Freetype has a compile-time feature that, when enabled, rewrites the
font names of PCF fonts to include the foundry and wide status of the
font in order to disambiguate the various versions of fonts all named
"Fixed".
That option is enabled by default in some linux distributions but not
all; it's not enabled in Fedora, for example.
When that feature is enabled it causes problems for the Terminus font as
the PCF version of the fonts are no longer resolvable via the simple
"Terminus" name but via "xos4 Terminus" instead.
wezterm builds its own version of freetype (for consistency and cross
platform support reasons), and is unaware of the choice used by the
distro.
The result of that is that fontconfig may see PCF fonts as having
different font names than how wezterm sees them.
A concrete problem is on such a system, when requesting "xos4 Terminus",
fontconfig will present a match with that name, but when wezterm opens
the font and sees that it has name "Terminus" (because of the difference
in this feature in the freetype libraries in use), wezterm will reject
that match.
This commit enables that option in the freetype library and adds a
wezterm config level option (freetype_pcf_long_family_names) that can be
used to control the underlying pcf font driver configuration.
The upshot of this is that this commit doesn't change any default
behavior, but allows users of those systems to set
`freetype_pcf_long_family_names = true` to turn that behavior on.
My personal opinion on this is that users probably shouldn't use this if
they can avoid it (and PCF fonts in general), and instead install the
OTB version of the Terminus font, which doesn't have this legacy baggage
associated with it!
refs: https://github.com/wez/wezterm/issues/2100
By default, freetype doesn't include error strings and FT_Error_String
will always return NULL. Turn on the compile time option that makes
this function useful!
This commit more cleanly separates the load from the render flags,
and fixes up the render call; at some point this got messed up such
that we'd never end up with freetype returning subpixel format data
(LCD) and instead we'd only ever get grayscale data.
With that fixed, it's apparent that the colorization of the glyph
data was wonky in the shader so this commit also cleans this up.
refs: #320
refs: #121
Forgetting to update the submodules is a commonly reported build
issue with an obscure error message:
```
CMake Error: The source directory "/home/USER/wezterm/target/debug/build/freetype-430fe24cb64c561c/out/zlib-src/zlib" does not appear to contain CMakeLists.txt.
```
this teaches the build.rs machinery to run the submodule update
if it looks like it is needed.
This is primarily for macos where the default freetype
installation is unable to render color emoji, but should also
help make things more consistent across the various platforms.
It's a little bit awkward on linux because the font-loader crate
pulls in the now-conflicting servo-font* crates. I've disabled
font-loader on linux systems; it's just calling fontconfig under
the covers anyway.
