[webkit-changes] [WebKit/WebKit] b51c7a: Drawing SystemImages have multiple context state h...

[Kimmo Kinnunen]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: b51c7a93f9151e1d799a6a399274e0d84def4144
      https://github.com/WebKit/WebKit/commit/b51c7a93f9151e1d799a6a399274e0d84def4144
  Author: Kimmo Kinnunen <kkinnunen at apple.com>
  Date:   2023-03-12 (Sun, 12 Mar 2023)

  Changed paths:
    M Source/WebCore/Modules/applepay/ApplePayLogoSystemImage.mm
    M Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp
    M Tools/TestWebKitAPI/Tests/WebCore/DisplayListRecorderTests.cpp

  Log Message:
  -----------
  Drawing SystemImages have multiple context state handling errors
https://bugs.webkit.org/show_bug.cgi?id=253640
rdar://106502760

Reviewed by Simon Fraser.

Problems :
1. Drawing system images through display list recorder would not apply
   the pending graphics context state. This could, for example, leave
   out antialias setting when it would be intended.
2. Drawing ApplePay system image would change the graphics context
   transform but not reset it.
3. The drawing implementation of the ApplePay image is custom, it might
   further mutate the CGContext without WebKit knowing it. It would
   mutate at least the clip state of the underlying CGContext.
   This could cause rendering problems until the state stack would
   reset the clip.

Fix 1. by making DisplayListRecorder apply the pending state before
recording the draw item.

Fix 2., 3. by adding CGContextSaveGState() and corresponding restore.
Also use the CGContext methods instead of GraphicsContext methods,
for consistency. Future commits might add mechanisms to ensure bugs
like this are harder to do.

* Source/WebCore/Modules/applepay/ApplePayLogoSystemImage.mm:
(WebCore::ApplePayLogoSystemImage::draw const):
* Source/WebCore/platform/graphics/displaylists/DisplayListRecorder.cpp:
(WebCore::DisplayList::Recorder::drawSystemImage):
* Tools/TestWebKitAPI/Tests/WebCore/DisplayListRecorderTests.cpp:

Canonical link: https://commits.webkit.org/261549@main