RFR: 8303904: Transparent Windows Paint Wrong (Opaque) w/o Volatile Buffering

[Jeremy]

On Mon, 27 Mar 2023 21:45:08 GMT, Jeremy <duke at openjdk.org> wrote:

> The original write-up contains two complaints:
> 1. The window is opaque, so pixels that should be transparent are black.
> 2. The window is the wrong resolution. On a 200% resolution monitor it renders as if it were 100% (so it looks pixelated).
> 
> I recommend splitting this up into separate tickets.
> 
> This PR addresses the first (probably most offensive) issue: the window is now transparent.
> 
> I experimented with a change that resolves the second issue (image resolution) here:
> https://github.com/openjdk/jdk/commit/90735b7c01c66268776998c1b6aedc3250427002
> 
> ... that works, but IMO that looks riskier and should be part of a separate discussion.
> 
> I only have a Mac configured right now to test against, so I've confirmed the MTLGraphicsConfig and CGLGraphicsConfig changes. The other GraphicsConfig changes are identical, but I haven't confirmed that this new test passes in those environments. (I did confirm that those GraphicsConfig files appear to support getColorModel(Transparency.TRANSLUCENT), so I'm optimistic they'll be OK.

Alan, I may be confused. Does VAqua rely on turning off volatile buffering?

Or your comment might (?) make more sense if it's for my other PR ([for 8303950](https://github.com/openjdk/jdk/pull/12993)) that relates to this method:

https://github.com/openjdk/jdk/blob/a8871f5d26e5cb42c031c7b736ec30b1b147a2bc/src/java.desktop/share/classes/java/awt/Window.java#L3946-L3960

(Also: thanks for mentioning VAqua! I'll check it out. I was a big fan of Werner's Quaqua work a decade ago at another job.)

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PR Comment: https://git.openjdk.org/jdk/pull/13196#issuecomment-1500695845