Fonts are now loaded with FT_LOAD_COLOR and we recognize and support
the FT_PIXEL_MODE_BGRA pixel mode.
This is mapped to a CAIRO_FORMAT_ARGB32 surface, that is blitted
as-is (instead of used as a mask like we do for gray and mono glyphs).
Furthermore, since many emojis are double-width, we add initial
support for double-width glyphs.
These are assumed to always be utf8. When PRINT:ing an utf8 character,
we check its width, and add empty "spacer" cells after the cell with
the multi-column glyph.
When rendering, we render the columns in each row backwards. This
ensures the spacer cells get cleared *before* we render the glyph (so
that we don't end up erasing part of the glyph).
Finally, emoji fonts are usually bitmap fonts with *large*
glyphs. These aren't automatically scaled down. I.e. even if we
request a glyph of 13 pixels, we might end up getting a 100px glyph.
To handle this, fontconfig must be configured to scale bitmap
fonts. When it is, we can look at the 'scalable' and 'pixelsizefixup'
properties, and use these to scale the rendered glyph.
Replace with generic error log messages that simply says the
ESC/CSI/OSC sequence is unhandled. This can mean either invalid or
unimplemented, depending on the context.
A top-level font now has a list of fallback fonts. When a glyph cannot
be found, we try each fallback font in turn, until we either find one
that has the glyph, or until we've exhausted the list.
To make this actually work in practise (read: to make performance
acceptable), the cache is re-worked and is now populated on demand.
It also supports non-ASCII characters, by using the 4-byte unicode
character as index instead.
Since having an array that can be indexed by a 4-byte value isn't
really viable, we now have a simple hash table instead of an array.
This patch takes a bit from the foreground color value in a
cell (todo: split up foreground/background into bitfields with a
separate field for 'foreground/background' has been set), and only
re-renders cells that aren't marked as clean.
Note: we use a 'clean' bit rather than a 'dirty' bit to make it easy
to erase cells - we can (keep doing) do that by simply memsetting a
cell range to 0.
Initial POC that uses freetype to render the glyphs. The bitmap
produced by freetype contains the alpha value.
We use this bitmap in a mask surface and then draw the final glyph
with cairo by applying the source rgb using the OVER operator and the
freetype generated alpha mask as surface mask.
Note that we only support grayscale antialiasing (and no
antialiasing).
We are probably not setting the antialias options correctly either.
