thirdparty/freetype-2.3.12/src/base/ftadvanc.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftadvanc.c                                                             */
   4 /*                                                                         */
   5 /*    Quick computation of advance widths (body).                          */
   6 /*                                                                         */
   7 /*  Copyright 2008, 2009 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
  18
  19 #include <ft2build.h>
  20 #include FT_ADVANCES_H
  21 #include FT_INTERNAL_OBJECTS_H
  22
  23
  24   static FT_Error
  25   _ft_face_scale_advances( FT_Face    face,
  26                            FT_Fixed*  advances,
  27                            FT_UInt    count,
  28                            FT_Int32   flags )
  29   {
  30     FT_Fixed  scale;
  31     FT_UInt   nn;
  32
  33
  34     if ( flags & FT_LOAD_NO_SCALE )
  35       return FT_Err_Ok;
  36
  37     if ( face->size == NULL )
  38       return FT_Err_Invalid_Size_Handle;
  39
  40     if ( flags & FT_LOAD_VERTICAL_LAYOUT )
  41       scale = face->size->metrics.y_scale;
  42     else
  43       scale = face->size->metrics.x_scale;
  44
  45     /* this must be the same scaling as to get linear{Hori,Vert}Advance */
  46     /* (see `FT_Load_Glyph' implementation in src/base/ftobjs.c)        */
  47
  48     for ( nn = 0; nn < count; nn++ )
  49       advances[nn] = FT_MulDiv( advances[nn], scale, 64 );
  50
  51     return FT_Err_Ok;
  52   }
  53
  54
  55    /* at the moment, we can perform fast advance retrieval only in */
  56    /* the following cases:                                         */
  57    /*                                                              */
  58    /*  - unscaled load                                             */
  59    /*  - unhinted load                                             */
  60    /*  - light-hinted load                                         */
  61
  62 #define LOAD_ADVANCE_FAST_CHECK( flags )                            \
  63           ( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING )    || \
  64             FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT )
  65
  66
  67   /* documentation is in ftadvanc.h */
  68
  69   FT_EXPORT_DEF( FT_Error )
  70   FT_Get_Advance( FT_Face    face,
  71                   FT_UInt    gindex,
  72                   FT_Int32   flags,
  73                   FT_Fixed  *padvance )
  74   {
  75     FT_Face_GetAdvancesFunc  func;
  76
  77
  78     if ( !face )
  79       return FT_Err_Invalid_Face_Handle;
  80
  81     if ( gindex >= (FT_UInt)face->num_glyphs )
  82       return FT_Err_Invalid_Glyph_Index;
  83
  84     func = face->driver->clazz->get_advances;
  85     if ( func && LOAD_ADVANCE_FAST_CHECK( flags ) )
  86     {
  87       FT_Error  error;
  88
  89
  90       error = func( face, gindex, 1, flags, padvance );
  91       if ( !error )
  92         return _ft_face_scale_advances( face, padvance, 1, flags );
  93
  94       if ( error != FT_ERROR_BASE( FT_Err_Unimplemented_Feature ) )
  95         return error;
  96     }
  97
  98     return FT_Get_Advances( face, gindex, 1, flags, padvance );
  99   }
 100
 101
 102   /* documentation is in ftadvanc.h */
 103
 104   FT_EXPORT_DEF( FT_Error )
 105   FT_Get_Advances( FT_Face    face,
 106                    FT_UInt    start,
 107                    FT_UInt    count,
 108                    FT_Int32   flags,
 109                    FT_Fixed  *padvances )
 110   {
 111     FT_Face_GetAdvancesFunc  func;
 112     FT_UInt                  num, end, nn;
 113     FT_Error                 error = FT_Err_Ok;
 114
 115
 116     if ( !face )
 117       return FT_Err_Invalid_Face_Handle;
 118
 119     num = (FT_UInt)face->num_glyphs;
 120     end = start + count;
 121     if ( start >= num || end < start || end > num )
 122       return FT_Err_Invalid_Glyph_Index;
 123
 124     if ( count == 0 )
 125       return FT_Err_Ok;
 126
 127     func = face->driver->clazz->get_advances;
 128     if ( func && LOAD_ADVANCE_FAST_CHECK( flags ) )
 129     {
 130       error = func( face, start, count, flags, padvances );
 131       if ( !error )
 132         goto Exit;
 133
 134       if ( error != FT_ERROR_BASE( FT_Err_Unimplemented_Feature ) )
 135         return error;
 136     }
 137
 138     error = FT_Err_Ok;
 139
 140     if ( flags & FT_ADVANCE_FLAG_FAST_ONLY )
 141       return FT_Err_Unimplemented_Feature;
 142
 143     flags |= (FT_UInt32)FT_LOAD_ADVANCE_ONLY;
 144     for ( nn = 0; nn < count; nn++ )
 145     {
 146       error = FT_Load_Glyph( face, start + nn, flags );
 147       if ( error )
 148         break;
 149
 150       padvances[nn] = ( flags & FT_LOAD_VERTICAL_LAYOUT )
 151                       ? face->glyph->advance.y
 152                       : face->glyph->advance.x;
 153     }
 154
 155     if ( error )
 156       return error;
 157
 158   Exit:
 159     return _ft_face_scale_advances( face, padvances, count, flags );
 160   }
 161
 162
 163 /* END */