In this screenshot of the JUCE demo*, the leftmost slider looks wrong:
To make it happen I just enabled
s->setBufferedToImage (true); for that slider, then ran the demo and played with the transform and this slider. In small transforms it happens.
I think that this happens due to this piece of code in juce_Component.cpp:
Graphics imG (image);
LowLevelGraphicsContext& lg = imG.getInternalContext();
lg.addTransform (AffineTransform::scale (scale));
for (const Rectangle<int>* i = validArea.begin(), * const e = validArea.end(); i != e; ++i)
lg.excludeClipRectangle (*i);
if (! owner.isOpaque())
{
lg.setFill (Colours::transparentBlack);
lg.fillRect (imageBounds, true);
lg.setFill (Colours::black);
}
owner.paintEntireComponent (imG, true);
The lg.fillRect (imageBounds, true); part is performed after lg.addTransform (AffineTransform::scale (scale)); which changes lg's coordinates from image-based to component-based.
It seems that changing it to lg.fillRect (compBounds, true); fixes this bug.
Cheers, Yair