[webkit-changes] [WebKit/WebKit] 7eb6ed: visionOS: Text jumps by subpixel increments when r...

[Tim Horton]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7eb6ed02a5ba9ad174481b97bc76954169ca3608
      https://github.com/WebKit/WebKit/commit/7eb6ed02a5ba9ad174481b97bc76954169ca3608
  Author: Tim Horton <thorton at apple.com>
  Date:   2023-09-18 (Mon, 18 Sep 2023)

  Changed paths:
    M Source/WebKit/Shared/RemoteLayerTree/CGDisplayListImageBufferBackend.h
    M Source/WebKit/Shared/RemoteLayerTree/CGDisplayListImageBufferBackend.mm
    M Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.h
    M Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.mm

  Log Message:
  -----------
  visionOS: Text jumps by subpixel increments when repainting
https://bugs.webkit.org/show_bug.cgi?id=261472
rdar://109372324

Reviewed by Mike Wyrzykowski, Richard Robinson and Dean Jackson.

* Source/WebKit/Shared/RemoteLayerTree/CGDisplayListImageBufferBackend.h:
* Source/WebKit/Shared/RemoteLayerTree/CGDisplayListImageBufferBackend.mm:
(WebKit::GraphicsContextCGDisplayList::GraphicsContextCGDisplayList):
(WebKit::CGDisplayListImageBufferBackend::context):
* Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.h:
* Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.mm:
(WebKit::RemoteLayerBackingStore::paintContents):
(WebKit::RemoteLayerBackingStore::drawInContext):
(WebKit::RemoteLayerBackingStoreProperties::applyBackingStoreToLayer):
Now that it is possible to specify the resolution at which a dynamic content
scaling display list is recorded, plumb the backing store scale to that mechanism,
and remove all of our workarounds from the days when it was only recorded at 1x.

This fixes a bug where the integer rounding of the backing store size coupled
with subpixel CTMs would make text quantization cause glyphs to land at different
quantized positions between the 2x tiles and the 1x recorded display list.

Canonical link: https://commits.webkit.org/268107@main