Set transparency without setting background color

[cdonts]

You can subclass, reimplement the paint event and use QPainter::setOpacity() before calling the base class implementation.

QStylePainter p(this);
p.setOpacity(0.1)M
QStyleOptionButton option;
initStyleOption(&option);
p.drawControl(QStyle::CE_PushButton, option);

QStylePainter p(this);
p.setOpacity(0.1)M
QStyleOptionButton option;
initStyleOption(&option);
p.drawControl(QStyle::CE_PushButton, option);

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Thanks! This works. But, that is the unique way to set transparency to a widget? Each widget I have to set some transparency I need to subclass it and replace the paintEvent function?

Or you can use QWidget::setWindowOpacity on the top level window

That's for the window or for any widget? It didn't work for me. Thanks.

[wysota]

QStylePainter p(this);
p.setOpacity(0.1)M
QStyleOptionButton option;
initStyleOption(&option);
p.drawControl(QStyle::CE_PushButton, option);

QStylePainter p(this);
p.setOpacity(0.1)M
QStyleOptionButton option;
initStyleOption(&option);
p.drawControl(QStyle::CE_PushButton, option);

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Thanks! This works.

I meant more like:

class TranslucentButton : public QPushButton {
// ...
protected:
  void paintEvent(QPaintEvent *pe) {
    QPainter p(this);
    p.setOpacity(0.7);
    QPushButton::paintEvent(pe);
  }
};

class TranslucentButton : public QPushButton {
// ...
protected:
  void paintEvent(QPaintEvent *pe) {
    QPainter p(this);
    p.setOpacity(0.7);
    QPushButton::paintEvent(pe);
  }
};

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If it works, of course...

But, that is the unique way to set transparency to a widget?

You can also apply a QGraphicsOpacityEffect to a widget that will provide the transparency.

[cdonts]

I meant more like:

class TranslucentButton : public QPushButton {
// ...
protected:
  void paintEvent(QPaintEvent *pe) {
    QPainter p(this);
    p.setOpacity(0.7);
    QPushButton::paintEvent(pe);
  }
};

class TranslucentButton : public QPushButton {
// ...
protected:
  void paintEvent(QPaintEvent *pe) {
    QPainter p(this);
    p.setOpacity(0.7);
    QPushButton::paintEvent(pe);
  }
};

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If it works, of course...


You can also apply a QGraphicsOpacityEffect to a widget that will provide the transparency.

Fantastic! Thank you very much!

[aamer4yu]

That's for the window or for any widget? It didn't work for me. Thanks.

It is for top level window.
in main.cpp, just use setWindowOpacity() on the top level window you create.

[cdonts]

It is for top level window.
in main.cpp, just use setWindowOpacity() on the top level window you create.

I'm not using C++. It works. Thank you.