ttdriver.c

Qt/Embedded是一个多平台的C++图形用户界面应用程序框架

      left  = 0;
      right = face->num_kern_pairs - 1;

      while ( left <= right )
      {
        TT_Int    middle   = left + ((right-left) >> 1);
        TT_ULong  cur_pair;


        pair     = face->kern_pairs + middle;
        cur_pair = PAIR_TAG( pair->left, pair->right );

        if ( cur_pair == search_tag )
          goto Found;

        if ( cur_pair < search_tag )
          left = middle+1;
        else
          right = middle-1;
      }
    }

  Exit:
    return TT_Err_Ok;

  Found:
    kerning->x = pair->value;
    goto Exit;
  }


#undef PAIR_TAG


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****                           S I Z E S                             ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Set_Char_Sizes                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to reset a size's character sizes (horizontal */
  /*    and vertical) expressed in fractional points.                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    char_width  :: The character width expressed in 26.6 fractional    */
  /*                   points.                                             */
  /*    char_height :: The character height expressed in 26.6 fractional   */
  /*                   points.                                             */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    size        :: A handle to the target size object.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  TT_Error  Set_Char_Sizes( TT_Size     size,
                            TT_F26Dot6  char_width,
                            TT_F26Dot6  char_height,
                            TT_UInt     horz_resolution,
                            TT_UInt     vert_resolution )
  {
    FT_Size_Metrics*  metrics = &size->root.metrics;
    TT_Face           face    = (TT_Face)size->root.face;
    TT_Long           dim_x, dim_y;

    /* This bit flag, when set, indicates that the pixel size must be */
    /* truncated to an integer. Nearly all TrueType fonts have this   */
    /* bit set, as hinting won't work really well otherwise.          */
    /*                                                                */
    /* However, for those rare fonts who do not set it, we override   */
    /* the default computations performed by the base layer. I really */
    /* don't know if this is useful, but hey, that's the spec :-)     */
    /*                                                                */
    if ( (face->header.Flags & 8) == 0 )
    {
      /* Compute pixel sizes in 26.6 units */
      dim_x = (char_width * horz_resolution) / 72;
      dim_y = (char_height * vert_resolution) / 72;

      metrics->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
      metrics->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );

      metrics->x_ppem    = (TT_UShort)(dim_x >> 6);
      metrics->y_ppem    = (TT_UShort)(dim_y >> 6);
    }
    
    size->ttmetrics.valid = FALSE;

    return TT_Reset_Size( size );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Set_Pixel_Sizes                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to reset a size's character sizes (horizontal */
  /*    and vertical) expressed in integer pixels.                         */
  /*                                                                       */
  /* <Input>                                                               */
  /*    pixel_width  :: The character width expressed in integer pixels.   */
  /*                                                                       */
  /*    pixel_height :: The character height expressed in integer pixels.  */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    size         :: A handle to the target size object.                */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code. 0 means success                               */
  /*                                                                       */
  static
  TT_Error  Set_Pixel_Sizes( TT_Size  size,
                             TT_UInt  pixel_width,
                             TT_UInt  pixel_height )
  {
    (void) pixel_width;
    (void) pixel_height;

    /* many things were pre-computed by the base layer */

    size->ttmetrics.valid = FALSE;

    return TT_Reset_Size( size );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Load_Glyph                                                         */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to load a glyph within a given glyph slot.    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    slot        :: A handle to the target slot object where the glyph  */
  /*                   will be loaded.                                     */
  /*                                                                       */
  /*    size        :: A handle to the source face size at which the glyph */
  /*                   must be scaled/loaded/etc.                          */
  /*                                                                       */
  /*    glyph_index :: The index of the glyph in the font file.            */
  /*                                                                       */
  /*    load_flags  :: A flag indicating what to load for this glyph.  The */
  /*                   FTLOAD_??? constants can be used to control the     */
  /*                   glyph loading process (e.g., whether the outline    */
  /*                   should be scaled, whether to load bitmaps or not,   */
  /*                   whether to hint the outline, etc).                  */
  /* <Output>                                                              */
  /*    result      :: A set of bit flags indicating the type of data that */
  /*                   was loaded in the glyph slot (outline, bitmap,      */
  /*                   pixmap, etc).                                       */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  TT_Error  Load_Glyph( TT_GlyphSlot  slot,
                        TT_Size       size,
                        TT_UShort     glyph_index,
                        TT_UInt       load_flags )
  {
    TT_Error  error;


    if ( !slot )
      return TT_Err_Invalid_Glyph_Handle;

    /* check that we want a scaled outline or bitmap */
    if ( !size )
      load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING;

    if ( load_flags & FT_LOAD_NO_SCALE )
      size = NULL;

    /* reset the size object if necessary */
    if ( size )
    {
      /* these two object must have the same parent */
      if ( size->root.face != slot->face )
        return TT_Err_Invalid_Face_Handle;

      if ( !size->ttmetrics.valid )
      {
        if ( FT_SET_ERROR( TT_Reset_Size( size ) ) )
          return error;
      }
    }

    /* now load the glyph outline if necessary */
    error = TT_Load_Glyph( size, slot, glyph_index, load_flags );

    /* force drop-out mode to 2 - irrelevant now */
    /* slot->outline.dropout_mode = 2; */

    return error;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****             C H A R A C T E R   M A P P I N G S                 ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Get_Char_Index                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Uses a charmap to return a given character code's glyph index.     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charmap  :: A handle to the source charmap object.                 */
  /*    charcode :: The character code.                                    */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index.  0 means `undefined character code'.                  */
  /*                                                                       */
  static
  FT_UInt  Get_Char_Index( TT_CharMap  charmap,
                           TT_Long     charcode )
  {
    TT_Error       error;
    TT_Face        face;
    TT_CMapTable*  cmap;
    
    cmap = &charmap->cmap;
    face = (TT_Face)charmap->root.face;

    /* Load table if needed */
    if ( !cmap->loaded )
    {
      SFNT_Interface*  sfnt = (SFNT_Interface*)face->sfnt;
      
      error = sfnt->load_charmap( face, cmap, face->root.stream );
      if (error)
        return error;

      cmap->loaded = TRUE;
    }

    if ( cmap->get_index )
      return cmap->get_index( cmap, charcode );
    else
      return 0;
  }


  /* The FT_DriverInterface structure is defined in ftdriver.h. */

  const FT_DriverInterface  tt_driver_interface =
  {
    sizeof ( TT_DriverRec ),
    sizeof ( TT_FaceRec ),
    sizeof ( TT_SizeRec ),
    sizeof ( FT_GlyphSlotRec ),

    "truetype",      /* driver name                           */
    100,             /* driver version == 1.0                 */
    200,             /* driver requires FreeType 2.0 or above */

    (void*)0,

    (FTDriver_initDriver)        TT_Init_Driver,
    (FTDriver_doneDriver)        TT_Done_Driver,
    (FTDriver_getInterface)      0,     /* no extra interface for now */

    (FTDriver_initFace)          Init_Face,
    (FTDriver_doneFace)          TT_Done_Face,
    (FTDriver_getKerning)        Get_Kerning,

    (FTDriver_initSize)          TT_Init_Size,
    (FTDriver_doneSize)          TT_Done_Size,
    (FTDriver_setCharSizes)      Set_Char_Sizes,
    (FTDriver_setPixelSizes)     Set_Pixel_Sizes,

    (FTDriver_initGlyphSlot)     TT_Init_GlyphSlot,
    (FTDriver_doneGlyphSlot)     TT_Done_GlyphSlot,
    (FTDriver_loadGlyph)         Load_Glyph,

    (FTDriver_getCharIndex)      Get_Char_Index,
  };



  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    getDriverInterface                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    This function is used when compiling the TrueType driver as a      */
  /*    shared library (`.DLL' or `.so').  It will be used by the          */
  /*    high-level library of FreeType to retrieve the address of the      */
  /*    driver's generic interface.                                        */
  /*                                                                       */
  /*    It shouldn't be implemented in a static build, as each driver must */
  /*    have the same function as an exported entry point.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    The address of the TrueType's driver generic interface.  The       */
  /*    format-specific interface can then be retrieved through the method */
  /*    interface->get_format_interface.                                   */
  /*                                                                       */
#ifdef FT_CONFIG_OPTION_DYNAMIC_DRIVERS

  EXPORT_FUNC
  FT_DriverInterface*  getDriverInterface( void )
  {
    return &tt_driver_interface;
  }

#endif /* CONFIG_OPTION_DYNAMIC_DRIVERS */


/* END */