How to draw a QPixmap with transparency

qt transparent qpainter qpixmap
laurent picture laurent · Aug 8, 2011 · Viewed 9k times · Source

I've got a QPixmap and I would like to draw it on a QWidget. However, I would like to make it 50% transparent so that the background can be seen below. How can I do that?

Answer

Martin Beckett picture Martin Beckett · Aug 8, 2011

You set the compositionmode in the QPainter and then either use a mask to define which bits of the iage are transparent or use QImage::Format_ARGB32_Premultiplied type for the image with the alpha channel set.

See the example http://doc.qt.io/archives/4.6/demos-composition.html

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