Implementing fullscreen mode - frameless window that hides the taskbar

[NetZwerg]

Try adding

QMainWindow::setWindowFlags(Qt::FramelessWindowHint);

[Violet Giraffe]

Finally got time to return to this task.
If I do as you suggested, the window just disappears both from screen and from the taskbar (no button, which is typical for frameless windows).

UPDATE: Turns out, a mere showFullScreen call does the trick. What got me confused previously when I tried was that there's a ~1 second delay between the window maximizing and the taskbar disappearing.
Now the only problem I have is how to restore the original size and position of the window. Guess I'm gonna have to use the saveGeometry / restoreGeometry methods.

[A Former User]

Hi, using the following function works for me:
void QWindow::setWindowState(Qt::WindowState state) with state Qt::WindowFullScreen.

[Violet Giraffe]

That has the same effect as showFullscreen. Perhaps, the implementation is the same. I find showFullscreen much more neat.

For restoring, I call QRect savedGeometry = geometry() before showFullscreen, and then when I need to get back to a regular window:

showNormal();
setGeometry(_nonFullscreenWindowGeometry);
raise();
activateWindow();

Not sure if raise and activateWindow are necessary, it's just a code snippet I see in many different Qt projects that's called when window state changes. Could be a fix for some very old Qt bug that's been fixed long ago, for all I know.

[A Former User]

@Violet-Giraffe Yes, it has the same effect. You said you want to restore the window's previous geometry: You can just read the current state with Qt::WindowState QWindow::windowState() const and restore it when you need to. This also automatically restores the previous geometry.

[Violet Giraffe]

@Wieland said:

This also automatically restores the previous geometry.

That's neat! setWindowState(windowState() & ~Qt::WindowFullScreen) works like charm (at least on Windows 7), no need for any additional member variables.
Thanks.

[Chris Kawa]

Also note there's a showNormal()method that does the same as tinkering with windows states.
There are basically 4 methods for setting the state: showNormal(), showMaximized(), showMinimized() and showFullScreen(). They might be more convenient than tracking the state flags, depending on your need.

[Violet Giraffe]

showNormal alone doesn't restore the original geometry, it just exits the full screen mode.

[Chris Kawa]

That's... weird. The implementation is basically the same, i.e.

void QWidget::showNormal()
{
   ensurePolished();
   setWindowState(windowState() & ~(Qt::WindowMinimized | Qt::WindowMaximized | Qt::WindowFullScreen));
   setVisible(true);
}

I wonder if that's some bug then?

[Violet Giraffe]

Re-checked and confirmed: showNormal works properly in conjunction with showFullScreen.