There are three slants that are broadly recognized; normal, italic and
oblique. Prior to this commit, we only considered normal or italic.
This is mostly a mechanical change to replace the boolean with the enum,
and rename the field from `italic` to `slant`.
For the sake of backwards compatibility with existing configs, the lua
helpers for working with fonts continue to accept boolean italic values
and rewrite them to the equivalent slant value.
refs: #1646
Resolves a little bit of the awkward duplication of color types
between some of the crates by factoring them a little bit better.
This is prep for allowing specifying alpha for some colors
in the config.
For a sequence like `e U+20d7` the intent is to render the `e` with
a vector arrow over the top.
This is typically implemented by fonts as an `e` followed by the
vector glyph (or vice versa), where either one of those may have
a zero advance so that the two elements are combined.
There were two problems here:
* During shaping we'd see the zero advance and assume that the entry
was useless and skip it
* During rendering, if we didn't think it had any cell width, we'd
not render it
Cursoring through that particular sequence can hide the vector
mark if the cursor is set to the default block cursor due to annoyances
in how the block cursor is rendered (it changes the fg color to match
the bg, but for elements outside where we think the cursor is, this
makes those elements invisible).
refs: https://github.com/wez/wezterm/issues/1617
This is a more robust approach; we make a separate pass to figure
out information about the (harfbuzz) cluster for a sequence of glyphs,
and then map that sequence back to the original cell sequence, and
from there compute the total cell width for the run, then distribute
the glyphs across the run.
This should yield more sane results for bidi.
Fixup the x-position math; it was still wonky despite the
efforts in 5f2c905db8 and
af92265ffb
refs: #1570
refs: #1607
refs: #1563
This allows unicode_version to be respected again when rendering.
The updated emoji-presentation.sh script now highlights this slightly
better by putting `.` characters after the emoji; unicode version 14
emoji presentation will show the `.` in the 3rd column, while earlier
versions will show it in the 2nd column for glyphs that are sensitive
to the version.
refs: #1607
refs: #1563
This commit is larger than it appears to due fanout from threading
through bidi parameters. The main changes are:
* When clustering cells, add an additional phase to resolve embedding
levels and further sub-divide a cluster based on the resolved bidi
runs; this is where we get the direction for a run and this needs
to be passed through to the shaper.
* When doing bidi, the forced cluster boundary hack that we use to
de-ligature when cursoring through text needs to be disabled,
otherwise the cursor appears to push/rotate the text in that
cluster when moving through it! We'll need to find a different
way to handle shading the cursor that eliminates the original
cursor/ligature/black issue.
* In the shaper, the logic for coalescing unresolved runs for font
fallback assumed LTR and needed to be adjusted to cluster RTL.
That meant also computing a little index of codepoint lengths.
* Added `experimental_bidi` boolean option that defaults to false.
When enabled, it activates the bidi processing phase in clustering
with a strong hint that the paragraph is LTR.
This implementation is incomplete and/or wrong for a number of cases:
* The config option should probably allow specifying the paragraph
direction hint to use by default.
* https://terminal-wg.pages.freedesktop.org/bidi/recommendation/paragraphs.html
recommends that bidi be applied to logical lines, not physical
lines (or really: ranges within physical lines) that we're doing
at the moment
* The paragraph direction hint should be overridden by cell attributes
and other escapes; see 85a6b178cf
and probably others.
However, as of this commit, if you `experimental_bidi=true` then
```
echo This is RTL -> عربي فارسی bidi
```
(that text was sourced from:
https://github.com/microsoft/terminal/issues/538#issuecomment-677017322)
then wezterm will display the text in the same order as the text
renders in Chrome for that github comment.
```
; ./target/debug/wezterm --config experimental_bidi=false ls-fonts --text "عربي فارسی ->"
LeftToRight
0 ع \u{639} x_adv=8 glyph=300 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
2 ر \u{631} x_adv=3.78125 glyph=273 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
4 ب \u{628} x_adv=4 glyph=244 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
6 ي \u{64a} x_adv=4 glyph=363 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
8 \u{20} x_adv=8 glyph=2 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
9 ف \u{641} x_adv=11 glyph=328 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
11 ا \u{627} x_adv=4 glyph=240 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
13 ر \u{631} x_adv=3.78125 glyph=273 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
15 س \u{633} x_adv=10 glyph=278 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
17 ی \u{6cc} x_adv=4 glyph=664 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
19 \u{20} x_adv=8 glyph=2 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
20 - \u{2d} x_adv=8 glyph=276 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
21 > \u{3e} x_adv=8 glyph=338 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
```
```
; ./target/debug/wezterm --config experimental_bidi=true ls-fonts --text "عربي فارسی ->"
RightToLeft
17 ی \u{6cc} x_adv=9 glyph=906 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
15 س \u{633} x_adv=10 glyph=277 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
13 ر \u{631} x_adv=4.78125 glyph=272 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
11 ا \u{627} x_adv=4 glyph=241 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
9 ف \u{641} x_adv=5 glyph=329 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
8 \u{20} x_adv=8 glyph=2 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
6 ي \u{64a} x_adv=9 glyph=904 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
4 ب \u{628} x_adv=4 glyph=243 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
2 ر \u{631} x_adv=5 glyph=273 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
0 ع \u{639} x_adv=6 glyph=301 wezterm.font(".Geeza Pro Interface", {weight="Regular", stretch="Normal", italic=false})
/System/Library/Fonts/GeezaPro.ttc index=2 variation=0, CoreText
LeftToRight
0 \u{20} x_adv=8 glyph=2 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
1 - \u{2d} x_adv=8 glyph=480 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
2 > \u{3e} x_adv=8 glyph=470 wezterm.font("Operator Mono SSm Lig", {weight="DemiLight", stretch="Normal", italic=false})
/Users/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
;
```
refs: https://github.com/wez/wezterm/issues/784
Built using:
```
./FontForge-2020-11-07-21ad4a1-x86_64.AppImage --script $PWD/font-patcher "$PWD/src/unpatched-fonts/NerdFontsSymbolsOnly/NerdFontsSymbolsOnly Template 1000 em.ttf" --powerline --use-single-width-glyphs -out /tmp/nerd-fonts-out --fontawesome --fontawesomeextension --fontlinux --octicons --codicons --powersymbols --powerline --powerlineextra --mdi --weathericons
```
which is everything *except* Pomicons at the time of writing, pending
clarifications of its distribution license
(https://github.com/ryanoasis/nerd-fonts/issues/266)
refs: https://github.com/wez/wezterm/issues/1521
A user reported an issue where having just Roboto Thin installed
caused the title font to use that one, rather than the desired
Roboto Bold.
This commit adjusts the font matching code to accumulate candidates
from each of the font_dirs, locator and built-in font locations,
and then find the best match.
I'm running down a weird thing where the main font renders weirdly
when the title font is 12 pt vs the main font 10 pt.
I thought there might have been a cache invalidation issue and
realized that we could have an A-B-A style issue with the font_ptr
stuff, so I replaced it with an incrementing id.
That didn't fix the thing I was looking at, but does feel a bit
nicer overall.
The default we use on macOS looks decent. Roboto is a similar
looking font that we can use for the other platforms.
I may make it the same on all three once I've had a chance
to compare it on a mac.
This commit adds a CSS box model inspired element / layout
facility, and replaces the hand implemented fancy tab bar
element render.
This makes the code for fancy tab bar much easier to read
and update.
The right status area now expands to the full height of the
tab bar area, and uses a line height of 2.0, which makes
it line up nicely in the tab bar.
Rather than hardcode a fixed default value in the config crate, define
the default as optional and leave it to the font crate to compute
the value.
This is a step towards allow introducing system dependent GUI related
code to resolve/understand the title font: we can't put that directly
in the config crate.
Previously, we'd set it to 100% if any non-zero channel was present,
but this resulted in stronger/darker outlines that were especially
noticeable when the window background was transparent and over a
bright background.
This commit sets the alpha based on the coverage provided to us
by freetype and looks better with and without a transparent window
background.
@dmfay: I think this might be behind what you noticed in your last
comment on #1025.
refs: #1325
`wezterm.font` and `wezterm.font_with_fallback` can now specify
harfbuzz_features and freetype load/render target and flags as
options on a per-font basis.
This allows you to do things such as adjust shaping (eg: ligatures) or
rendering (eg: disable bitmaps, or adjust hinting) for a single font in
a fallback rather than globally for all fonts.
The error message in this issue sounds a lot like the freetype
regression that caused bitmap fonts to fail to render in a recent
freetype release.
Our workaround for that is to used our understanding of whether
a font is a bitmap font or not to avoid calling render.
What we normally see for bitmap TTFs is that setting the scale
fails and we then fall back to using a bitmap.
For Monaco.dfont it appears as though setting the scale succeeds.
This commit introduces some skepticism and prefers to use bitmaps
when available.
This might potentially cause problems in the future if there are
fonts that legitimately have both scaled and bitmap fonts, but
lets see if this helps for now.
refs: https://github.com/wez/wezterm/issues/1419
This is a fairly far-reaching commit. The idea is:
* Introduce a unicode_version config that specifies the default level
of unicode conformance for each newly created Terminal (each Pane)
* The unicode_version is passed down to the `grapheme_column_width`
function which interprets the width based on the version
* `Cell` records the width so that later calculations don't need to
know the unicode version
In a subsequent diff, I will introduce an escape sequence that allows
setting/pushing/popping the unicode version so that it can be overridden
via eg: a shell alias prior to launching an application that uses a
different version of unicode from the default.
This approach allows output from multiple applications with differing
understanding of unicode to coexist on the same screen a little more
sanely.
Note that the default `unicode_version` is set to 9, which means that
emoji presentation selectors are now by-default ignored. This was
selected to better match the level of support in widely deployed
applications.
I expect to raise that default version in the future.
Also worth noting: there are a number of callers of
`unicode_column_width` in things like overlays and lua helper functions
that pass `None` for the unicode version: these will assume the latest
known-to-wezterm/termwiz version of unicode to be desired. If those
overlays do things with emoji presentation selectors, then there may be
some alignment artifacts. That can be tackled in a follow up commit.
refs: #1231
refs: #997
We rely on using freetype in order to support more fonts in more
situations, and we have a deeper existing integration with harfbuzz.
I'm unlikely to come back to allsorts to complete our integration,
and in the meantime, it just adds overhead to build/test and those
builds are taking longer and longer.
I loved the idea of using pure rust for all the font stuff, but
its time is not now.
closes: #587closes: #66
It appears as though Menlo is the only font on macos to contain the
heavy ballot cross symbol, which is commonly used on macos (eg: in
`brew` output).
Our fallback list, despite starting with Menlo, didn't include menlo
itself in the candidates.
Furthermore, `ls-fonts` wouldn never see the result of the system
fallback resolution because it didn't know to try again, and was
using the list of handles from before the fallback.
This commit resolves all of these concerns.
refs: #849
A user reported a problem matching `等距更纱黑体 SC` against
a font that wezterm thought was really named `Sarasa Mono SC`.
This commit attempts to match against other language names,
although the Sarasa font that I found on the MS store doesn't
return `等距更纱黑体` in any of the additional SFNT name tables,
so this isn't a successful change.
The previous commit was partially OK, but the main cause of
emoji being wonky was this bit of macos specific code that I
added ages ago.
Remove that hack and the portion of the code from the previous
commit that was working to undo it.
This should make the baselines consistent across all platforms.
refs: #1203
We now compute the cap-height from the rasterized glyph data.
Moved the scaling action of use_cap_height_to_scale_fallback_fonts from
glyphcache into the font resolver: when enabled, and we have data
about the baseline font and the font being resolved, then the resolving
font will be scaled such that the cap-height of both fonts has the same
pixel size.
The effect of this is that `I` glyphs from both fonts should appear to
have the same height.
Added a row of `I`'s in differing styles at the bottom of styles.txt
to make this easier to visualize.
refs: #1189
This is to handle situations such as some versions of the Terminus
bitmap font, where the individual bitmap strike sizes are broken
out across multiple individual files.
Font matching now passes down the nominal pixel height based on
the current DPI and font scale factor, and will use that to select
the font file that has the closest pixel size.
Previously, it would be potentially undefined which of the Terminus
font files would be selected.
refs: https://github.com/wez/wezterm/issues/1189
This font is a bit funky; the bitmap strikes are only 4px wide:
```
; ftdump gohufont.otb
There is 1 face in this file.
----- Face number: 0 -----
font name entries
family: Gohu GohuFont
style: Regular
postscript: UNAVAILABLE
created: 1904-01-01
modified: 1904-01-01
revision: 1.00
glyph count: 1694
font type entries
FreeType driver: truetype
sfnt wrapped: yes
type: fixed size
direction: horizontal
fixed width: no
glyph names: no
fixed size
0: height 11, width 3
size 11.000, x_ppem 11.000, y_ppem 11.000
1: height 14, width 4
size 14.000, x_ppem 14.000, y_ppem 14.000
charmaps (1)
0: format 4, platform 3, encoding 1 language 0 (active)
```
but using that the cell size isn't right.
We draw from the metrics we compute via cell_metrics to get more
information; we don't get a valid height from that (just 0!), but
we do get the much more plausible width of 8 pixels.
So we take the max of the two techniques for figuring the metrics.
That appears to work out, and also doesn't appear to break emoji
fonts.
refs: #1165
This was a bit of a PITA to run down; the essence of the problem
was that the shaper was returning an x_advance of 0 for U+3000,
which caused wezterm's shaping layer to elide that glyph.
I eventually tracked down the x_advance to be the result of
scaling by an x_scale of 0, which in turn is the result of
harfbuzz not knowing the font size.
The critical portion of this diff is the line that advises
harfbuzz that the font has changed after we've applied the
font size.
The rest is just stuff to make it easier to debug and verify.
This:
```
printf "x\u3000x."
```
Now correctly renders on screen as "x x".
fixes: #1161
- If possible use fontconfig to obtain character coverage instead of
going through all glyphs using freetype.
- `FT_Get_First_Char` typically returns ranges of continuous glyphs itself
and it is far cheaper (I measured a speedup of about 7 times while
catting a large file with lots of funny unicode) to add a range to the
glyph coverage instead of adding each glyph individually.
- Permit adding a range to a RangeSet without performing checks to speed
up things even further.
@H-M-H noticed and suggested this; rather than spawning a thread
for potentially every cluster of graphemes that are being displayed
before we've located a font, constrain things to a single thread
so that we don't burn CPU trying to process the same results
in an excessive number of threads.
Since fonts now use dual source blending, the pixel colors are
interpreted as individual alpha channels. The A component should
be set to 1.0, so that's what we do here.
refs: #1025
The introduction of the Emoji vs Text VS processing means that we might
in some cases not find a glyph with the requested presentation.
In that case, we'd rather show the emoji presentation glyph than none at
all, so we'll retry fallback processing with unspecified presentation.
refs: #997
The recent presentation logic needs to be tweaked to ensure that
we ignore presentation when we reach the fallback font, otherwise
we'll end up in a bad error stack and crash the program.
This commit annotates fonts with a boolean that indicates whether
we think it contains glyphs with emoji presentation, and then
passes the cluster.presentation field down to the shaper.
If the presentation doesn't match the current font in the fallback,
then it will be skipped until we exhaust its options.
`wezterm ls-fonts` also shows whether we think a font has emoji
presentation.
refs: #997
This commit hooks up DECRQM so that we can report that we implement
synchronized updates, and then refines the code that manages sending
data to the terminal model; the first cut at synchronized updates
was a bit simplistic, and now we make a point of "flushing" pending
actions when we start a sync point, and again as soon as we release
the sync point.
This smooths out the jaggies around the orca that I mentioned in
dcbbda7702
and while testing this, I realized that recent parser changes had
mangled processing bundled dec private mode sequences where multiple
modes were specified in the same overall escape sequence. I've
added the missing unit test case for this and made that work again.
refs: https://github.com/wez/wezterm/issues/955
refs: https://github.com/wez/wezterm/issues/882
opentype allows a font to have a weight in the range 0-1000.
MacOS has its own concept of symbolic weight names and opentype
values that is a slightly different scale of boldness to Windows
and Linux.
That means that Medium could be a different range of opentype
weight values depending on the system.
To further complicate things, the font designer can name their
variant with any name they like and assign it an arbitrary
opentype weight value.
For the Operator Mono font, it has Book variant with opentype
weight 325 and a Light variant with an opentype weight of 300.
wezterm was considering these both to have `FontWeight::Light` because
that's how those values were bucketed, which results in amibiguity in
resolve the font and frustration in not being able to access one of the
variants.
This commit changes the `FontWeight` type to now hold the unambiguous
opentype weight value, and to define some symbolic aliases for
some specified weights.
When serializing, if the weight matches a symbolic alias, then that
name will be used in the canonical name (eg: as listed via ls-fonts).
Otherwise, the numeric value will be used.
When parsing the font configuration, wezterm will allow both symbolic
and numeric values.
This allows all of the Operator Mono variants to be referenced
unambiguously, although some variants have to be specified via the
numeric weight:
```
wezterm.font("Operator Mono", {weight=275, stretch="Normal", italic=false}) -- /Users/wez/.fonts/OperatorMono-XLight.otf, FontDirs
wezterm.font("Operator Mono", {weight="Light", stretch="Normal", italic=false}) -- /Users/wez/.fonts/OperatorMono-Light.otf, FontDirs
wezterm.font("Operator Mono", {weight=325, stretch="Normal", italic=false}) -- /Users/wez/.fonts/OperatorMono-Book.otf, FontDirs
wezterm.font("Operator Mono", {weight="DemiLight", stretch="Normal", italic=false}) -- /Users/wez/.fonts/OperatorMono-Medium.otf, FontDirs
wezterm.font("Operator Mono", {weight="Regular", stretch="Normal", italic=false}) -- /Users/wez/.fonts/OperatorMono-Bold.otf, FontDirs
```
https://github.com/wez/wezterm/issues/849#issuecomment-873454483
Change the loader so that it has better matching weight and stretch
characteristics, and ask core text to return all possible candidates
so that we can then apply our CSS-style font matching rules.
Previously, the font descriptor we created would only match the
family name and return the normal/regular variant only.
refs: https://github.com/wez/wezterm/issues/873
This commit adds a slant to *scalable* (not bitmap!) fonts whose
originating font attributes requested italics but for for which
the resolved face is not italic.
refs: #815
This commit introduces the knowledge about whether a font is
scalable or was using bitmap strikes (eg: color emoji bitmaps).
Then that information is used to help figure out whether and
how to scale a glyph.
refs: https://github.com/wez/wezterm/issues/685
I *think* the heart of the issue is that the problematic fonts
don't define a `spacing` property, and we were being stric
about matching it.
This commit changes the behavior to strictly match the spacing
value when it is defined, but to allow an undefined spacing
value to match.
refs: https://github.com/wez/wezterm/issues/726
It now outputs something that you could conceivably put into
your config file, although the intent is to show the canonical
way to reference the individual fonts that were found, rather
than to specify a fully baked list to paste into a config.
eg:
```
; ./target/debug/wezterm ls-fonts
Primary font:
wezterm.font_with_fallback({
-- /home/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontDirs
{family="Operator Mono SSm Lig", weight="DemiLight"},
-- /home/wez/.fonts/OperatorMonoSSmLig-Medium.otf, FontConfig
{family="Operator Mono SSm Lig", weight="DemiLight"},
-- /home/wez/.fonts/MaterialDesignIconsDesktop.ttf, FontDirs
"Material Design Icons Desktop",
-- /home/wez/.fonts/terminus-bold.otb, FontDirs
{family="Terminus", weight="Bold"},
-- /home/wez/.fonts/JetBrainsMono-Regular.ttf, FontDirs
"JetBrains Mono",
-- /home/wez/.fonts/NotoColorEmoji.ttf, FontDirs
"Noto Color Emoji",
-- /home/wez/.fonts/MaterialDesignIconsDesktop.ttf, FontConfig
"Material Design Icons Desktop",
-- /usr/share/fonts/terminus-fonts/ter-u32n.otb, FontConfig
"Terminus",
-- /home/wez/.fonts/JetBrainsMono-Regular.ttf, FontConfig
"JetBrains Mono",
-- /home/wez/.fonts/NotoColorEmoji.ttf, FontConfig
"Noto Color Emoji",
-- <built-in>, BuiltIn
"Last Resort High-Efficiency",
})
```
In earlier times, in an effort to avoid bleeding resources into
child processes, the fontconfig wrapper grew some logic to keep
track of how many fontconfig objects we'd loaded so that we could
aggressively unload it when there were none.
Since that time we've evolved differently pessimistic logic that forces
random fds closed when we spawn children so the critical need for unloading
fontconfig is no longer present.
Importantly, with the over-eager unloading, each font query we make
effectively needs to initialize fontconfig from scratch, which is a
fixed minimum cost of ~5-6ms on my system, and I've seen some traces
with a number as high as 100ms (those systems need `fc-cache` to be
run).
Removing the unloading keeps fontconfig initialized so we only pay
the 5ms cost once, then subsequent queries are in the order of 100us.
It seems difficult/impossible to phrase precisely the constraints
that we want when making a font config query, so this changes our
queries to use relative broad family and postscriptname list operations
and then we parse and filter using our own CSS-inspired font matching
criteria.
refs: #689
