QWidget transparent background (but not the children)

问题

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?

回答1:

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

回答2:

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.

来源：https://stackoverflow.com/questions/11688750/qwidget-transparent-background-but-not-the-children