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mirror of https://github.com/wez/wezterm.git synced 2024-12-24 13:52:55 +03:00
wezterm/wezterm-font
Wez Furlong 98f289f511 wezterm-font: improve fallback font scaling
Use the scaling factor between the font metrics for the base font
and those of the fallback font selected for a given glyph.

The scenario is this: the base font is typically the first one selected
from the font configuration.  There may be multiple fallback fonts that
are different sizes; for instance, the Font Awesome font has glyphs that
are square in aspect and are thus about twice the width of a typical
textual monospace font.  Similarly, Noto Color Emoji is another square
font but that has a single set of bitmap strikes at a fixed 128 px
square.

The shaper returns advance metrics in the scale of the containing font,
and the rasterizer will target the supplied size and dpi.

We need to scale these to match the base metrics.

Previously we used a crude heuristic to decide whether to scale,
and that happened to work for Noto Color Emoji but not for Font Awesome,
whose metrics were just inside the bounds of the heuristic.

This commit allows retrieving the metrics for a given font_idx so
that we can compute the correct scale factor without any heuristics,
and applies that to the rasterized glyph.

refs: https://github.com/wez/wezterm/issues/342
2020-11-23 16:59:30 -08:00
..
src wezterm-font: improve fallback font scaling 2020-11-23 16:59:30 -08:00
Cargo.toml wezterm: improve shaping of emoji 2020-11-23 13:45:38 -08:00