libskrift is a text drawing library for C that is based on libschrift.
The name:
Schrift in libschrift is German for “font” (can also mean “scripture”),
skrift in libskrift is Swedish for “scripture” (cannot mean “font”).
Currently implemented:
Anti-aliased rendering.
Subpixel rendering (RGB, BGR, both horizontal and vertical).
DPI support. (Points, inches, and millimeters can be
exactly converted to pixels.)
(Both horizonal and vertical resolution can be specified.)
Drawing coloured text with 3 primaries, alpha and opacity,
(100% opacity but 0% alpha will cut out the text so it is
transparent, rather than at least as opaque as the background,
where the text is.)
Drawing on RGB, XRGB, ARGB, and RGBA with 8-bit, 16-bit,
32-bit, and 64-bit subpixels, RGB, ARGB, and RGBA with
`float`, `double`, and `long double`, with either
premultipled or non-premultipied alpha.
(The "RGB" in all these formats can be any primitive, but
the screen's is assumed for subpixel rendering, pre- and
postprocessors can be used to change colour space if
required.)
Drawing on surfaces encoded with different endians: host
endian, big endian, or little endian, either on pixel level
or subpixel level.
sRGB gamma function.
Affine transformations on glyphs and texts.
Inter-character spacing.
Not implemented yet
Glyph caching.
Normalise text when glyphs are missing.
Fallback fonts.
Font metrics.
Autokerning.
Vertical text.
Text shaping.
Font searching.
Things that require new features in libschrift
Aliased rendering.
Hinting.
(Better subpixel rendering requires subpixel-aware hinting.)
Affine transformations on parts of outline.
Kerning using font information.
Proper grapheme cluster support.
Draw outline (only) with custom stroke width and shape.
Out of scope:
Bidirectional text.
Text justification.
Line breaks.
Multicolouring.
Underline, overline, strike-thought, ...
Superscript and subscript.
Mathematical formulae formatting.
