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

[Alexey Ushakov]

On Wed, 26 May 2021 13:49:24 GMT, Alexey Ushakov <avu at openjdk.org> wrote:

> Set black color for underlying window background to perform correct blending operations in metal with window surface destination

> _Mailing list message from [Alan Snyder](mailto:javalists at cbfiddle.com) on [awt-dev](mailto:awt-dev at mail.openjdk.java.net):_
> 
> Could the flashing problem be related to the timing problem described in JDK-8209329 <https://bugs.openjdk.java.net/browse/JDK-8209329>?
> 
> I have noticed occasional red flashes using Metal, which I suspect are caused by trying to render uninitialized data.
> (I?m guessing that the red is a debugging aid provided by Apple. Previously, they used yellow.)
> 
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Yes, blit encoder works asynchronously so we may have some latency before the actual content is presented to the window.

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PR: https://git.openjdk.java.net/jdk/pull/4206