C++ over Qt : Controlling transparency of Labels and Buttons

问题

Well, I was again trying my hands on a Linux GUI app on Qt Creator, I added couple of images in a Qt resource file of my project. And I tried to have a nice background in my main window and other windows and dialogs. I was using from the stylesheets option (no coding).

I am unable to set the transparency level of labels and pushbuttons. Any ideas on how to do it from Qt creator GUI itself ???
!I am attaching a snap of how my application looks.

回答1:

You can set transparency of QLabel or QPushbutton by setting the stylesheet :

ui->label->setStyleSheet("background-color: rgba(255, 255, 255, 0);");
ui->button->setStyleSheet("background-color: rgba(255, 255, 255, 0);");

You can also add background-color: rgba(255, 255, 255, 0); to the styleSheet property of the widget in the designer.

The fourth parameter is alpha. You can also have semi-transparent widgets by setting alpha to some value more than zero :

ui->button->setStyleSheet("background-color: rgba(255, 255, 255, 50);");

回答2:

There is the property "Window opacity" in the QWidget section of the ui element property (bottom right in qtDesigner view). By default it is 1.0 (completely opaque).

It is also available programmatically

回答3:

This worked For me:

this->setWindowOpacity(0.35);
this->setAttribute(Qt::WA_TranslucentBackground, false);
this->setStyleSheet("background-color: yellow;");

回答4:

Not from GUI, but still can be useful for someone:

    auto effect = new QGraphicsOpacityEffect(this);
    effect->setOpacity(0.5);
    yourWidget->setGraphicsEffect(effect);
    yourWidget->setAutoFillBackground(true);

Stolen from here.

来源：https://stackoverflow.com/questions/23948453/c-over-qt-controlling-transparency-of-labels-and-buttons