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

[Kevin Rushforth]

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

Looks good now. In addition to verifying this visually at various screen scales, I instrumented the JavaFX SwingNode code and verified that, with your patch, SwingNode now calls the newly added `notifyDisplayChanged(double, double)` method, rather than falling back to the `notifyDisplayChanged(int)` method.

Does this need a CSR?

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Marked as reviewed by kcr (Author).

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