Copy un-transformed tables to the sfnt stream.
* src/sfnt/sfwoff2.c: (WRITE_SFNT_BUF): New macro.
(write_buf): New function. Extend memory of `dst' buffer and copy
bytes from `src'.
(compute_ULong_sum): New function. Calculate checksum of table.
(reconstruct_font): Change `FT_Byte* sfnt' to `FT_Byte**
sfnt_bytes'. This has been done because we reallocate memory to
`sfnt' multiple times, which may change the pointer value of `sfnt'.
This new pointer must be propogated back to the caller. Same reason
for using a double pointer in `write_buf'.
* src/sfnt/woff2tags.h (WOFF2_DEFAULT_MAX_SIZE): New macro used for
overflow checking.
Uncompressed buffer is now an `FT_Stream'.
Perform basic checks and start iterating over tables.
* src/sfnt/sfwoff2.c (stream_close, find_table, read_num_hmetrics):
New functions.
(reconstruct_font): Modify parameters and iterate over tables.
(woff2_open_font): Updated.
We `handle' TTCs by modifying the `indices' array to point to only
those tables that are part of the requested `face_index'.
Set and use `num_tables' in `WOFF2_TtcFont'.
* src/sfnt/sfwoff2.c (reconstruct_font): New function.
(woff2_open_font): Start reconstruction of font.
Change `KnownTags' to a function (`woff2_known_tags'). This avoids
introducing a global constant array. This function returns the
specified index without *any* checks. The caller must ensure that
`index' is within array limits.
* src/sfnt/sfwoff2.c (woff2_open_font): Change `KnownTags[...]'
notation to `woff2_known_tags( ... )'.
* src/sfnt/woff2tags.c: Perform changes.
* src/sfnt/woff2tags.h: Update definitions.
WOFF2 compressed stream is now uncompressed if Brotli is available.
This data is stored in a separate buffer (uncompressed_buf) because
it does not contain direct table data. Certain tables have
transformations applied to them, and they must be reconstructed
before we can write those tables to the SFNT stream.
`face_index' is now being passed as a parameter to
`woff2_open_font'.
* src/sfnt/sfobjs.c (sfnt_open_font): Add parameter
`face_instance_index'.
* src/sfnt/sfwoff2.c (woff2_uncompress): New function.
(woff2_open_font): Call `woff2_uncompress'.
(compute_first_table_offset): Fix return type.
* src/sfnt/sfwoff2.h (woff2_open_font): Modify declaration.
Check for WOFF2 tag, call `woff2_open_font', and implement it to read
header according to specification.
* include/freetype/internal/fttrace.h: Add `sfwoff2.c'.
* src/sfnt/rules.mk (SFNT_DRV_SRC): Add `sfwoff2.c'.
* src/sfnt/sfnt.c: Include `sfwoff2.c'.
* src/sfnt/sfobjs.c (sfnt_open_font): Check for `wOF2' tag and call
`woff2_open_font'.
* src/sfnt/sfwoff2.c, src/sfnt/sfwoff2.h: New files.
Nikhil Ramakrishnan