[Feature Request]: Option to prioritize consistent vertical pixel height for integer scaling

[taco94]

Description

Add a checkbox to prioritize consistent vertical pixel height while using integer scaling and make it work similar to PCSX2's Window Size scaling multiplier in the View menu.

Basically if the current integer scaler multiplies the internal resolution and then stretches it vertically to fit the aspect ratio, this would instead stretch the image horizontally to preserve the vertical height of the image.

Reason

When using integer scaling, horizontal pixels are a consistent width, but vertical pixels are an inconsistent height.

This causes issues with crt shaders such as crt-royale for ReShade which expects vertical pixels with the same height. Currently it is not possible to get a scanline shader that relies on integer scaling to match up perfectly with the vertical pixels due to the alternating height.

Example screenshot from Jak and Daxter 1:

This is a screenshot of the output on a 4k monitor with deinterlacing turned off with a pixel grid overlaid from photoshop. The horizontal pixels are consistently 5 pixels wide, but the vertical pixels alternate between 8 and 9 pixels high.

Examples

A perfect example is the current option in PCSX2 under View -> Window Size. With integer scaling turned off, the vertical pixels are consistently 8 pixels high while the horizontal pixels are uneven between 4 and 5 pixels, which would be the intended behavior for the proposed option.

Example: