Bad rendering when scrolling iPhone SE page

[Dean Jackson]

Scrolling on https://www.apple.com/iphone-se/ iPhone SE images renders with black box around iPhone image, leaves traces of the image as you scroll, and if scrolled at a very slow speed small blac k squares can be found int he images as well. 

Steps To Reproduce:
1. Go to https://www.apple.com/iphone-se/ 
2. Start to scroll at a moderate speed and observe the iPhone SE images renders with black box around iPhone image and leaves traces of the image as you scroll.

[Dean Jackson]

<rdar://problem/64179949>

[Kenneth Russell]

What hardware does this reproduce on?

It doesn't seem to occur on a 15" 2017 MacBook Pro with dual Intel HD Graphics 630 and AMD Radeon Pro 560 GPUs. Tested with both the Intel (default) as well as the AMD GPUs as the active GPU, in MiniBrowser with WK1.

[Kenneth Russell]

Also, "run-safari --debug" no longer works on this machine (running macOS 10.15.5):

$ ./Tools/Scripts/run-safari --debug
Starting SafariForWebKitDevelopment with DYLD_FRAMEWORK_PATH set to point to built WebKit in /Users/kbr/src/WebKit/WebKitBuild/Debug.
dyld: Symbol not found: _WKBundlePageCopyRenderLayerTree
  Referenced from: /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari
  Expected in: /Users/kbr/src/WebKit/WebKitBuild/Debug/WebKit.framework/Versions/A/WebKit
 in /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari

[Kenneth Russell]

Can't reproduce in MiniBrowser with WK2 either. With WK2 the high-performance GPU is selected by default. Modifying Source/WebCore/platform/graphics/cocoa/GraphicsContextGLOpenGLCocoa.mm to always set:
  m_powerPreferenceUsedForCreation = GraphicsContextGLPowerPreference::Default;
still doesn't reproduce.

[Simon Fraser (smfr)]

> $ ./Tools/Scripts/run-safari --debug
> Starting SafariForWebKitDevelopment with DYLD_FRAMEWORK_PATH set to point to
> built WebKit in /Users/kbr/src/WebKit/WebKitBuild/Debug.
> dyld: Symbol not found: _WKBundlePageCopyRenderLayerTree
>   Referenced from:
> /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari
>   Expected in:
> /Users/kbr/src/WebKit/WebKitBuild/Debug/WebKit.framework/Versions/A/WebKit
>  in /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari

Bug 214947.

[Dean Jackson]

I'm no longer seeing it on a Mac Pro. Trying other devices.

It took me a while to reproduce the first time.

[Dean Jackson]

Attaching the original screenshots. It could well have been an image decoding issue, although I think this JS component made its own masking format for these animations.

[Dean Jackson]

Created attachment 405525 [details]
screenshot1

[Dean Jackson]

Created attachment 405526 [details]
screenshot2

[Kate Cheney]

(In reply to Kenneth Russell from comment #3)
> Also, "run-safari --debug" no longer works on this machine (running macOS
> 10.15.5):
> 
> $ ./Tools/Scripts/run-safari --debug
> Starting SafariForWebKitDevelopment with DYLD_FRAMEWORK_PATH set to point to
> built WebKit in /Users/kbr/src/WebKit/WebKitBuild/Debug.
> dyld: Symbol not found: _WKBundlePageCopyRenderLayerTree
>   Referenced from:
> /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari
>   Expected in:
> /Users/kbr/src/WebKit/WebKitBuild/Debug/WebKit.framework/Versions/A/WebKit
>  in /System/Library/PrivateFrameworks/Safari.framework/Versions/A/Safari

This was fixed in Bug 214947.

[Kenneth Russell]

Thanks for the fix to the run-safari script!

[Dean Jackson]

What hardware were you looking at Ken? Justin was unable to reproduce it on an iMac Pro.

[Dean Jackson]

OK. No longer reproduces with trunk builds on any hardware I tried.

[Kenneth Russell]

That's a relief!