Window scale_factor_override() doesn't affect cursor position

[AidanBlair]

Bevy version

0.5

Operating system & version

Windows 10

What you did

Because my screen has a high DPI and scales applications to 125%, I created a window with scale_factor_override: Some(1.0). I also added a button in the middle of the window.

What you expected to happen

The window will display at 100% scale (rather than 125%) and the cursor's position will update accordingly.

What actually happened

While the window did display correctly at 100% scale, the cursor position seems to still behave as if it was scaled to 125%. To click on the button, I had to click above and to the right of the button, and when I printed out the cursor position the top right corner's position was (480, 360) rather than the actual size of the window, (640, 480).

[AidanBlair]

I've attached an example program (I couldn't upload a .rs file so I copied it to a .txt file). If you don't have a font installed you can tell when the button is selected by the colour changing. Also, I have it printing out the cursor's location, to show that it doesn't match up with the actual size of the window.

scaling_example.txt

[alice-i-cecile]

Doing a bit of digging, this issue seems like it might have promising breadcrumbs from winit, our upstream dependency for windowing: rust-windowing/winit#1491

Now, let's track how cursor position is set...

update_cursor_position_from_backend seems to be the function in question. Let's see where that's called: here, in the bevy_winit module.

We have access to the scale factor information in that function already; it looks like it's just a matter of adding a multiplication step just above L315 (and adding some tests).