Related to #1768 but doesn't fix it properly.
This is a temporary hack to avoid some issues with fonts that have mixed
color/non-color glyphs. If there are mixed presentations and the font
does not have emoji codepoints, then we assume it is text. This fixes
the typical scenarios.
This is not a long term solution. A proper long term solution is to
detect this scenario and on a per-glyph basis handle colorization (or
the lack thereof) correctly. It looks like to do this we'll have to
parse some font tables which is considerably more work so I wanted to do
this first.
Fixes#1795
This only affected CoreText. When testing with Freetype the
strikethroughs looked correct for fonts with and without leading
metrics.
This commit adjusts our strikethrough position for fonts that have a
leading metric set to better center it. Previously, we centered the
position _including_ the leading value. The leading value is blank, so
we must center it excluding that value.
Fixes#895
Every loaded font face calculates metrics for itself. One of the
important metrics is the baseline to "sit" the glyph on top of. Prior to
this commit, each rasterized glyph would sit on its own calculated
baseline. However, this leads to off-center rendering when the font
being rasterized isn't the font that defines the terminal grid.
This commit passes in the font metrics for the font defining the
terminal grid to all font rasterization requests. This can then be used
by non-primary fonts to sit the glyph according to the primary grid.
This maybe is a robust way to get Monaspace fonts working.
Previously, we used leading as part of the calculation in cell height. I
don't remember why. It appears most popular monospace fonts (Fira Code,
Berkeley Mono, JetBrains Mono, Monaco are the few I tested) have a value
of 0 for leading, so this has no effect. But some fonts like Monaspace
have a non-zero (positive) value, resulting in overly large cell
heights.
The issue is that we simply add leading to the height, without modifying
ascent. Normally this is what you want (normal typesetting) but for
terminals, we're trying to set text centered vertically in equally
spaced grid cells. For this, we want to split the leading between the
top and bottom.
