REGRESSION (r164449): Subpixel rendering: http://www.apple.com/iphone-6/ "Faster wireless." image displays vertical black line on 1x displays at specific window width.
https://bugs.webkit.org/show_bug.cgi?id=144723
rdar://problem/18307094
Reviewed by Simon Fraser.
This patch ensures that the backing store's graphics layer is always positioned on a device pixel boundary.
While calculating the backing store's graphics layer location, its ancestor layer's compositing bounds is taken into account.
However the compositing bounds is an unsnapped value, so in order to place the graphics layer properly,
we need to pixel align the ancestor compositing bounds before using it to adjust the child's graphics layer position.
Source/WebCore:
Test: compositing/ancestor-compositing-layer-is-on-subpixel-position.html
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::updateGeometry):
LayoutTests:
* compositing/ancestor-compositing-layer-is-on-subpixel-position-expected.html: Added.
* compositing/ancestor-compositing-layer-is-on-subpixel-position.html: Added.
* platform/mac/compositing/layer-creation/overlap-animation-container-expected.txt: progression.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@183950 268f45cc-cd09-0410-ab3c-d52691b4dbfc
6 files changed
