transparent widget

[hijinks]

I have a little game I'm making in qt 4.1. Right now I'm doing this part while on a windows XP machine. I have a mainwindow which basicall gets created like this



GUI::GUI() {
// setting the max/min size
setMinimumSize(350, 450);
setMaximumSize(350, 450);

// filling the background with white
//setAutoFillBackground(true);
QPalette palette;
palette.setColor(QPalette::Background, Qt::white);
setPalette(palette);


Now when i start a new game I want to overlay like a black widget that has like a 50% transparency so you can still see the little gameboard and such. I am having no such luck getting another widget to be transparent over my mainwindow

Here is my latest attempt at trying to get it to work



QWidget *blackBG = new QWidget(this);
blackBG->setGeometry(0,0,350,450);
blackBG->setAutoFillBackground(true);
blackBG->setPalette(QPalette(QPalette::Background, Qt::black));
blackBG->setWindowOpacity(.5);
blackBG->show();



any help? thanks!

[axeljaeger]

SetWindowOpacity only works for topLevelWindows as slightly mentioned in the docs:

http://doc.trolltech.com/4.1/qwidget.html#windowOpacity-prop

They use the term window instead of widget.

You will have to draw the semi transparent layer in the paintEvent of your widget beneath the layer.

[Mike]

Scott Collins talked about this in his blog. Did you try this?

http://scottcollins.net/blog/2005/10/transparent-backgrounds-in-qt.html