If table tag is not 0x3f, we expect a value between 0 and 62. If this is
not the case, exit with errors.
* src/sfnt/sfwoff2/c: Check whether table tag makes sense.
* src/sfnt/woff2tags.c: Return 0 if tag is out of bounds.
`reconstruct_hmtx' requires `info->x_mins' and `info->num_glyphs' to
reconstruct the hmtx table. In case glyf is not transformed, we call
`get_x_mins' which does the necessary work.
(get_x_mins): New function.
(reconstruct_font): Call get_x_mins.
Set correct value of `face->num_faces' for WOFF2 fonts. This is being
handled separately because we only load the tables for the requested
font face in `woff2_open_font' and create a single-face sfnt stream.
The full discussion is at:
https://lists.gnu.org/archive/html/freetype-devel/2019-08/msg00000.html
* src/sfnt/sfobjs.c (sfnt_open_font): Add parameter `woff2_num_faces'.
(sfnt_init_face): Introduce var `woff2_num_faces', and change
`face->root.num_faces' if `woff2_num_faces' is set.
* src/sfnt/sfwoff2.c (woff2_open_font): Validate requested face index
and handle negative face indices.
* src/sfnt/sfwoff2.h (woff2_open_font): Add parameter `num_faces' to
declaration.
We do this by using `totalSfntSize' as an initial reference, and extending
the buffer when required. This reduces rendering time considerably.
* include/freetype/internal/wofftypes.h (WOFF2_HeaderRec): Add
`totalSfntSize', rename `total_sfnt_size' to `actual_sfnt_size'.
* src/sfnt/sfwoff2.c (write_buf): Add parameter `dst_size' to keep track
of and update total size of stream.
(WRITE_SFNT_BUF, WRITE_SFNT_BUF_AT): Modify macros accordingly.
(pad4, store_loca, reconstruct_glyf, reconstruct_hmtx): Update parameters
to accept `sfnt_size'.
(woff2_open_font): Add variable `sfnt_size'. Use WOFF2 header field
`totalSfntSize' as initial reference (if value makes sense) and allocate
`totalSfntSize' bytes for the sfnt stream. `write_buf' handles
reallocation if and when required. Also resize the stream to
`actual_sfnt_size' after reconstruction.
Add necessary functions to reconstruct loca and hmtx tables (the 2
remaining tables that can have a transform). `woff2_open_font' is now
capable of loading a woff2 font face. This code may still need more
refining and better memory management.
* include/freetype/internal/wofftypes.h (WOFF2_HeaderRec): Add total (final)
size of sfnt stream.
(WOFF2_InfoRec): Add header checksum value.
* src/sfnt/sfobjs.c (sfnt_open_font): Change `face_instance_index' parameter
to its pointer so its value can be modified by `woff2_open_font'.
* src/sfnt/sfwoff2.c: (WRITE_SFNT_BUF_AT): New macro to write into sfnt
buffer at given position.
(write_buf): Add parameter `extend_buf' which allows caller to specify
whether buffer should be reallocated before copying data. Modify macro
`WRITE_SFNT_BUF' accordingly.
(pad4): New function to pad buffer to closest multiple of 4.
(store_loca): Store loca values (provided by `reconstruct_glyf') to output
stream.
(reconstruct_glyf): Calculate loca values and store them.
(reconstruct_hmtx): Reconstruct transformed hmtx table.
(reconstruct_font): Call `reconstruct_hmtx', write table record entries, and
calculate table checksums. Also calculate font checksum and update
`checksumAdjustment' entry in head table.
(woff2_open_font): Open stream for sfnt buffer, swap out input stream and
return.
* src/sfnt/sfwoff2.h (woff2_open_font): Modify parameter to accept pointer
to `face_index'.
Reconstruct `glyf' table if it is transformed in the uncompressed table
stream. Also add necessary structures, macros and functions.
* include/freetype/internal/wofftypes.h (WOFF2_InfoRec,
WOFF2_SubstreamRec, WOFF2_PointRec): New structures.
* src/sfnt/sfwoff2.c (READ_255USHORT, READ_BASE128): Use `FT_SET_ERROR'
to set implicit `error' variable.
(WRITE_SHORT): New macro.
(N_CONTOUR_STREAM, N_POINTS_STREAM, FLAG_STREAM, GLYPH_STREAM,
COMPOSITE_STREAM, BBOX_STREAM, INSTRUCTION_STREAM): New macros to refer
to substreams of the transformed `glyf' tables.
(Read255UShort, ReadBase128): Return errors set by `FT_READ_XXX' macros.
(with_sign, safe_int_addition): New functions to add sign to values
based on a flag and perform safe addition respectively.
(triplet_decode): Decode variable-length (flag, xCoordinate, yCoordinate)
triplet for a simple glyph. See
https://www.w3.org/TR/WOFF2/#triplet_decoding
(store_points): Store decoded points in the glyph buffer.
(compute_bbox): Derive bounding box for a glyph by computing the minimum
and maximum x and y coordinates in the outline.
(reconstruct_glyf): Main routine to reconstruct transformed `glyf' table.
(reconstruct_font): Call `reconstruct_glyf'.
* src/sfnt/sfwoff2.h: Add required constants.
* src/sfnt/woff2tags.h: Move out constants to `sfwoff2.h'.
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.
(woff2_uncompress): 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: Define default max size to prevent overflow.
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 params and iterate over tables.
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'.
Start reconstruction of font.
* src/sfnt/sfwoff2.c (reconstruct_font): New function.
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'.
* 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: Add `sfwoff2.c'.
* src/sfnt/sfnt.c: Include `sfwoff2.c'.
* src/sfnt/sfobjs.c: Check for `wOF2' tag and call `woff2_open_font'.
* src/sfnt/sfwoff2.c, src/sfnt/sfwoff2.h: New files.
Nikhil Ramakrishnan