Fix some monospace fonts spacing being non-monospace

[alphaqu]

On fonts like Jetbrains Mono the rounding to the closest pixel after every glyph made the spacing between the characters non-monospace. This fixes that issue by rounding the glyph location instead of the cursor x position which affects the future characters in a non-expected way.

[emilk]

I tried this out with the default font with pixels_per_point = 1.15.

Before:

After:

The new code produces some bad kerning in many places:

[alphaqu]

A possible fix might be to only apply this fix on monospace fonts as those are the ones which need this fix to be quote on quote "monospaced".

[alphaqu]

Another solution to this problem is to provide the glyph width correctly in the first place. Rendering rounds the glyph_width which makes it be different than the application (for example a cursor drawer). Just rounding the glyph_width on the getter makes the behavior consistent across the codebase.

I originally missjudged my issue. I thought the drawer was messing up the spacings but it was just using a different glyph width to fix the spacing.

[parasyte]

@alphaqu could you try the patch in #2490? I don't have an app using Jetbrains Mono, and I'm not exactly sure what I should be looking for to compare between actual and expected rasterization because there are no screenshots here.

The linked patch may address the issue you had if your pixels_per_point is greater than 1.0. (I.e. on a high DPI display.)