Ultimately, we should find a way to route all emoji access through
the font code, but for now, this patch adds a special case for fonts
that are known to have embedded color bitmaps so we can test them.
This patch does three things:
- Font::has_color_bitmaps() (true if CBLC and CBDT are present)
- Glyph now knows when its bitmap comes from a color bitmap font
- Painter draws color bitmap glyphs with the appropriate scaling etc
This returns the font's size (distance between ascender and descender)
in pixels, rounded up to the nearest integer.
This is the number we want to use in a lot of UI code, so let's have
a friendly API for it instead of ceil'ing the pixel_size() in a million
random places.
This adds the option to pass a subpixel offset when fetching a glyph
from a font, this offset is currently snapped to thirds of a pixel
(i.e. 0, 0.33, 0.66). This is then used when rasterizing the glyph,
which is then cached like usual.
Note that when using subpixel offsets you're trading a bit of space
for accuracy. With the current third of a pixel offsets you can end
up with up to 9 bitmaps per glyph.
