Question

How can I draw a selection rectangle on my screen with Qt in X11?
I want to be able to drag a rectangle on my screen (outside of the application) and then save the whole rectangle.

Thanks in advance.

Answer 1

Part of the solution will involve using the grabWindow() function of QPixmap like so:

QPixmap::grabWindow(QApplication::desktop()->winId());

Qt has an example program for this here.

There rest of the solution, drawing the area to grab, can probably be achieved by either using a full screen transparent window to render a mouse drawn rectangle and then taking the section it outlines from the grabbed desktop image or using a full screen window with the entire grabbed screen painted on it.