ttcmap.c

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Hash : f0df85ba
Author :
Date : 2000-06-22T00:17:42

  - MAJOR INTERNAL REDESIGN:

    A lot of internal modifications have been performed lately on the
    source in order to provide the following enhancements:

      - more generic module support:

        The FT_Module type is now defined to represent a handle to a given
        module. The file <freetype/ftmodule.h> contains the FT_Module_Class
        definition, as well as the module-loading public API

        The FT_Driver type is still defined, and still represents a pointer
        to a font driver. Note that FT_Add_Driver is replaced by FT_Add_Module,
        FT_Get_Driver by FT_Get_Module, etc..


      - support for generic glyph image types:

        The FT_Renderer type is a pointer to a module used to perform various
        operations on glyph image.

        Each renderer is capable of handling images in a single format
        (e.g. ft_glyph_format_outline). Its functions are used to:

           - transform an glyph image
           - render a glyph image into a bitmap
           - return the control box (dimensions) of a given glyph image


        The scan converters "ftraster.c" and "ftgrays.c" have been moved
        to the new directory "src/renderer", and are used to provide two
        default renderer modules.

        One corresponds to the "standard" scan-converter, the other to the
        "smooth" one.

        The current renderer can be set through the new function
        FT_Set_Renderer.

        The old raster-related function FT_Set_Raster, FT_Get_Raster and
        FT_Set_Raster_Mode have now disappeared, in favor of the new:

           FT_Get_Renderer
           FT_Set_Renderer

        see the file <freetype/ftrender.h> for more details..

        These changes were necessary to properly support different scalable
        formats in the future, like bi-color glyphs, etc..


      - glyph loader object:

        A new internal object, called a 'glyph loader' has been introduced
        in the base layer. It is used by all scalable format font drivers
        to load glyphs and composites.

        This object has been created to reduce the code size of each driver,
        as each one of them basically re-implemented its functionality.

        See <freetype/internal/ftobjs.h> and the FT_GlyphLoader type for
        more information..



      - FT_GlyphSlot had new fields:

        In order to support extended features (see below), the FT_GlyphSlot
        structure has a few new fields:

           linearHoriAdvance:  this field gives the linearly scaled (i.e.
                               scaled but unhinted) advance width for the glyph,
                               expressed as a 16.16 fixed pixel value. This
                               is useful to perform WYSIWYG text.

           linearVertAdvance:  this field gives the linearly scaled advance
                               height for the glyph (relevant in vertical glyph
                               layouts only). This is useful to perform
                               WYSIWYG text.

        Note that the two above field replace the removed "metrics2" field
        in the glyph slot.

           advance:   this field is a vector that gives the transformed
                      advance for the glyph. By default, it corresponds
                      to the advance width, unless FT_LOAD_VERTICAL_LAYOUT
                      was specified when calling FT_Load_Glyph or FT_Load_Char

           bitmap_left: this field gives the distance in integer pixels from
                        the current pen position to the left-most pixel of
                        a glyph image WHEN IT IS A BITMAP. It is only valid
                        when the "format" field is set to
                        "ft_glyph_format_bitmap", for example, after calling
                        the new function FT_Render_Glyph.

           bitmap_top:  this field gives the distance in integer pixels from
                        the current pen position (located on the baseline) to
                        the top-most pixel of the glyph image WHEN IT IS A
                        BITMAP. Positive values correspond to upwards Y.

           loader:  this is a new private field for the glyph slot. Client
                    applications should not touch it..


      - support for transforms and direct rendering in FT_Load_Glyph:

        Most of the functionality found in <freetype/ftglyph.h> has been
        moved to the core library. Hence, the following:

          - a transform can be specified for a face through FT_Set_Transform.
            this transform is applied by FT_Load_Glyph to scalable glyph images
            (i.e. NOT TO BITMAPS) before the function returns, unless the
            bit flag FT_LOAD_IGNORE_TRANSFORM was set in the load flags..


          - once a glyph image has been loaded, it can be directly converted to
            a bitmap by using the new FT_Render_Glyph function. Note that this
            function takes the glyph image from the glyph slot, and converts
            it to a bitmap whose properties are returned in "face.glyph.bitmap",
            "face.glyph.bitmap_left" and "face.glyph.bitmap_top". The original
            native image might be lost after the conversion.


          - when using the new bit flag FT_LOAD_RENDER, the FT_Load_Glyph
            and FT_Load_Char functions will call FT_Render_Glyph automatically
            when needed.

Download

src/sfnt/ttcmap.c

/***************************************************************************/
/*                                                                         */
/*  ttcmap.c                                                               */
/*                                                                         */
/*    TrueType character mapping table (cmap) support (body).              */
/*                                                                         */
/*  Copyright 1996-2000 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/internal/ftdebug.h>
#include <freetype/internal/tterrors.h>

#include <ttload.h>
#include <ttcmap.h>


  /*************************************************************************/
  /*                                                                       */
  /* 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  trace_ttcmap


  static FT_UInt  code_to_index0( TT_CMapTable*  charmap,
                                  FT_ULong       char_code );
  static FT_UInt  code_to_index2( TT_CMapTable*  charmap,
                                  FT_ULong       char_code );
  static FT_UInt  code_to_index4( TT_CMapTable*  charmap,
                                  FT_ULong       char_code );
  static FT_UInt  code_to_index6( TT_CMapTable*  charmap,
                                  FT_ULong       char_code );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_CharMap_Load                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Loads a given TrueType character map into memory.                  */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face   :: A handle to the parent face object.                      */
  /*    stream :: A handle to the current stream object.                   */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    table  :: A pointer to a cmap object.                              */
  /*                                                                       */
  /* <Return>                                                              */
  /*    TrueType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The function assumes that the stream is already in use (i.e.,      */
  /*    opened).  In case of error, all partially allocated tables are     */
  /*    released.                                                          */
  /*                                                                       */
  LOCAL_FUNC
  FT_Error  TT_CharMap_Load( TT_Face        face,
                             TT_CMapTable*  cmap,
                             FT_Stream      stream )
  {
    FT_Error   error;
    FT_Memory  memory;
    FT_UShort  num_SH, num_Seg, i;

    FT_UShort  u, l;

    TT_CMap0*  cmap0;
    TT_CMap2*  cmap2;
    TT_CMap4*  cmap4;
    TT_CMap6*  cmap6;

    TT_CMap2SubHeader* cmap2sub;
    TT_CMap4Segment*   segments;


    if ( cmap->loaded )
      return TT_Err_Ok;

    memory = stream->memory;

    if ( FILE_Seek( cmap->offset ) )
      return error;

    switch ( cmap->format )
    {
    case 0:
      cmap0 = &cmap->c.cmap0;

      if ( ALLOC( cmap0->glyphIdArray, 256L )            ||
           FILE_Read( (void*)cmap0->glyphIdArray, 256L ) )
         goto Fail;

      cmap->get_index = code_to_index0;
      break;

    case 2:
      num_SH = 0;
      cmap2  = &cmap->c.cmap2;

      /* allocate subheader keys */

      if ( ALLOC_ARRAY( cmap2->subHeaderKeys, 256, FT_UShort ) ||
           ACCESS_Frame( 512L )                                )
        goto Fail;

      for ( i = 0; i < 256; i++ )
      {
        u = GET_UShort() / 8;
        cmap2->subHeaderKeys[i] = u;

        if ( num_SH < u )
          num_SH = u;
      }

      FORGET_Frame();

      /* load subheaders */

      cmap2->numGlyphId = l =
        ( ( cmap->length - 2L * ( 256 + 3 ) - num_SH * 8L ) & 0xFFFF ) / 2;

      if ( ALLOC_ARRAY( cmap2->subHeaders,
                        num_SH + 1,
                        TT_CMap2SubHeader )    ||
           ACCESS_Frame( ( num_SH + 1 ) * 8L ) )
        goto Fail;

      cmap2sub = cmap2->subHeaders;

      for ( i = 0; i <= num_SH; i++ )
      {
        cmap2sub->firstCode     = GET_UShort();
        cmap2sub->entryCount    = GET_UShort();
        cmap2sub->idDelta       = GET_Short();
        /* we apply the location offset immediately */
        cmap2sub->idRangeOffset = GET_UShort() - ( num_SH - i ) * 8 - 2;

        cmap2sub++;
      }

      FORGET_Frame();

      /* load glyph IDs */

      if ( ALLOC_ARRAY( cmap2->glyphIdArray, l, FT_UShort ) ||
           ACCESS_Frame( l * 2L )                           )
        goto Fail;

      for ( i = 0; i < l; i++ )
        cmap2->glyphIdArray[i] = GET_UShort();

      FORGET_Frame();

      cmap->get_index = code_to_index2;
      break;

    case 4:
      cmap4 = &cmap->c.cmap4;

      /* load header */

      if ( ACCESS_Frame( 8L ) )
        goto Fail;

      cmap4->segCountX2    = GET_UShort();
      cmap4->searchRange   = GET_UShort();
      cmap4->entrySelector = GET_UShort();
      cmap4->rangeShift    = GET_UShort();

      num_Seg = cmap4->segCountX2 / 2;

      FORGET_Frame();

      /* load segments */

      if ( ALLOC_ARRAY( cmap4->segments,
                        num_Seg,
                        TT_CMap4Segment )           ||
           ACCESS_Frame( ( num_Seg * 4 + 1 ) * 2L ) )
        goto Fail;

      segments = cmap4->segments;

      for ( i = 0; i < num_Seg; i++ )
        segments[i].endCount      = GET_UShort();

      (void)GET_UShort();

      for ( i = 0; i < num_Seg; i++ )
        segments[i].startCount    = GET_UShort();

      for ( i = 0; i < num_Seg; i++ )
        segments[i].idDelta       = GET_Short();

      for ( i = 0; i < num_Seg; i++ )
        segments[i].idRangeOffset = GET_UShort();

      FORGET_Frame();

      cmap4->numGlyphId = l =
        ( ( cmap->length - ( 16L + 8L * num_Seg ) ) & 0xFFFF ) / 2;

      /* load IDs */

      if ( ALLOC_ARRAY( cmap4->glyphIdArray, l, FT_UShort ) ||
           ACCESS_Frame( l * 2L )                           )
        goto Fail;

      for ( i = 0; i < l; i++ )
        cmap4->glyphIdArray[i] = GET_UShort();

      FORGET_Frame();

      cmap->get_index = code_to_index4;

      cmap4->last_segment = cmap4->segments;
      break;

    case 6:
      cmap6 = &cmap->c.cmap6;

      if ( ACCESS_Frame( 4L ) )
        goto Fail;

      cmap6->firstCode  = GET_UShort();
      cmap6->entryCount = GET_UShort();

      FORGET_Frame();

      l = cmap6->entryCount;

      if ( ALLOC_ARRAY( cmap6->glyphIdArray,
                        cmap6->entryCount,
                        FT_Short )           ||
           ACCESS_Frame( l * 2L )            )
        goto Fail;

      for ( i = 0; i < l; i++ )
        cmap6->glyphIdArray[i] = GET_UShort();

      FORGET_Frame();
      cmap->get_index = code_to_index6;
      break;

    default:   /* corrupt character mapping table */
      return TT_Err_Invalid_CharMap_Format;

    }

    return TT_Err_Ok;

  Fail:
    TT_CharMap_Free( face, cmap );
    return error;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    TT_CharMap_Free                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Destroys a character mapping table.                                */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face :: A handle to the parent face object.                        */
  /*    cmap :: A handle to a cmap object.                                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    TrueType error code.  0 means success.                             */
  /*                                                                       */
  LOCAL_FUNC
  FT_Error  TT_CharMap_Free( TT_Face        face,
                             TT_CMapTable*  cmap )
  {
    FT_Memory  memory;


    if ( !cmap )
      return TT_Err_Ok;

    memory = face->root.driver->root.memory;

    switch ( cmap->format )
    {
    case 0:
      FREE( cmap->c.cmap0.glyphIdArray );
      break;

    case 2:
      FREE( cmap->c.cmap2.subHeaderKeys );
      FREE( cmap->c.cmap2.subHeaders );
      FREE( cmap->c.cmap2.glyphIdArray );
      break;

    case 4:
      FREE( cmap->c.cmap4.segments );
      FREE( cmap->c.cmap4.glyphIdArray );
      cmap->c.cmap4.segCountX2 = 0;
      break;

    case 6:
      FREE( cmap->c.cmap6.glyphIdArray );
      cmap->c.cmap6.entryCount = 0;
      break;

    default:
      /* invalid table format, do nothing */
      ;
    }

    cmap->loaded = FALSE;
    return TT_Err_Ok;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    code_to_index0                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts the character code into a glyph index.  Uses format 0.    */
  /*    `charCode' must be in the range 0x00-0xFF (otherwise 0 is          */
  /*    returned).                                                         */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charCode :: The wanted character code.                             */
  /*    cmap0    :: A pointer to a cmap table in format 0.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index into the glyphs array.  0 if the glyph does not exist. */
  /*                                                                       */
  static
  FT_UInt code_to_index0( TT_CMapTable*  cmap,
                          FT_ULong       charCode )
  {
    TT_CMap0*  cmap0 = &cmap->c.cmap0;


    return ( charCode <= 0xFF ? cmap0->glyphIdArray[charCode] : 0 );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    code_to_index2                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts the character code into a glyph index.  Uses format 2.    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charCode :: The wanted character code.                             */
  /*    cmap2    :: A pointer to a cmap table in format 2.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index into the glyphs array.  0 if the glyph does not exist. */
  /*                                                                       */
  static
  FT_UInt  code_to_index2( TT_CMapTable*  cmap,
                           FT_ULong       charCode )
  {
    FT_UInt             result, index1, offset;
    FT_UInt             char_lo;
    FT_ULong            char_hi;
    TT_CMap2SubHeader*  sh2;
    TT_CMap2*           cmap2;


    cmap2   = &cmap->c.cmap2;
    result  = 0;
    char_lo = (FT_UInt)( charCode & 0xFF );
    char_hi = charCode >> 8;

    if ( char_hi == 0 )
    {
      /* an 8-bit character code - we use the subHeader 0 in this case */
      /* to test whether the character code is in the charmap          */
      if ( cmap2->subHeaderKeys[char_lo] == 0 )
        result = cmap2->glyphIdArray[char_lo];
    }
    else
    {
      /* a 16-bit character code */
      index1 = cmap2->subHeaderKeys[char_hi & 0xFF];
      if ( index1 )
      {
        sh2      = cmap2->subHeaders + index1;
        char_lo -= sh2->firstCode;

        if ( char_lo < sh2->entryCount )
        {
          offset = sh2->idRangeOffset / 2 + char_lo;
          if ( offset < cmap2->numGlyphId )
          {
            result = cmap2->glyphIdArray[offset];
            if ( result )
              result = ( result + sh2->idDelta ) & 0xFFFF;
          }
        }
      }
    }

    return result;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    code_to_index4                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts the character code into a glyph index.  Uses format 4.    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charCode :: The wanted character code.                             */
  /*    cmap4    :: A pointer to a cmap table in format 4.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index into the glyphs array.  0 if the glyph does not exist. */
  /*                                                                       */
  static
  FT_UInt  code_to_index4( TT_CMapTable*  cmap,
                           FT_ULong       charCode )
  {
    FT_UInt          result, index1, segCount;
    TT_CMap4*        cmap4;
    TT_CMap4Segment  *seg4, *limit;


    cmap4    = &cmap->c.cmap4;
    result   = 0;
    segCount = cmap4->segCountX2 / 2;
    seg4     = cmap4->segments;
    limit    = seg4 + segCount;

    /* check against the last segment */
    seg4 = cmap4->last_segment;
    
    /* the following is equivalent to performing two tests, as in         */
    /*                                                                    */
    /*  if ( charCode >= seg4->startCount && charCode <= seg4->endCount ) */
    /*                                                                    */
    /* Yes, that's a bit strange, but it's faster, and the idea behind    */
    /* the cache is to significantly speed up charcode to glyph index     */
    /* conversion.                                                        */

    if ( (FT_ULong)(charCode       - seg4->startCount) <
         (FT_ULong)(seg4->endCount - seg4->startCount) )
      goto Found;

    for ( seg4 = cmap4->segments; seg4 < limit; seg4++ )
    {
      /* the ranges are sorted in increasing order.  If we are out of */
      /* the range here, the char code isn't in the charmap, so exit. */

      if ( charCode > seg4->endCount )
        continue;

      if ( charCode >= seg4->startCount )
        goto Found;
    }
    return 0;

 Found:
    cmap4->last_segment = seg4;

    /* if the idRangeOffset is 0, we can compute the glyph index */
    /* directly                                                  */

    if ( seg4->idRangeOffset == 0 )
      result = ( charCode + seg4->idDelta ) & 0xFFFF;
    else
    {
      /* otherwise, we must use the glyphIdArray to do it */
      index1 = seg4->idRangeOffset / 2
               + ( charCode - seg4->startCount )
               + ( seg4 - cmap4->segments )
               - segCount;

      if ( index1 < cmap4->numGlyphId       &&
           cmap4->glyphIdArray[index1] != 0 )
        result = ( cmap4->glyphIdArray[index1] + seg4->idDelta ) & 0xFFFF;
    }

    return result;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    code_to_index6                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts the character code into a glyph index.  Uses format 6.    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charCode :: The wanted character code.                             */
  /*    cmap6    :: A pointer to a cmap table in format 6.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index into the glyphs array.  0 if the glyph does not exist. */
  /*                                                                       */
  static
  FT_UInt  code_to_index6( TT_CMapTable*  cmap,
                           FT_ULong       charCode )
  {
    TT_CMap6*  cmap6;
    FT_UInt    result = 0;


    cmap6     = &cmap->c.cmap6;
    result    = 0;
    charCode -= cmap6->firstCode;

    if ( charCode < cmap6->entryCount )
      result =  cmap6->glyphIdArray[charCode];

    return result;
  }


/* END */

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kc3-lang/freetype/src/sfnt/ttcmap.c

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src/sfnt/ttcmap.c