How to fix the blanked out windows in fullscreen mode?

lachdanan

Hi,

I am having a similar issue to this guy:
https://stackoverflow.com/questions/60854878/issue-with-blanking-screen-when-running-qt-application-in-fullscreen-mode

I have an app that uses OpenGL windows, so when I put this application in fullscreen mode, it blanks out all windows, showing no controls, only the individual windows. It looks a bit like this but not exactly the same (my 3d viewport also seem to blank out)
https://i.imgur.com/tIUu24N.png

I filed a bug for the app itself and the devs said they did change some windowing stuff. Before this it was working. So I am wondering if it was due to this or some intel drivers issue. Anything I can try as a workaround to make sure this doesn't happen?

Thanks in advance.

SGaist

Hi,

Do you have any way to reproduce that ?
Which version of Qt are you using ?
Which platform are you running your application on ?
What is your setup ?

lachdanan

Hi,

I am able to reproduce it using the code I have and the same code when I gave it to others it does that too.

Actually my code is just doing this:

window = hou.ui.mainQtWindow()
   if window.isFullScreen():
        window.showMaximized()
    else:
        window.showFullScreen()

But it has to be done on this software called Houdini FX/Indie: https://www.sidefx.com/download/

I know it happens on windows, other platforms I didnt try.

I am not sure how to check the Qt version from Pyside2, but I think it's v5.

My setup is basically running the above code after the app I posted above is launched.

Christian Ehrlicher

Please take a look at https://doc.qt.io/qt-5/windows-issues.html#fullscreen-opengl-based-windows

lachdanan

Thanks I saw this one but I dont know how to call that function from pyside2:
setHasBorderInFullScreen

Also I dont know what the other guy in my OP is suggested as his own workaround:
"As a workaround I tried to placed a hidden (opaque) mini window (0x0px) using Qt::WindowStaysOnTopHint - that worked. If anyone knows a better solution please let us know. Thanks."

Lastly this app used to work in fullscreen mode, I recorded an entire tutorial series using it. But later on in their new version they told me they made some windowing changes which might cause it but I dont know what could cause it.

They said they might look at it, but I need to find a solution as they might not fix it at all.

lachdanan

Any ideas on this issue?

Another thing is, if I try to record the screen with any app, the software in question looks perfectly fine.

Even though to me everything is blanked out. Like they flicker and blank out. If I do, Alt+Tab, it comes back to normal, then happens again when the app is in focus, etc.

So I assume this is some sort of drivers issue? I tried with both Quadro drivers and Intel drivers. My laptop has both.

lachdanan

On my new laptop on win 10 this didnt happen. I recently upgraded to win 11, and this issue started happening again.

Then I noticed because I use an external display, and my laptop display, this time I disabled laptop display to only use my external display. It was doing it because of this for this case.

I enabled laptop display to extend the desktop and now it doesnt happen. I think the issue is, from what I read in a similar topic on stackoverflow is that if the app is fullscreen, qt or whatever is causing these issues creating display problems.

I noticed the same issue even if I manually set my window fullscreen by move and resize and removing the title bar. So it's not just the call to fullscreen, even setMaximize also do the same.

Not sure what else can be done to actually fix this.

mzimmers

I know this topic is quite old, but as it is unsolved, and I just started running into a similar problem, I thought I'd revive it.

When I try to use:

ApplicationWindow {
    id: mainWindow
    visible: true
    visibility: Window.FullScreen // this line is problematic.
    ...

I get problems. On Windows 11, the screen goes blank and the application hangs. On Ubuntu 22.04, the same thing occurs (the only difference is that the OS detects the hang and asks if I want to kill the program).

I'm ultimately going to need this on an embedded platform running Yocto, but I first hoped to getting it working on a desktop.

I notice that the solution in @Christian-Ehrlicher's link above is obsolescent, as QWindowsWindowFunctions doesn't exist in Qt 6, but I'm not sure that matters, as that isn't exactly the same problem as I'm seeing.

Anyone have any ideas? My online searches haven't revealed much that is current on this.

Thanks...

JoeCFD

This setting works well in Qt5. Qt6 may be different. There is one example here.
https://doc.qt.io/qt-6/qml-qtquick-window.html#visibility-prop

mzimmers

@JoeCFD thanks...it does work with Qt 6.5.3. Evidently, there's something in my application that is the problem. I'll chase it down, and if the answer is worthwhile, I'll post about it.