PyQt5 - possible to recreate the application main window at runtime?

neo-mashiro

Hi, I have a PyQt application which runs on Linux with a dual-monitor setup. I can move the application between two screens, but one of them has a high DPI 4K resolution so the text/labels/icons appear very small.

After reading the documentation, I tried setting the QT_SCALE_FACTOR environment variable, and that works fine on my machine. With different values, the entire application window gets scaled up/down accordingly which is exactly what I want. However, QT_SCALE_FACTOR seems to be only read once at startup, changing it at runtime has no effect. It's a bit annoying that I have to set this value before launching the app or do a complete restart.

I wonder if Qt provides a way to dynamically zoom in/out the entire application main window at runtime. That would make life much easier. All that I want to change at runtime is the rendering aspect of things so that widgets are scaled up/down, ideally I can just reload/refresh the UI window without changing any application data.

I know many apps like VSCode support this feature because web technologies like Electron make it very easy to implement, but it seems to be much more complicated in Qt?

SGaist

I meant it's achieved internally so you don't have to do anything special unless you are doing your own rendering.
QScreen would be of interest.

SGaist

Hi,

Might not be the answer you are looking for but Qt 6 should have better handling for that use case.

neo-mashiro

@SGaist Thanks, that's really good to know as I'm thinking about upgrading to Qt 6. Any details about how Qt 6 will be able to handle this or are there examples or documentation I can read and follow?

SGaist

I meant it's achieved internally so you don't have to do anything special unless you are doing your own rendering.
QScreen would be of interest.