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Code Issues Projects Releases Wiki Activity

fonts: handle bitmap-only fonts better

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terminus-bold.otb reports 0 height!

Detect and force that case to go through the bitmap strike loading
code path.

Improve the size selection heuristic for bitmap strikes: previously,
we would just pick the largest bitmap and allow it to be scaled down,
which was OK for emoji fonts that just had 128px square glyphs, but
is not ok for pre-rendered pixel strikes like terminus.

Note that IncreaseFontSize works in terms of percentages only,
so using a font like this may have "gaps" when ctrl-+ or - to change
the font size.

refs: https://github.com/wez/wezterm/issues/560
This commit is contained in:
Wez Furlong 2021-03-20 12:52:20 -07:00
parent d62d2a5133
commit 1cf335cb45
2 changed files with 52 additions and 16 deletions
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1
docs/changelog.md
View File

@ -12,6 +12,7 @@ brief notes about them may accumulate here.
* Fixed: 100% CPU due to spurious resize events generated by herbstluftwm. [#557](https://github.com/wez/wezterm/issues/557)
* Fixed: improved conformance with xterm for keys like CTRL-6 and CTRL-/. [#556](https://github.com/wez/wezterm/discussions/556)
* Fixed: detection and handling of fonts such as terminus-bold.otb that contain only bitmap strikes. [#560](https://github.com/wez/wezterm/issues/560)
### 20210314-114017-04b7cedd

67
wezterm-font/src/ftwrap.rs
View File

@ -89,7 +89,14 @@ impl Face {
}
}
log::debug!("set_char_size computing {} dpi={}", point_size, dpi);
let pixel_height = point_size * dpi as f64 / 72.0;
log::debug!(
"set_char_size computing {} dpi={} (pixel height={})",
point_size,
dpi,
pixel_height
);
// Scaling before truncating to integer minimizes the chances of hitting
// the fallback code for set_pixel_sizes below.
let size = (point_size * 64.0) as FT_F26Dot6;
@ -100,6 +107,8 @@ impl Face {
self.cell_metrics()
}
Err(err) => {
log::debug!("set_char_size: {:?}, will inspect strikes", err);
let sizes = unsafe {
let rec = &(*self.face);
std::slice::from_raw_parts(rec.available_sizes, rec.num_fixed_sizes as usize)
@ -107,24 +116,42 @@ impl Face {
if sizes.is_empty() {
return Err(err);
}
// Find the best matching size.
// We just take the biggest.
let mut best = 0;
let mut best_size = 0;
let mut cell_width = 0;
let mut cell_height = 0;
// Find the best matching size; we look for the strike whose height
// is closest to the desired size.
struct Best {
idx: usize,
distance: usize,
height: i16,
width: i16,
}
let mut best: Option<Best> = None;
for (idx, info) in sizes.iter().enumerate() {
let size = best_size.max(info.height);
if size > best_size {
best = idx;
best_size = size;
cell_width = info.width;
cell_height = info.height;
log::debug!("idx={} info={:?}", idx, info);
let distance = (info.height - (pixel_height as i16)).abs() as usize;
let candidate = Best {
idx,
distance,
height: info.height,
width: info.width,
};
match best.take() {
Some(existing) => {
best.replace(if candidate.distance < existing.distance {
candidate
} else {
existing
});
}
None => {
best.replace(candidate);
}
}
}
self.select_size(best)?;
(f64::from(cell_width), f64::from(cell_height))
let best = best.unwrap();
self.select_size(best.idx)?;
(f64::from(best.width), f64::from(best.height))
}
};
@ -157,7 +184,15 @@ impl Face {
},
(),
)
.context("FT_Set_Char_Size")
.context("FT_Set_Char_Size")?;
unsafe {
if (*self.face).height == 0 {
anyhow::bail!("font has 0 height, fallback to bitmaps");
}
}
Ok(())
}
fn select_size(&mut self, idx: usize) -> anyhow::Result<()> {