How can I make my app ignore window's "HIGH DPI SCALING"?

[Curtwagner1984]

Thank you! For some reason I assumed this needs to be done after.

It's like this now:

    QApplication::setAttribute(Qt::AA_DisableHighDpiScaling); // Disable DPI support

    QApplication a(argc, argv);


    MainWindow w;
    w.showMaximized();
    
    return a.exec();

But it doesn't really seem to have an effect.

This is how it looks on a display with 100% scaling and this is how it looks on a display with 150% scaling

[JKSH]

@Curtwagner1984 said in How can I make my app ignore window's "HIGH DPI SCALING"?:

it doesn't really seem to have an effect.

Try running your app in "DPI Unaware" mode: https://doc.qt.io/qt-5/highdpi.html#migrate-existing-applications

[Curtwagner1984]

Thanks,
I made a file named qt.conf with the line

<application> -platform windows:dpiawareness=0

And put it in the the folder of the executable. Nothing changed.

Is this correct? Should application be the name of the application?

[JKSH]

@Curtwagner1984 said in How can I make my app ignore window's "HIGH DPI SCALING"?:

I made a file named qt.conf with the line

<application> -platform windows:dpiawareness=0

Those are command line arguments. You pass the extra arguments while launching your .exe from the Command Prompt .

[Curtwagner1984]

Thank you! This works!
Is there a way to set it up in the application itself, without the need to provide extra command line arguments?

[J.Hilk]

@Curtwagner1984
good old putenv, probably

https://www.cprogramming.com/fod/putenv.html

[JonB]

@J-Hilk
I looked at this. What environment variable name (and value) are you proposing for -platform windows:dpiawareness=0, I could not see that it worked this way??

[J.Hilk]

@JonB admittedly
the official way to do it, is apparently the creation and deployment of a qt.conf file, same level as the executable with this content:

[Platforms]
WindowsArguments = dpiawareness=0

that said:

qputenv("dpiawareness", "0"); or qputenv("windows:dpiawareness", "0");

I'm unsure, I'm not using it often enough :D

[JonB]

@J-Hilk said in How can I make my app ignore window's "HIGH DPI SCALING"?:

qputenv("dpiawareness", "0"); or qputenv("windows:dpiawareness", "0");
I'm unsure, I'm not using it often enough :D

There is/I can see no evidence that a Qt program would recognise either of these proposed environment variable names. Unless you can see where it says it does.... I see only the command line or qt.conf file approaches so far.

[Curtwagner1984]

@J-Hilk said in How can I make my app ignore window's "HIGH DPI SCALING"?:

[Platforms]
WindowsArguments = dpiawareness=0

Thank you! I tried to used this before but I've put incorrect syntax in this file. This works.

[arunkannan]

@Curtwagner1984 @JonB @J-Hilk @JKSH
I used Python PyQt5-5.15 for my application
I have guimain.exe and panelgui.ui files . Made qt.conf file
But when I change windows scaling to 125% or 150% the text fonts and other ui widgets get messed up...how to make it work i.e disable windows scaling for application

[Violet Giraffe]

In Qt 6 you can override the scale factor with the QT_SCALE_FACTOR env variable, but there is a problem: it doesn't set the factor to your value, it multiplies it. For example, if the system has 150% and you want 100%, you need to set QT_SCALE_FACTOR to 0.666667 (and even then it might not end up exactly 1.0 but rather 1.0001).

Is this intentional? There is a number of problems resulting from this multiplicative behavior, the primary one being when the application is moved between screens with different scale factors. I want to have 1.0 everywhere, not 0.66!

Also, -platform windows:dpiawareness=0 DOES NOT WORK!
Or, rather, it does the wrong thing. It disables too much, devicePixelRatio() reports 1.0 but the window is stretched and blurry.

[Violet Giraffe]

Found the proper option: QT_ENABLE_HIGHDPI_SCALING=0.