Bug 213004

Summary: [WinCairo] Resizing window causes rendering glitches in accelerated compositing mode
Product: WebKit Reporter: Fujii Hironori <Hironori.Fujii>
Component: PlatformAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal    
Priority: P2    
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
[Patch] eglWaitNative workaround for WebKit1
none
[Patch] ANGLE_window_fixed_size none

Description Fujii Hironori 2020-06-09 17:37:18 PDT 
[WinCairo] Resizing window causes rendering glitches in accelerated compositing mode

1. Start WinCairo MiniBrowser of WebKit1 or WebKit2
2. Go to accelerated compositing mode page. For example, https://webkit.org/ and https://webkit.org/blog-files/3d-transforms/perspective-by-example.html
3. Resize the browser window wider and narrower
4. The content are distorted temporarily.

This issue happens both for WK1 and WK2 of WinCairo.
But, I think they aren't exactly same issue because of WK2's cross-process painting.
Comment 1 Fujii Hironori 2020-06-09 17:38:21 PDT 
Reported the bug to upsteam ANGLE.

4665 - D3D11: Resizing window is causing rendering gliches - angleproject
https://crbug.com/angleproject/4665
Comment 2 Fujii Hironori 2020-06-09 17:39:55 PDT 
Created attachment 401499 [details]
[Patch] eglWaitNative workaround for WebKit1

eglWaitNative workaround works only for WebKit1.

https://bugs.chromium.org/p/angleproject/issues/detail?id=4665#c2
Comment 3 Fujii Hironori 2020-06-09 17:42:56 PDT 
Created attachment 401500 [details]
[Patch] ANGLE_window_fixed_size

ANGLE has ANGLE_window_fixed_size extension.
It was introduced in the following bug.

320021 - Chrome renders window incorrectly on restore from minimize. - chromium
https://bugs.chromium.org/p/chromium/issues/detail?id=320021

I tried ANGLE_window_fixed_size extension in WinCairo WK1 and WK2, but it doesn't solve the bug.