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qtqpainter

Qt, Set an exclusive clipping region

In Qt you can set a clipping region for a QPainter with modes ReplaceClip or IntesectClip but I miss an "ExcludeClip". How would you draw (filling) a "donut" (a circle with a transparent hole) without reverting to intermediate QPixmaps?

Solution

  • Found a solution operating with regions:

    QRegion rg1(outerRect,QRegion::Ellipse);
QRegion rg2(innerRect,QRegion::Ellipse);
QRegion rg3=rg1.subtracted(rg2);

painter->setClipRegion(rg3);