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I have a QWidget that contains a QPixmap and a QComboxBox in its Layout. I would like to set the background of the widget transparent (but I want to show the QPixmap and the QComboBox normally). How do I do that?

NoDataDumpNoContribution
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Vincent
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2 Answers2

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You can use the attribute 

widget->setAttribute(Qt::WA_NoSystemBackground);

Qt documentation :

Indicates that the widget has no background, i.e. when the widget receives paint events, the background is not automatically repainted. Note: Unlike WA_OpaquePaintEvent, newly exposed areas are never filled with the background (e.g., after showing a window for the first time the user can see "through" it until the application processes the paint events). This flag is set or cleared by the widget's author.

MSA
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It is all well-explained in QWidget documentation: http://doc.qt.io/qt-5/qwidget.html#transparency-and-double-buffering

ypnos
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    both links are dead, which is the reason why answers should not just contain links but the relevant information itself. – hochl Aug 19 '15 at 09:19
  • I agree that is a problem. However the information asked for here is not very specific and the documentation is explaining it very well. No need to repeat it here. I updated the link to the documentation. – ypnos Aug 19 '15 at 15:33
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    The explanation does not really help or work, though. I added a QGraphicsView to a transparent widget, but despite setting the graphics view's Qt::WA_PaintOnScreen attribute, it remains to appear as transparent as the widget it is in. – TheSHEEEP Oct 11 '16 at 06:53