RFR: 8252255: Blurry rendering of SwingNode with HiDPI scaling in JavaFX

[Ajit Ghaisas]

On Fri, 3 Mar 2023 08:07:12 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

> Refactor-ed Swing interop was calling `JLightweightFrame.notifyDisplayChanged()` with [wrong scale factor](https://github.com/openjdk/jfx/blob/master/modules/javafx.swing/src/main/java/com/sun/javafx/embed/swing/newimpl/SwingNodeInteropN.java#L71-L76) 
> as it was passing integer scale and not double so scalefactor of 1.25 is being passed as 1.0 to JLightwieightFrame
> Due to this, the `imagebuffer `which is created for lightweight container to paint its content to an offscreen image 
> is created with wrong[ width/height ](https://github.com/openjdk/jdk/blob/master/src/java.desktop/share/classes/sun/swing/JLightweightFrame.java#L457)
> Fix is made to have Swing interop call double version of the method to get correct scale factor and set the imagebuffer properly.
> 
> I guess we could remove the int version of the method (which anyways is deprecated) and cleanup Swing interop code to just utilise the double version, as all platforms we support uses floating scale, but that cleanup can be done separately for another day

The fix looks fine.

I think, an automated JavaFX system test can be developed to validate this fix.
You will need to do it as a separate JBS issue since the code repositories are different.

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PR: https://git.openjdk.org/jdk/pull/12848