Image 1 is basic image generated on Windows (software renderer).
Image 2 is generated on Windows by the following lines following the base image generation:
gd = ColourGradient(Colour(0x3bffffff), innerFlatRect.getCentreX(), innerFlatRect.getCentreY(), Colour(0x00000000), innerFlatRect.getCentreX(), innerFlatRect.getBottom(), true); g.setGradientFill(gd); g.fillEllipse(innerFlatRect);
Image 3 is basic image generated on Mac (Core Graphics renderer)
Image 4 is generated on Mac by the same lines as above following the base image generation.
You may see the same lines lead to different image on Mac and Windows.
Image 5 is generated on Mac by instead of Colour(0x00000000), Colour(0x00ffffff) was used.
Also on Windows both Colour(0x00000000) and Colour(0x00ffffff) lead to the same result.
As you may see there’s a problem or difference in implementation when both alpha channel and RGB gradients are used at the same time.