent-layer-repaint-expected.html: Added.
* compositing/repaint/transparent-layer-repaint.html: Added.
Add a test that:
- repaints a backingstoreful compositing layer
- more than once
- in a small enough area that we use partial repaint
- with partially-transparent pixels
And then ensures that the background of that layer (the non-repainted part)
remains the color that it should.
Canonical link: https://commits.webkit.org/231648@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@269895 268f45cc-cd09-0410-ab3c-d52691b4dbfc
