freetype1/lib/extend/ftxwidth.c

   1 /*******************************************************************
   2  *
   3  *  ftxwidth.c                                                  1.0
   4  *
   5  *    Glyph Widths (and Heights) fast retrieval extension
   6  *
   7  *  Copyright 1996-1999 by
   8  *  David Turner, Robert Wilhelm, and Werner Lemberg.
   9  *
  10  *  This file is part of the FreeType project, and may only be used
  11  *  modified and distributed under the terms of the FreeType project
  12  *  license, LICENSE.TXT.  By continuing to use, modify, or distribute
  13  *  this file you indicate that you have read the license and
  14  *  understand and accept it fully.
  15  *
  16  *
  17  *  This extension is used to parse the "glyf" table of a TrueType
  18  *  file in order to extract the bbox of a given range of glyphs.
  19  *
  20  *  The bbox is then used to build font unit widths and height
  21  *  that are returned in two parallel arrays.
  22  *
  23  *  This extension is needed by the FreeType/2 OS/2 Font Driver.
  24  *
  25  ******************************************************************/
  26
  27
  28 #include "ftxwidth.h"
  29 #include "ttdebug.h"
  30 #include "ttobjs.h"
  31 #include "ttfile.h"
  32 #include "tttags.h"
  33 #include "ttload.h"
  34
  35 /* Required by the tracing mode */
  36
  37 #undef  TT_COMPONENT
  38 #define TT_COMPONENT  trace_any
  39
  40
  41   /******************************************************************/
  42   /*                                                                */
  43   /*  Function:  TT_Get_Face_Widths                                 */
  44   /*                                                                */
  45   /*  Description: Returns the widths and/or heights of a given     */
  46   /*               range of glyphs for a face.                      */
  47   /*                                                                */
  48   /*  Input:                                                        */
  49   /*     face        ::  face handle                                */
  50   /*                                                                */
  51   /*     first_glyph ::  first glyph in range                       */
  52   /*                                                                */
  53   /*     last_glyph  ::  last glyph in range                        */
  54   /*                                                                */
  55   /*     widths      ::  address of table receiving the widths      */
  56   /*                     expressed in font units (ushorts). Set     */
  57   /*                     this parameter to NULL if you're not       */
  58   /*                     interested by these values.                */
  59   /*                                                                */
  60   /*     heights     ::  address of table receiving the heights     */
  61   /*                     expressed in font units (ushorts).  Set    */
  62   /*                     this parameter to NULL if you're not       */
  63   /*                     interested by these values.                */
  64   /*                                                                */
  65   /*  Returns:                                                      */
  66   /*       Error code                                               */
  67   /*                                                                */
  68   /*                                                                */
  69   /******************************************************************/
  70
  71   EXPORT_FUNC
  72   TT_Error  TT_Get_Face_Widths( TT_Face     face,
  73                                 TT_UShort   first_glyph,
  74                                 TT_UShort   last_glyph,
  75                                 TT_UShort*  widths,
  76                                 TT_UShort*  heights )
  77   {
  78     DEFINE_ALL_LOCALS;
  79
  80     PFace     faze = HANDLE_Face(face);
  81     UShort    n;
  82     Long      table;
  83
  84     ULong     glyf_offset;      /* offset of glyph table in file */
  85     UShort    zero_width  = 0;  /* width of glyph 0  */
  86     UShort    zero_height = 0;  /* height of glyph 0 */
  87
  88     Bool      zero_loaded = 0;
  89
  90 #ifndef TT_HUGE_PTR
  91     PStorage  locations;
  92 #else
  93     Storage TT_HUGE_PTR * locations;
  94 #endif
  95     TT_BBox   bbox;
  96
  97
  98     if ( !faze )
  99       return TT_Err_Invalid_Face_Handle;
 100
 101     if ( last_glyph >= faze->numGlyphs ||
 102          first_glyph > last_glyph      )
 103       return TT_Err_Invalid_Argument;
 104
 105     /* find "glyf" table */
 106     table = TT_LookUp_Table( faze, TTAG_glyf );
 107     if ( table < 0 )
 108     {
 109       PERROR(( "ERROR: there is no glyph table in this font file!\n" ));
 110       return TT_Err_Glyf_Table_Missing;
 111     }
 112     glyf_offset = faze->dirTables[table].Offset;
 113
 114     /* now access stream */
 115     if ( USE_Stream( faze->stream, stream ) )
 116       return error;
 117
 118     locations = faze->glyphLocations + first_glyph;
 119
 120     /* loop to load each glyph in the range */
 121     for ( n = first_glyph; n <= last_glyph; n++ )
 122     {
 123       if ( n + 1 < faze->numGlyphs &&
 124            locations[0] == locations[1] )
 125       {
 126         /* Note : Glyph 0 is always used to indicate a missing glyph   */
 127         /*        in a range. We must thus return its width and height */
 128         /*        where appropriate when we find an undefined glyph.   */
 129         if ( zero_loaded == 0 )
 130         {
 131           if ( FILE_Seek( glyf_offset + faze->glyphLocations[0] ) ||
 132                ACCESS_Frame( 10L ) )
 133             goto Fail;
 134
 135           (void)GET_Short();   /* skip number of contours */
 136
 137           bbox.xMin = GET_Short();
 138           bbox.yMin = GET_Short();
 139           bbox.xMax = GET_Short();
 140           bbox.yMax = GET_Short();
 141
 142           FORGET_Frame();
 143
 144           zero_width  = (UShort)(bbox.xMax - bbox.xMin);
 145           zero_height = (UShort)(bbox.yMax - bbox.yMin);
 146           zero_loaded = 1;
 147         }
 148
 149         if ( widths )
 150           *widths++  = zero_width;
 151
 152         if ( heights )
 153           *heights++ = zero_height;
 154       }
 155       else
 156       {
 157         /* normal glyph, read header */
 158         if ( FILE_Seek( glyf_offset + locations[0] ) ||
 159              ACCESS_Frame( 10L ) )
 160           goto Fail;
 161
 162         (void)GET_Short();  /* skip number of contours */
 163
 164         bbox.xMin = GET_Short();
 165         bbox.yMin = GET_Short();
 166         bbox.xMax = GET_Short();
 167         bbox.yMax = GET_Short();
 168
 169         FORGET_Frame();
 170
 171         if ( widths )
 172           *widths++  = (UShort)(bbox.xMax - bbox.xMin);
 173
 174         if ( heights )
 175           *heights++ = (UShort)(bbox.yMax - bbox.yMin);
 176       }
 177     }
 178
 179   Fail:
 180     DONE_Stream( stream );
 181     return error;
 182   }
 183
 184
 185 /* END */