src/base/ftsynth.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftsynth.c                                                              */
   4 /*                                                                         */
   5 /*    FreeType synthesizing code for emboldening and slanting (body).      */
   6 /*                                                                         */
   7 /*  Copyright 2000-2017 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_SYNTHESIS_H
  21 #include FT_INTERNAL_DEBUG_H
  22 #include FT_INTERNAL_OBJECTS_H
  23 #include FT_OUTLINE_H
  24 #include FT_BITMAP_H
  25
  26
  27   /*************************************************************************/
  28   /*                                                                       */
  29   /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  30   /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  31   /* messages during execution.                                            */
  32   /*                                                                       */
  33 #undef  FT_COMPONENT
  34 #define FT_COMPONENT  trace_synth
  35
  36
  37   /*************************************************************************/
  38   /*************************************************************************/
  39   /****                                                                 ****/
  40   /****   EXPERIMENTAL OBLIQUING SUPPORT                                ****/
  41   /****                                                                 ****/
  42   /*************************************************************************/
  43   /*************************************************************************/
  44
  45   /* documentation is in ftsynth.h */
  46
  47   FT_EXPORT_DEF( void )
  48   FT_GlyphSlot_Oblique( FT_GlyphSlot  slot )
  49   {
  50     FT_Matrix    transform;
  51     FT_Outline*  outline;
  52
  53
  54     if ( !slot )
  55       return;
  56
  57     outline = &slot->outline;
  58
  59     /* only oblique outline glyphs */
  60     if ( slot->format != FT_GLYPH_FORMAT_OUTLINE )
  61       return;
  62
  63     /* we don't touch the advance width */
  64
  65     /* For italic, simply apply a shear transform, with an angle */
  66     /* of about 12 degrees.                                      */
  67
  68     transform.xx = 0x10000L;
  69     transform.yx = 0x00000L;
  70
  71     transform.xy = 0x0366AL;
  72     transform.yy = 0x10000L;
  73
  74     FT_Outline_Transform( outline, &transform );
  75   }
  76
  77
  78   /*************************************************************************/
  79   /*************************************************************************/
  80   /****                                                                 ****/
  81   /****   EXPERIMENTAL EMBOLDENING SUPPORT                              ****/
  82   /****                                                                 ****/
  83   /*************************************************************************/
  84   /*************************************************************************/
  85
  86
  87   /* documentation is in ftsynth.h */
  88
  89   FT_EXPORT_DEF( void )
  90   FT_GlyphSlot_Embolden( FT_GlyphSlot  slot )
  91   {
  92     FT_Library  library;
  93     FT_Face     face;
  94     FT_Error    error;
  95     FT_Pos      xstr, ystr;
  96
  97
  98     if ( !slot )
  99       return;
 100
 101     library = slot->library;
 102     face    = slot->face;
 103
 104     if ( slot->format != FT_GLYPH_FORMAT_OUTLINE &&
 105          slot->format != FT_GLYPH_FORMAT_BITMAP  )
 106       return;
 107
 108     /* some reasonable strength */
 109     xstr = FT_MulFix( face->units_per_EM,
 110                       face->size->metrics.y_scale ) / 24;
 111     ystr = xstr;
 112
 113     if ( slot->format == FT_GLYPH_FORMAT_OUTLINE )
 114       FT_Outline_EmboldenXY( &slot->outline, xstr, ystr );
 115
 116     else /* slot->format == FT_GLYPH_FORMAT_BITMAP */
 117     {
 118       /* round to full pixels */
 119       xstr &= ~63;
 120       if ( xstr == 0 )
 121         xstr = 1 << 6;
 122       ystr &= ~63;
 123
 124       /*
 125        * XXX: overflow check for 16-bit system, for compatibility
 126        *      with FT_GlyphSlot_Embolden() since freetype-2.1.10.
 127        *      unfortunately, this function return no informations
 128        *      about the cause of error.
 129        */
 130       if ( ( ystr >> 6 ) > FT_INT_MAX || ( ystr >> 6 ) < FT_INT_MIN )
 131       {
 132         FT_TRACE1(( "FT_GlyphSlot_Embolden:" ));
 133         FT_TRACE1(( "too strong emboldening parameter ystr=%d\n", ystr ));
 134         return;
 135       }
 136       error = FT_GlyphSlot_Own_Bitmap( slot );
 137       if ( error )
 138         return;
 139
 140       error = FT_Bitmap_Embolden( library, &slot->bitmap, xstr, ystr );
 141       if ( error )
 142         return;
 143     }
 144
 145     if ( slot->advance.x )
 146       slot->advance.x += xstr;
 147
 148     if ( slot->advance.y )
 149       slot->advance.y += ystr;
 150
 151     slot->metrics.width        += xstr;
 152     slot->metrics.height       += ystr;
 153     slot->metrics.horiAdvance  += xstr;
 154     slot->metrics.vertAdvance  += ystr;
 155     slot->metrics.horiBearingY += ystr;
 156
 157     /* XXX: 16-bit overflow case must be excluded before here */
 158     if ( slot->format == FT_GLYPH_FORMAT_BITMAP )
 159       slot->bitmap_top += (FT_Int)( ystr >> 6 );
 160   }
 161
 162
 163 /* END */