[13] RFR 8214109: XToolkit is not correctly displayed color on 16-bit high color setting

[Dmitry Markov]

Hello,

Could you review a fix for jdk13, please?

        bug: https://bugs.openjdk.java.net/browse/JDK-8214109 
<https://bugs.openjdk.java.net/browse/JDK-8214109>
        webrev: http://cr.openjdk.java.net/~dmarkov/8214109/webrev.00/ 
<http://cr.openjdk.java.net/~dmarkov/8214109/webrev.00/>

Problem description:  
On xvnc4 environment the colour of the background and the colour of the repaint 
area may be different (and it’s visually noticeable) even if the same colour is 
specified. The root cause of this behaviour is that we always use ColorModel to 
calculate a pixel value in XWindow.xSetBackground() and at the same time the 
pixel value for repaint area is calculated using SurfaceData methods, (e.g. 
SurfaceData.pixelFor()). Actually this is regression caused by JDK-6304250 
which introduced ColorModel based calculation of the pixel value to fix problem 
for OpenGL pipeline.   

Fix:  
It is necessary to modify XWindow.xSetBackground(): if OpenGL pipeline is 
enabled we should use ColorModel to calculate the pixel value; otherwise we 
should use SurfaceData.pixelFor() for calculation.

Thanks,
Dmitry