Issues rendering italic and underlines

[nree]

Sorry for poor job on the pic but:
Top line is fvim
Bottom line is cmder / conemu running vim (nvim)

This is Windows 10, using same font (SF Mono), same vim config, same wsl / neovim.

• Cuts off italic last letter
• Cuts off italic height of some letters (g in settings)
• Underlines swiggles aren't connected, has a dotted look to them and look poor quality

I tried different fonts:

• Consolas: italics ok has minor clipping except for underlines
• Source Code Pro: italics slightly clips but not bad at all, underlines still bad
• Fira Code: very bad clipping on italics and underline

I've tested fonts on other apps: Cmder (conemu) in the picture, tested with visual studio code, and emacs.

[yatli]

interesting. looks like the font measurement function calcs off.
for height, you can workaround this by setting :FVimFontLineHeight (for example, :FVimFontLineHeight '+1.0')

[yatli]

The horizontal clipping is weird. fvim conducts backward rendering so if the line comes in, later glyphs will be drawn first.

[yatli]

The horizontal clipping is repro'ed and I think I've pinpointed the issue:

fvim/ui.fs

Lines 342 to 348 in 4e77a9b

	let RenderText (ctx: IDrawingContextImpl, region: Rect, scale: float, fg: SKPaint, bg: SKPaint, sp: SKPaint, underline: bool, undercurl: bool, text: string, shaper: SKShaper ValueOption) =
	ctx.PushClip(region)
	// DrawText accepts the coordinate of the baseline.
	// h = [padding space 1] + above baseline | below baseline + [padding space 2]
	let h = region.Bottom - region.Y
	// total_padding = padding space 1 + padding space 2

note that only the last glyph of an italic span gets clipped.

[yatli]

@nree I'll push out a release soon. it should be fixed

[nree]

Looks very very good now! Some of the best I've seen 😁

Regarding line height issue: (italic g, y + underline) I noticed something new... it actually renders good (first render). But then on re-renders after it will clip. Is this a bug? So it seems possible to render these height issues good, just something in the render clips them after. Should I open new issue about this? Opening new issue