chromium/third_party/freetype/src/src/autofit/afshaper.c

/****************************************************************************
 *
 * afshaper.c
 *
 *   HarfBuzz interface for accessing OpenType features (body).
 *
 * Copyright (C) 2013-2024 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * 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.
 *
 */


#include <freetype/freetype.h>
#include <freetype/ftadvanc.h>
#include "afglobal.h"
#include "aftypes.h"
#include "afshaper.h"

#ifdef FT_CONFIG_OPTION_USE_HARFBUZZ


  /**************************************************************************
   *
   * The macro FT_COMPONENT is used in trace mode.  It is an implicit
   * parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
   * messages during execution.
   */
#undef  FT_COMPONENT
#define FT_COMPONENT …


  /*
   * We use `sets' (in the HarfBuzz sense, which comes quite near to the
   * usual mathematical meaning) to manage both lookups and glyph indices.
   *
   * 1. For each coverage, collect lookup IDs in a set.  Note that an
   *    auto-hinter `coverage' is represented by one `feature', and a
   *    feature consists of an arbitrary number of (font specific) `lookup's
   *    that actually do the mapping job.  Please check the OpenType
   *    specification for more details on features and lookups.
   *
   * 2. Create glyph ID sets from the corresponding lookup sets.
   *
   * 3. The glyph set corresponding to AF_COVERAGE_DEFAULT is computed
   *    with all lookups specific to the OpenType script activated.  It
   *    relies on the order of AF_DEFINE_STYLE_CLASS entries so that
   *    special coverages (like `oldstyle figures') don't get overwritten.
   *
   */


  /* load coverage tags */
#undef  COVERAGE
#define COVERAGE( name, NAME, description,             \
                  tag1, tag2, tag3, tag4 ) …


#include "afcover.h"


  /* define mapping between coverage tags and AF_Coverage */
#undef  COVERAGE
#define COVERAGE( name, NAME, description, \
                  tag1, tag2, tag3, tag4 ) …


  static const hb_tag_t*  coverages[] = …;


  /* load HarfBuzz script tags */
#undef  SCRIPT
#define SCRIPT( s, S, d, h, H, ss ) …


  static const hb_script_t  scripts[] = …;


  FT_Error
  af_shaper_get_coverage( AF_FaceGlobals  globals,
                          AF_StyleClass   style_class,
                          FT_UShort*      gstyles,
                          FT_Bool         default_script )
  { … }


  /* construct HarfBuzz features */
#undef  COVERAGE
#define COVERAGE( name, NAME, description,                \
                  tag1, tag2, tag3, tag4 ) …


#include "afcover.h"


  /* define mapping between HarfBuzz features and AF_Coverage */
#undef  COVERAGE
#define COVERAGE( name, NAME, description, \
                  tag1, tag2, tag3, tag4 ) …


  static const hb_feature_t*  features[] = …;


  void*
  af_shaper_buf_create( FT_Face  face )
  { … }


  void
  af_shaper_buf_destroy( FT_Face  face,
                         void*    buf )
  { … }


  const char*
  af_shaper_get_cluster( const char*      p,
                         AF_StyleMetrics  metrics,
                         void*            buf_,
                         unsigned int*    count )
  { … }


  FT_ULong
  af_shaper_get_elem( AF_StyleMetrics  metrics,
                      void*            buf_,
                      unsigned int     idx,
                      FT_Long*         advance,
                      FT_Long*         y_offset )
  { … }


#else /* !FT_CONFIG_OPTION_USE_HARFBUZZ */


  FT_Error
  af_shaper_get_coverage( AF_FaceGlobals  globals,
                          AF_StyleClass   style_class,
                          FT_UShort*      gstyles,
                          FT_Bool         default_script )
  {
    FT_UNUSED( globals );
    FT_UNUSED( style_class );
    FT_UNUSED( gstyles );
    FT_UNUSED( default_script );

    return FT_Err_Ok;
  }


  void*
  af_shaper_buf_create( FT_Face  face )
  {
    FT_UNUSED( face );

    return NULL;
  }


  void
  af_shaper_buf_destroy( FT_Face  face,
                         void*    buf )
  {
    FT_UNUSED( face );
    FT_UNUSED( buf );
  }


  const char*
  af_shaper_get_cluster( const char*      p,
                         AF_StyleMetrics  metrics,
                         void*            buf_,
                         unsigned int*    count )
  {
    FT_Face    face      = metrics->globals->face;
    FT_ULong   ch, dummy = 0;
    FT_ULong*  buf       = (FT_ULong*)buf_;


    while ( *p == ' ' )
      p++;

    GET_UTF8_CHAR( ch, p );

    /* since we don't have an engine to handle clusters, */
    /* we scan the characters but return zero            */
    while ( !( *p == ' ' || *p == '\0' ) )
      GET_UTF8_CHAR( dummy, p );

    if ( dummy )
    {
      *buf   = 0;
      *count = 0;
    }
    else
    {
      *buf   = FT_Get_Char_Index( face, ch );
      *count = 1;
    }

    return p;
  }


  FT_ULong
  af_shaper_get_elem( AF_StyleMetrics  metrics,
                      void*            buf_,
                      unsigned int     idx,
                      FT_Long*         advance,
                      FT_Long*         y_offset )
  {
    FT_Face   face        = metrics->globals->face;
    FT_ULong  glyph_index = *(FT_ULong*)buf_;

    FT_UNUSED( idx );


    if ( advance )
      FT_Get_Advance( face,
                      glyph_index,
                      FT_LOAD_NO_SCALE         |
                      FT_LOAD_NO_HINTING       |
                      FT_LOAD_IGNORE_TRANSFORM,
                      advance );

    if ( y_offset )
      *y_offset = 0;

    return glyph_index;
  }


#endif /* !FT_CONFIG_OPTION_USE_HARFBUZZ */


/* END */