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

[Prasanta Sadhukhan]

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

I actually tried testing the LightweightFrame scale factor by adding check in reproducer `BlurrySwingNode` testcase


System.setProperty("sun.java2d.uiScale", "1.25");
Object lwFrame = com.sun.javafx.embed.swing.SwingNodeHelper.getLightweightFrame(swingLabelNode);
           assertEquals(1.25, ((sun.swing.JLightweightFrame)lwFrame).getScaleFactorX());

but I get an error for module visibility for fx swing module, although sun.swing module is being made visible

`javac --add-modules javafx.swing --add-exports javafx.swing/com.sun.javafx.embed.swing=ALL-UNNAMED --add-modules java.desktop --add-exports java.desktop/sun.swing=ALL-UNNAMED BlurrySwingNode.java`

BlurrySwingNode.java:49: error: cannot find symbol
            Object lwFrame = com.sun.javafx.embed.swing.SwingNodeHelper.getLightweightFrame(swingLabelNode);
                                                                       ^
  symbol:   method getLightweightFrame(SwingNode)
  location: class SwingNodeHelper
BlurrySwingNode.java:50: warning: JLightweightFrame is internal proprietary API and may be removed in a future release
            System.out.println(((sun.swing.JLightweightFrame)lwFrame).getScaleFactorX());
1 error
1 warning

@kevinrushforth @aghaisas Do you have any idea on this?

-------------

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