Matthias Clasen authored Jul 28, 2018 and Behdad Esfahbod committed Jul 18, 2019

Support subpixel positioning with a 4x4 subpixel grid.

When compositing glyphs in the image compositor,
we store the subpixel phases in the high bits of the
glyph index. The _cairo_scaled_glyph_index() macro
has been updated to discard these bits. By storing
the phases in the glyph index, the glyph cache just
keeps working. When loading a glyph, the Freetype
font backend shifts the outline according to the
phases.