Previously, `load_from_memory()` just took a raw pointer to the data,
and then manually calculated offsets from that pointer. Instead, let's
use the MappedFile we already have, to stream in the data, to make
things a bit safer. We also now check that the entire file's data was
read, since if there was data left over, then either the file is bad or
we've done something wrong.
I've moved the code directly into `try_load_from_mapped_file()` since
`load_from_memory()` was only called from there. The extra indirection
wasn't adding anything.
Since it will become a stream in a little bit, it should behave like all
non-trivial stream classes, who are not primarily intended to have
shared ownership to make closing behavior more predictable. Across all
uses of MappedFile, there is only one use case of shared mapped files in
LibVideo, which now uses the thin SharedMappedFile wrapper.
Some clients (e.g LibWeb) want to look up typefaces by name. Since we
already store typefaces in a HashMap keyed by family name, let's also
have a nice & fast API that takes advantage of this.
It wasn't enough to do it only for simple glyphs, we need to do it for
composite glyphs as well.
Fixes an issue where some glyph data was misaligned in the output and
thus ended up rendered incorrectly or not at all.
This fixes an issue with some typefaces where the space character has an
advance width, but no glyf entry (and thus no ascent/descent). Before
this change, we'd render whitespace with zero advance in such cases.
This resolves a problem where the kerning value multiplied by the scale
is stored in the cache, even though the code retrieving the value from
the cache does not anticipate it to be scaled. As a result, it leads to
a buggy double multiplication by the scale.
Before this change we always returned the font's point size as the
x-height which was basically never correct.
We now get it from the OS/2 table (if one with version >= 2 is available
in the file). Otherwise we fall back to using the ascent of the 'x'
glyph. Most fonts appear to have a sufficiently modern OS/2 table.
Remove SplitLineSegment and replace it with a FloatLine, nobody was
interested in its extra fields anymore. Also, remove the sorting of
the split segments, this really should not have been done here
anyway, and is not required by the rasterizer anymore. Keeping the
segments in stroke order will also make it possible to generate
stroked path geometry (in future).
Implied point = point created by two subsequent "off curve" points.
Fixes following issues in function that builds glyph path from points:
- If first point is "off curve" it was wrongly treated as "on curve"
which caused wrong first point position in the path.
- If both first and last points in the path are "off curve" implied
point was not created between them which caused wrong path shape in
the end of the path.
This seems mostly harmless and matches what CSS expects from us at the
moment. Eventually our CSS font selection will become more sophisticated
and stop relying on Gfx::FontDatabase for things like this, but for now
it's a simple stopgap that lets websites do "font-family: arial" :^)
The Font class now remembers the results of kerning lookups in a
HashMap. This fixes an issue where text-heavy UI (like WidgetGallery)
would lag when using a UI font with kerning data.
Negative accumulation on the right-hand side of the accumulation bitmap
would wrap around to the left, causing a negative start for certain
lines which resulted in horizontal streaks of lower alpha values.
Prevent this by not writing out of bounds :^)
Fixes#18394
When creating a copy of the font containing only the glyphs that are in
use, we previously looped over all possible code points, instead of the
range of code points that are actually in use (and allocated) in the
font. This is a problem, since we index into the array of widths to find
out if a given glyph is used. This array is only as long as the number
of glyphs the font was created with, causing an out of bounds read when
that number is less than our maximum.
Some fonts (like the Bootstrap Icons webfont) have bogus glyph offsets
in the `loca` table that point past the end of the `glyf` table.
AFAICT other rasterizers simply ignore these glyphs and treat them as if
they were missing. So let's do the same.
This makes https://changelog.serenityos.org/ actually work! :^)
