`FT_Load_Glyph' doesn't generate a bitmap for a non-bitmap glyph
until the user calls `FT_Render_Glyph'. However, it always
allocates memory for bitmaps and copies or decodes the contents of a
bitmap glyph, which can be quite slow for PNG data.
* include/freetype/freetype.h (FT_LOAD_BITMAP_METRICS_ONLY): New
macro.
* src/base/ftobjs.c (FT_Load_Glyph): Unset FT_LOAD_RENDER if
FT_LOAD_BITMAP_METRICS_ONLY is used.
* src/sfnt/ttsbit.c (tt_sbit_decoder_alloc_bitmap,
tt_sbit_decoder_load_bitmap): Add argument to control allocation of
the glyph slot.
(tt_sbit_decoder_load_image, tt_sbit_decoder_load_compound,
tt_face_load_sbit_image): Updated.
* src/pcf/pcfdrivr.c (PCF_Glyph_Load): Quickly exit if
`FT_LOAD_BITMAP_METRICS_ONLY' is set.
* src/pfr/pfrsbit.c, src/pfr/pfrsbit.h (pfr_slot_load_bitmap): Add
argument to control allocation of the glyph slot.
* src/pfr/pfrobjs (pfr_slot_load): Updated.
* src/winfonts/winfnt.c (FNT_Load_Glyph): Ditto.
* docs/CHANGES: Updated.
37e193e935