My mask is a 1Bit QImage (Mono).

i thought, that i can handle this like:

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QPainter overlayPainter(&overlayClusters);
QPixmap pixmap = QPixmap::fromImage(maskForegroundByUser);
overlayPainter.setClipRegion(QRegion(pixmap));
overlayPainter.fillRect(overlayClusters.rect(),brush);
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but i can't create a QRegion from a QPixmap.

Can someone help me?

//EDIT
This solution works and has good performance:
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QPainter overlayPainter(&image);
QBitmap bitmap = QBitmap::fromImage(mask); //mask is a QImage with the format Mono
QRegion regionMask(bitmap);
overlayPainter.setClipRegion(regionMask);
overlayPainter.setCompositionMode(QPainter::CompositionMode_SourceOver);
QBrush brush(Qt::blue,Qt::SolidPattern);
overlayPainter.fillRect(image.rect(),brush);
@
Greetings