<AWT Dev> RFR: 8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL [v2]

[Alexey Ushakov]

On Sun, 8 Aug 2021 23:29:48 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> Thank you, looking into it.
>
> I check the steps below and was able to reproduce the same artifacts(black rectangles) in the tree tab with the current version of the fix. And I do not see a big difference between setting the layer to YES at the beginning or a little bit later, at the end, it will be opaque and artifacts occur.
> 
> 1. Run SwingSet2
> 2. Click on all tabs starting from the second one, delay on each tab for the second or so
> 3. On the tab with swing tree control try to expand some tree nodes -> you'll see black rectangles while performing the clicks
> 4. Repeat from step 2 if no artifacts are visible

Interesting, now I'm also able to reproduce this problem with the latest version of the fix. Actually, looks like the problem exists even without the fix. We get invalid background with the same scenario. It's not so visible because of default L&F (light). Nevertheless, the color of the background is not exact the same. If we provide apple.awt.application.appearance=NSAppearanceNameDarkAqua  VM option, the problem became visible with metal and not reproducible with OGL.

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PR: https://git.openjdk.java.net/jdk/pull/4946