The old method was nice, but had an issue that's intractible without
significant reworking in how we do shaping: combining glyphs need to
position relative to the glyph they're combining with, but if we re-
center that glyph, it will be off by some amount.
Apologies to Apple, the previous comments in this section of the code
were not correct-- `shouldSubpixelQuantizeFonts` does pretty much what
the minimal documentation for it says it does, it simply quantizes the
position of the glyph and nothing more. Various bugs when testing while
writing the old code that led me to include those comments made me not
realize that the positioning is actually a lot simpler than it seems.
With this version of the positioning there are never any cut-off rows or
columns of pixels on the edges of anything and everything scales as it
should... I hope. I checked pretty thoroughly this time and I'm like 99%
sure this is correct in all cases.
This adds functionality for choosing different normalization metrics for
each fallback font. It's not exposed as a config option, but could be in
the future, which would probably go a long way towards addressing
concerns like #7929.
The currently available reference metrics are, in priority order:
`ic_width, ex_height, cap_height, line_height, em_size`. The default
value is `ic_width`.
By priority order, I mean that if the chosen metric is not defined in
the fallback font, we move to the next metric in the list---we don't
normalize by an estimated metric from the fallback font (however, we're
happy to use an estimated metric from the primary font, that's how
`ic_width` normalization between CJK and Latin fonts work). This extends
the pattern that was used between `ic_width` and `ex_height` in the
existing hardcoded rule. `line_height` is always defined, so the buck
stops there.
What motivated me to implement this was the fact that, with the existing
hardcoded rule, the embedded symbols-only Nerd Font was always scaled up
by a factor of 1.2, which turned out to be an important reason why it's
been difficult to make icon scaling work to everyone's satisfaction.
Accordingly, the symbols-only font is the first to take advantage of the
new functionality. If this PR is merged, #7917 is no longer needed. (To
limit the scope of this PR, it only includes the minimal changes to let
icon scaling take advantage of this functionality. I may submit a
follow-up PR with some further icon scaling improvement enabled by
this.)
Move size adjustment logic out of `Entry`, I understand the impulse to
put it there but it results in passing a lot of stuff around which isn't
great.
Rework `add(...)` in to `add(...)` and `addDeferred(...)`, faces are
passed directly now instead of passing an entry, and an options struct
is used instead of positional arguments for things like style, fallback,
and size adjustment.
Change size adjustment test back to a half pixel tolerance instead of 5%
because the previous commit (allowing fractional pixel sizes) fixed the
root cause of large differences.
The old math didn't allow fractional pixels on the left and bottom, and
stretched glyphs vertically since the height was always rounded up. At
very small font sizes this looked good, but at medium and even large
sizes this just made things inconsistent and janky.
These new calculations are practically pixel-identical to whatever
CoreText is doing in 99% of cases, and the remaining cases seem to be
some sort of auto-hinting since it's internal features of the glyph
getting repositioned.
Over all, I still prefer this to CoreText's quantize option, but if this
causes further issues we should probably just revert the whole thing and
go ahead and add an extra pixel of padding to the bottom and left...
Using the "subpixel quantization" option for rendering our glyph was
creating bad edge cases where we'd lose the bottom or left row / column
of pixels in a glyph sometimes. I investigated the exact effect of this
option and it seems like beyond quantizing the position and scale it's
also doing some rudimentary auto-hinting. That said, the auto-hinting
doesn't do that much for us, and the fact that it horizontally snaps
coordinates to thirds of a pixel instead of whole pixels makes things
worse in terms of legibility at small pixel sizes, so ultimately it's
better with our own handling anyway.
I extensively compared the result of Apple's option with our own manual
quantization here and I'm pretty sure this will always match the whole
pixel sizes, and where it differs (other than things like crossbars) it
seems to make glyphs generally more legible not less.
Nerd font icons were ***WAY*** too big depending on your font setup,
this is because we were always using the full cell height when the nerd
font patcher instead uses an "icon height" for most things. The patcher
calculates the icon height as two thirds of the font's cap height and
one third of the line height, but I've chosen to instead use 1.2 times
the cap height for more consistent results across fonts-- if the user
wants their icons bigger, they can use the `adjust-icon-height` metric
modifier (and they can also use it to make them smaller if they want
that for some reason).
I also adjusted the attributes to user horizontal cover + vertical fit
for `^` stretch modes (proportional scaling but scale up), which makes
it so that it never exceeds the cell size, since first it covers
horizontally and then scales down to fit vertically if necessary;
previously, if there were a particularly wide glyph that was scaled with
cover/cover it would exceed the available width and overflow in to
neighboring cells which wasn't good.
Icons were often WAY too big before because they were filling the whole
cell in height, which isn't great lol. This commit adds an `icon_height`
metric which is used to constrain glyphs that shouldn't be the size of
the entire cell.
This was subtly wrong in a way that was most obvious when text switched
from regular to bold, where it would seem to wiggle since the bearings
of each letter would shift by a pixel in either direction. This affected
applications like fzf which uses bold to dynamically highlight the line
you have selected.
Previously produced very wrong values when calling Collection.setSize,
since it was assuming that the provided face had the same point size as
the primary face, which isn't true during resize-- so instead we just
have faces keep track of their set size, this is generally useful.
This better harmonizes fallback fonts with the primary font by matching
the heights of lowercase letters. This should be a big improvement for
users who use mixed scripts and so rely heavily on fallback fonts.
This generally adjusts the bearings of any glyph whose original advance
was narrower than the cell, which helps a lot with proportional fallback
glyphs so they aren't just left-aligned. This only applies to situations
where the glyph was originally narrower than the cell, so that we don't
mess up ligatures, and this centers the old advance width in the new one
rather than adjusting proportionally, because otherwise we can mess up
glyphs that are meant to align with others when placed vertically.
We can reintroduce `advance` if we ever want to do proportional string
drawing, but we don't use it anywhere right now. And we also don't need
`sprite` anymore since that was just there to disable constraints for
sprites back when we did them on the GPU.
This mostly applies to powerline glyphs, but is also relevant for heavy
bracket characters, which need to always be 1 wide otherwise they look
silly because they misalign depending on if there's a space after them
or not.
Previously, many glyphs were having their top and right row/column of
pixels clipped off due to not accounting for the slight bearing in the
width and height calculation here.
This is in preparation to move constraint off the GPU to simplify our
shaders, instead we only need to constrain once at raster time and never
again.
This also significantly reworks the freetype renderGlyph function to be
generally much cleaner and more straightforward.
This commit doesn't actually apply the constraints to anything yet, that
will be in following commits.
This commit changes a LOT of areas of the code to use decl literals
instead of redundantly referring to the type.
These changes were mostly driven by some regex searches and then manual
adjustment on a case-by-case basis.
I almost certainly missed quite a few places where decl literals could
be used, but this is a good first step in converting things, and other
instances can be addressed when they're discovered.
I tested GLFW+Metal and building the framework on macOS and tested a GTK
build on Linux, so I'm 99% sure I didn't introduce any syntax errors or
other problems with this. (fingers crossed)
This commit is quite large because it's fairly interconnected and can't
be split up in a logical way. The main part of this commit is that alpha
blending is now always done in the Display P3 color space, and depending
on the configured `window-colorspace` colors will be converted from sRGB
or assumed to already be Display P3 colors. In addition, a config option
`text-blending` has been added which allows the user to configure linear
blending (AKA "gamma correction"). Linear alpha blending also applies to
images and makes custom shaders receive linear colors rather than sRGB.
In addition, an experimental option has been added which corrects linear
blending's tendency to make dark text look too thin and bright text look
too thick. Essentially it's a correction curve on the alpha channel that
depends on the luminance of the glyph being drawn.
This sets the stage for dynamically adjusting the sizes of fallback
fonts based on the primary font's face metrics. It also removes a lot of
unnecessary work when loading fallback fonts, since we only actually use
the metrics based on the parimary font.
This is achieved by rendering to an alpha-only context rather than a
normal single-channel context, and adjusting the brightness at which
coretext thinks it's drawing the glyph, which affects how it applies
font smoothing (which is what `font-thicken` enables).
macOS bitmap-only fonts are a poorly documented format, which are often
distributed as `.dfont` or `.dfon` files. They use a 'bhed' table in
place of the usual 'head', but the table format is byte-identical, so
enabling the use of bitmap-only fonts only requires us to properly fetch
this table while calculating metrics.
ref: https://fontforge.org/docs/techref/bitmaponlysfnt.html
- Simplifies and clarifies the math for how the bounding box for
rendered glyphs is computed
- Reduces margin from 2px between glyphs to 1px by only padding the
bottom and right side of each glyph
- Avoids excessive padding to glyph box when font thicken is enabled or
when using a synthetic bold (it was previously 4x as much padding as
necessary in some cases)
Variable font init used to just select the first available predefined
instance, if there were any, which is often not desirable- using
createFontDescriptorFromData instead of createFontDescritorsFromData
ensures that the default variation config is selected. In the future we
should probably allow selection of predefined instances, but for now
this is the correct behavior.
I found this bug when adding the metrics calculation test case for
CoreText, hence why fixing it is part of the same commit.
Unify grid metrics calculations by relying on shared logic mostly based
on values directly from the font tables, this deduplicates a lot of code
and gives us more control over how we interpret various metrics.
Also separate metrics for underlined, strikethrough, and overline
thickness and position, and box drawing thickness, so that they can
individually be adjusted as the user desires.
This commit makes CoreText behave a lot like FreeType where we set the
variation axes on the deferred face load. This fixes a bug where the
`slnt` variation axis could not be set with CoreText with the Monaspace
Argon Variable font.
This was a bug found in Discord. Specifically, with the Monaspace Argon
Variable font, the `slnt` variation axis could not be set with CoreText.
I'm not sure _exactly_ what causes this but I suspect it has to do with
the `slnt` axis being a negative value. I'm not sure if this is a bug
with CoreText or not.
What was happening was that with CoreText, we set the variation axes
during discovery and expect them to be preserved in the resulting
discovered faces. That seems to be true with the `wght` axis but not the
`slnt` axis for whatever reason.
Fixes#2364
This adds the bold, italic, and bold italic variants of JB Mono so it is
built-in. This also fixes up the naming convention for the embedded font
files across tests and removes redundant embedded font files.
At certain font sizes, this avoids clipping the text. This is due to a
limitation of the CoreText API, which does not provide a way to measure
the exact size of the text that will be rendered when antialiasing is
enabled.
Qwerasd