Still missing: Support for negative bitmap pitch and subpixel offset
of source bitmap.
* include/freetype/ftbitmap.h, src/base/ftbitmap.c
(FT_Bitmap_Blend): New function.
This monster commit was created by applying Nikhil's scripts
`docconverter.py' and `markify.py' to all C header and source files,
followed up by minor manual clean-up.
No change in functionality, of course.
I used commit f7419907bc6044b9b7057f9789866426c804ba82 from
https://github.com/nikramakrishnan/freetype-docs.git.
Bug introduced after release 2.8.
* src/base/ftbitmap.c (ft_bitmap_assure_buffer): We use
`FT_QALLOC_MULT', which doesn't zero out the buffer. Adjust the
bitmap copying code to take care of this fact.
Also reported as
https://bugs.chromium.org/p/chromium/issues/detail?id=791317
* src/base/ftbitmap.c (ft_bitmap_assure_buffer): If increasing the
bitmap size needs a larger bitmap buffer, assure that the new memory
areas are initialized also.
The documentation of `FT_Bitmap_Convert' says that multiple calls do
proper reallocation of the target FT_Bitmap object. However, this
failed for the sequence
non-empty bitmap
empty bitmap
non-empty bitmap
Reason was that `FT_Bitmap_Convert' only reallocated the bitmap
buffer if it became too small; it didn't make the buffer smaller.
For an empty bitmap following a non-empty one, only the buffer
dimension got set to zero, without deallocation. If the next call
was a non-empty buffer again, an assertion in `ft_mem_qrealloc' was
triggered.
* src/base/ftbitmap.c (FT_Bitmap_Convert): Always reallocate target
buffer to the correct size.
* docs/CHANGES: Document it.
Prevent division by zero by a transparent color.
* src/base/ftbitmap.c (ft_gray_for_premultiplied_srgb_bgra):
Return 0 immediately, when alpha channel is zero.
A new load flag, FT_LOAD_COLOR, makes FreeType load color
embedded-bitmaps, following this draft specification
https://color-emoji.googlecode.com/git/specification/v1.html
which defines two new SFNT tables, `CBDT' and `CBLC' (named and
modeled after `EBDT' and `EBLC', respectively). The color bitmaps
are stored in the new FT_PIXEL_MODE_BGRA format to represent BGRA
pre-multiplied sRGB images. If PNG support is available, PNG color
images as defined in the same proposed specification are supported
also.
Note that color bitmaps are converted to grayscale if client didn't
ask for color.
* builds/unix/configure.raw: Search for libpng.
Add `--without-png' option.
* devel/ftoption.h, include/freetype/config/ftoption.h
(FT_CONFIG_OPTION_USE_PNG): New macro.
* include/freetype/freetype.h (FT_LOAD_COLOR): New load flag.
* include/freetype/ftimage.h (FT_Pixel_Mode): Add
`FT_PIXEL_MODE_BGRA'.
* include/freetype/tttags.h (TTAG_CBDT, TTAG_CBLC): New tags.
* src/base/ftbitmap.c (FT_Bitmap_Embolden): Updated.
(ft_gray_for_premultiplied_srgb_bgra): New function.
(FT_Bitmap_Convert): Handle FT_PIXEL_MODE_BGRA.
* src/sfnt/pngshim.c, src/sfnt/pngshim.h: New files.
* src/sfnt/sfnt.c: Include `pngshim.c'.
* src/sfnt/ttsbit.c: Include FT_BITMAP_H and `pngshim.h'
(tt_face_load_eblc): Load `CBLC'.
(tt_sbit_decoder_init): Load `CBDT'.
(tt_sbit_decoder_alloc_bitmap): Pass load flags to select between
color and grayscale bitmaps.
Set `num_grays'. This is used by `ftview' to choose the blending
algorithm.
(tt_sbit_decoder_load_byte_aligned,
tt_sbit_decoder_load_bit_aligned, tt_sbit_decoder_load_compound,
tt_sbit_decoder_load_image): Pass load flag.
s/write/pwrite/.
Don't call `tt_sbit_decoder_alloc_bitmap'.
Updated.
(tt_sbit_decoder_load_png) [FT_CONFIG_OPTION_USE_PNG]: New function.
(tt_sbit_decoder_load_bitmap): Pass load flag.
Handle new glyph formats 17, 18, and 19.
Call `tt_sbit_decoder_alloc_bitmap'.
Flatten color bitmaps if necessary.
(tt_face_load_sbit_image): Updated.
* src/sfnt/rules.mk (SFNT_DRV_SRC): Add `pngshim.c'.
* docs/CHANGES: Updated.
This is essentially a mechanical conversion, adding inclusion of
`FT_INTERNAL_DEBUG_H' where necessary, and providing the macros for
stand-alone compiling modes of the rasterizer modules.
To convert the remaining occurrences of FT_Err_XXX and friends it is
necessary to rewrite the code. Note, however, that it doesn't harm
if some cases are not handled since FT_THROW is a no-op.
