kc3-lang/freetype/src/sfnt/ttgpos.h

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• Hash : 8f286c86
  Author :
  Date : 2024-01-19T16:42:48
  

  Add support for kerning from 'GPOS' tables.
  
  This commit adds support for kerning from 'GPOS' tables, while maintaining
  support for basic 'kern' tables.  `FT_HAS_KERNING` will be true for a font
  with either available and `FT_Get_Kerning` will still use the basic 'kern'
  table data if avilable, otherwise check the GPOS 'kern' feature.
  
  This feature is disabled by default; it can be enabled with the
  `TT_CONFIG_OPTION_GPOS_KERNING` flag.
  
  Only basic kerning (pair positioning with just an x advance) is supported
  from the GPOS layout features; support for that was added to make the
  existing `FT_Get_Kerning` API more consistently functional.  FreeType does
  not intend to extend itself to further GPOS functionality though; a
  higher-level library like HarfBuzz can be used instead for that.
  
  * include/freetype/config/ftoption.h, include/devel/ftoption.h
  (TT_CONFIG_OPTION_GPOS_KERNING): New configuration option.
  
  * include/freetype/internal/fttrace.h: Add `ttgpos` trace handler.
  
  * include/freetype/internal/sfnt.h (SFNT_Interface): Add `load_gpos` and
  `get_gpos_kerning` fields.
  (FT_DEFINE_SFNT_INTERFACE): Updated.
  
  * include/freetype/internal/tttypes.h: Include `fttypes.h`.
  (TT_FaceRec) [TT_CONFIG_OPTION_GPOS_KERNING]: Add `gpos_table` and
  `gpos_kerning_available` fields.
  
  * src/sfnt/ttgpos.c, src/sfnt/ttgpos.h: New files.
  
  * src/sfnt/sfdriver.c [TT_CONFIG_OPTION_GPOS_KERNING]: Include `ttgpos.h`.
  (sfnt_interface): Updated.
  
  * src/sfnt/sfnt.c: Include `ttgpos.c`.
  
  * src/sfnt/sfobjs.c [TT_CONFIG_OPTION_GPOS_KERNING]: Include `ttgpos.h`.
  (sfnt_load_face) [TT_CONFIG_OPTION_GPOS_KERNING]: Load and free GPOS kerning
  data; check GPOS kerning availability.
  
  * src/truetype/ttdriver.c (tt_get_kerning): Use GPOS kerning if there's no
  'kern' table.
  

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• src/sfnt/ttgpos.h

• /****************************************************************************
   *
   * ttgpos.c
   *
   *   Load the TrueType GPOS table.  The only GPOS layout feature this
   *   currently supports is kerning, from x advances in the pair adjustment
   *   layout feature.
   *
   * Copyright (C) 2024 by
   * David Saltzman
   *
   * This file is part of the FreeType project, and may only be used,
   * modified, and distributed under the terms of the FreeType project
   * license, LICENSE.TXT.  By continuing to use, modify, or distribute
   * this file you indicate that you have read the license and
   * understand and accept it fully.
   */
  
  
  #ifndef TTGPOS_H_
  #define TTGPOS_H_
  
  
  #include <freetype/internal/ftstream.h>
  #include <freetype/internal/tttypes.h>
  
  
  FT_BEGIN_HEADER
  
  
  #ifdef TT_CONFIG_OPTION_GPOS_KERNING
  
    FT_LOCAL( FT_Error  )
    tt_face_load_gpos( TT_Face    face,
                       FT_Stream  stream );
  
    FT_LOCAL( void )
    tt_face_done_gpos( TT_Face  face );
  
    FT_LOCAL( FT_Int )
    tt_face_get_gpos_kerning( TT_Face  face,
                              FT_UInt  left_glyph,
                              FT_UInt  right_glyph );
  
  #endif /* TT_CONFIG_OPTION_GPOS_KERNING */
  
  
  FT_END_HEADER
  
  #endif /* TTGPOS_H_ */
  
  
  /* END */
  

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