lib/freetype/src/truetype/ttdriver.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ttdriver.c                                                             */
   4 /*                                                                         */
   5 /*    TrueType font driver implementation (body).                          */
   6 /*                                                                         */
   7 /*  Copyright 1996-2001, 2002 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_INTERNAL_DEBUG_H
  21 #include FT_INTERNAL_STREAM_H
  22 #include FT_INTERNAL_SFNT_H
  23 #include FT_TRUETYPE_IDS_H
  24
  25 #include "ttdriver.h"
  26 #include "ttgload.h"
  27
  28 #include "tterrors.h"
  29
  30
  31   /*************************************************************************/
  32   /*                                                                       */
  33   /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  34   /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  35   /* messages during execution.                                            */
  36   /*                                                                       */
  37 #undef  FT_COMPONENT
  38 #define FT_COMPONENT  trace_ttdriver
  39
  40
  41   /*************************************************************************/
  42   /*************************************************************************/
  43   /*************************************************************************/
  44   /****                                                                 ****/
  45   /****                                                                 ****/
  46   /****                          F A C E S                              ****/
  47   /****                                                                 ****/
  48   /****                                                                 ****/
  49   /*************************************************************************/
  50   /*************************************************************************/
  51   /*************************************************************************/
  52
  53
  54 #undef  PAIR_TAG
  55 #define PAIR_TAG( left, right )  ( ( (FT_ULong)left << 16 ) | \
  56                                      (FT_ULong)right        )
  57
  58
  59   /*************************************************************************/
  60   /*                                                                       */
  61   /* <Function>                                                            */
  62   /*    Get_Kerning                                                        */
  63   /*                                                                       */
  64   /* <Description>                                                         */
  65   /*    A driver method used to return the kerning vector between two      */
  66   /*    glyphs of the same face.                                           */
  67   /*                                                                       */
  68   /* <Input>                                                               */
  69   /*    face        :: A handle to the source face object.                 */
  70   /*                                                                       */
  71   /*    left_glyph  :: The index of the left glyph in the kern pair.       */
  72   /*                                                                       */
  73   /*    right_glyph :: The index of the right glyph in the kern pair.      */
  74   /*                                                                       */
  75   /* <Output>                                                              */
  76   /*    kerning     :: The kerning vector.  This is in font units for      */
  77   /*                   scalable formats, and in pixels for fixed-sizes     */
  78   /*                   formats.                                            */
  79   /*                                                                       */
  80   /* <Return>                                                              */
  81   /*    FreeType error code.  0 means success.                             */
  82   /*                                                                       */
  83   /* <Note>                                                                */
  84   /*    Only horizontal layouts (left-to-right & right-to-left) are        */
  85   /*    supported by this function.  Other layouts, or more sophisticated  */
  86   /*    kernings, are out of scope of this method (the basic driver        */
  87   /*    interface is meant to be simple).                                  */
  88   /*                                                                       */
  89   /*    They can be implemented by format-specific interfaces.             */
  90   /*                                                                       */
  91   static FT_Error
  92   Get_Kerning( TT_Face     face,
  93                FT_UInt     left_glyph,
  94                FT_UInt     right_glyph,
  95                FT_Vector*  kerning )
  96   {
  97     TT_Kern0_Pair  pair;
  98
  99
 100     if ( !face )
 101       return TT_Err_Invalid_Face_Handle;
 102
 103     kerning->x = 0;
 104     kerning->y = 0;
 105
 106     if ( face->kern_pairs )
 107     {
 108       /* there are some kerning pairs in this font file! */
 109       FT_ULong  search_tag = PAIR_TAG( left_glyph, right_glyph );
 110       FT_Long   left, right;
 111
 112
 113       left  = 0;
 114       right = face->num_kern_pairs - 1;
 115
 116       while ( left <= right )
 117       {
 118         FT_Int    middle = left + ( ( right - left ) >> 1 );
 119         FT_ULong  cur_pair;
 120
 121
 122         pair     = face->kern_pairs + middle;
 123         cur_pair = PAIR_TAG( pair->left, pair->right );
 124
 125         if ( cur_pair == search_tag )
 126           goto Found;
 127
 128         if ( cur_pair < search_tag )
 129           left = middle + 1;
 130         else
 131           right = middle - 1;
 132       }
 133     }
 134
 135   Exit:
 136     return TT_Err_Ok;
 137
 138   Found:
 139     kerning->x = pair->value;
 140     goto Exit;
 141   }
 142
 143
 144 #undef PAIR_TAG
 145
 146
 147   /*************************************************************************/
 148   /*************************************************************************/
 149   /*************************************************************************/
 150   /****                                                                 ****/
 151   /****                                                                 ****/
 152   /****                           S I Z E S                             ****/
 153   /****                                                                 ****/
 154   /****                                                                 ****/
 155   /*************************************************************************/
 156   /*************************************************************************/
 157   /*************************************************************************/
 158
 159
 160   /*************************************************************************/
 161   /*                                                                       */
 162   /* <Function>                                                            */
 163   /*    Set_Char_Sizes                                                     */
 164   /*                                                                       */
 165   /* <Description>                                                         */
 166   /*    A driver method used to reset a size's character sizes (horizontal */
 167   /*    and vertical) expressed in fractional points.                      */
 168   /*                                                                       */
 169   /* <Input>                                                               */
 170   /*    char_width      :: The character width expressed in 26.6           */
 171   /*                       fractional points.                              */
 172   /*                                                                       */
 173   /*    char_height     :: The character height expressed in 26.6          */
 174   /*                       fractional points.                              */
 175   /*                                                                       */
 176   /*    horz_resolution :: The horizontal resolution of the output device. */
 177   /*                                                                       */
 178   /*    vert_resolution :: The vertical resolution of the output device.   */
 179   /*                                                                       */
 180   /* <InOut>                                                               */
 181   /*    size            :: A handle to the target size object.             */
 182   /*                                                                       */
 183   /* <Return>                                                              */
 184   /*    FreeType error code.  0 means success.                             */
 185   /*                                                                       */
 186   static FT_Error
 187   Set_Char_Sizes( TT_Size     size,
 188                   FT_F26Dot6  char_width,
 189                   FT_F26Dot6  char_height,
 190                   FT_UInt     horz_resolution,
 191                   FT_UInt     vert_resolution )
 192   {
 193     FT_Size_Metrics*  metrics  = &size->root.metrics;
 194     FT_Size_Metrics*  metrics2 = &size->metrics;
 195     TT_Face           face     = (TT_Face)size->root.face;
 196     FT_Long           dim_x, dim_y;
 197
 198
 199     *metrics2 = *metrics;
 200
 201     /* This bit flag, when set, indicates that the pixel size must be */
 202     /* truncated to an integer.  Nearly all TrueType fonts have this  */
 203     /* bit set, as hinting won't work really well otherwise.          */
 204     /*                                                                */
 205     if ( ( face->header.Flags & 8 ) != 0 )
 206     {
 207      /* we need to use rounding in the following computations. Otherwise,
 208       * the resulting hinted outlines will be very slightly distorted
 209       */
 210       dim_x = ( ( char_width  * horz_resolution + (36+32*72) ) / 72 ) & -64;
 211       dim_y = ( ( char_height * vert_resolution + (36+32*72) ) / 72 ) & -64;
 212     }
 213     else
 214     {
 215       dim_x = ( ( char_width  * horz_resolution + 36 ) / 72 );
 216       dim_y = ( ( char_height * vert_resolution + 36 ) / 72 );
 217     }
 218
 219     /* we only modify "metrics2", not "metrics", so these changes have */
 220     /* no effect on the result of the auto-hinter when it is used      */
 221     /*                                                                 */
 222     metrics2->x_ppem  = (FT_UShort)( dim_x >> 6 );
 223     metrics2->y_ppem  = (FT_UShort)( dim_y >> 6 );
 224     metrics2->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
 225     metrics2->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );
 226
 227     size->ttmetrics.valid = FALSE;
 228 #ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
 229     size->strike_index    = 0xFFFF;
 230 #endif
 231
 232     return tt_size_reset( size );
 233   }
 234
 235
 236   /*************************************************************************/
 237   /*                                                                       */
 238   /* <Function>                                                            */
 239   /*    Set_Pixel_Sizes                                                    */
 240   /*                                                                       */
 241   /* <Description>                                                         */
 242   /*    A driver method used to reset a size's character sizes (horizontal */
 243   /*    and vertical) expressed in integer pixels.                         */
 244   /*                                                                       */
 245   /* <Input>                                                               */
 246   /*    pixel_width  :: The character width expressed in integer pixels.   */
 247   /*                                                                       */
 248   /*    pixel_height :: The character height expressed in integer pixels.  */
 249   /*                                                                       */
 250   /* <InOut>                                                               */
 251   /*    size         :: A handle to the target size object.                */
 252   /*                                                                       */
 253   /* <Return>                                                              */
 254   /*    FreeType error code.  0 means success.                             */
 255   /*                                                                       */
 256   static FT_Error
 257   Set_Pixel_Sizes( TT_Size  size,
 258                    FT_UInt  pixel_width,
 259                    FT_UInt  pixel_height )
 260   {
 261     FT_UNUSED( pixel_width );
 262     FT_UNUSED( pixel_height );
 263
 264     /* many things have been pre-computed by the base layer */
 265
 266     size->metrics         = size->root.metrics;
 267     size->ttmetrics.valid = FALSE;
 268 #ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
 269     size->strike_index    = 0xFFFF;
 270 #endif
 271
 272     return tt_size_reset( size );
 273   }
 274
 275
 276   /*************************************************************************/
 277   /*                                                                       */
 278   /* <Function>                                                            */
 279   /*    Load_Glyph                                                         */
 280   /*                                                                       */
 281   /* <Description>                                                         */
 282   /*    A driver method used to load a glyph within a given glyph slot.    */
 283   /*                                                                       */
 284   /* <Input>                                                               */
 285   /*    slot        :: A handle to the target slot object where the glyph  */
 286   /*                   will be loaded.                                     */
 287   /*                                                                       */
 288   /*    size        :: A handle to the source face size at which the glyph */
 289   /*                   must be scaled, loaded, etc.                        */
 290   /*                                                                       */
 291   /*    glyph_index :: The index of the glyph in the font file.            */
 292   /*                                                                       */
 293   /*    load_flags  :: A flag indicating what to load for this glyph.  The */
 294   /*                   FTLOAD_??? constants can be used to control the     */
 295   /*                   glyph loading process (e.g., whether the outline    */
 296   /*                   should be scaled, whether to load bitmaps or not,   */
 297   /*                   whether to hint the outline, etc).                  */
 298   /*                                                                       */
 299   /* <Return>                                                              */
 300   /*    FreeType error code.  0 means success.                             */
 301   /*                                                                       */
 302   static FT_Error
 303   Load_Glyph( TT_GlyphSlot  slot,
 304               TT_Size       size,
 305               FT_UShort     glyph_index,
 306               FT_Int32      load_flags )
 307   {
 308     FT_Error  error;
 309
 310
 311     if ( !slot )
 312       return TT_Err_Invalid_Slot_Handle;
 313
 314     /* check whether we want a scaled outline or bitmap */
 315     if ( !size )
 316       load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING;
 317
 318     if ( load_flags & FT_LOAD_NO_SCALE )
 319       size = NULL;
 320
 321     /* reset the size object if necessary */
 322     if ( size )
 323     {
 324       /* these two object must have the same parent */
 325       if ( size->root.face != slot->face )
 326         return TT_Err_Invalid_Face_Handle;
 327
 328       if ( !size->ttmetrics.valid )
 329       {
 330         if ( FT_SET_ERROR( tt_size_reset( size ) ) )
 331           return error;
 332       }
 333     }
 334
 335     /* now load the glyph outline if necessary */
 336     error = TT_Load_Glyph( size, slot, glyph_index, load_flags );
 337
 338     /* force drop-out mode to 2 - irrelevant now */
 339     /* slot->outline.dropout_mode = 2; */
 340
 341     return error;
 342   }
 343
 344
 345   /*************************************************************************/
 346   /*************************************************************************/
 347   /*************************************************************************/
 348   /****                                                                 ****/
 349   /****                                                                 ****/
 350   /****                D R I V E R  I N T E R F A C E                   ****/
 351   /****                                                                 ****/
 352   /****                                                                 ****/
 353   /*************************************************************************/
 354   /*************************************************************************/
 355   /*************************************************************************/
 356
 357
 358   static FT_Module_Interface
 359   tt_get_interface( TT_Driver    driver,
 360                     const char*  tt_interface )
 361   {
 362     FT_Module     sfntd = FT_Get_Module( driver->root.root.library,
 363                                          "sfnt" );
 364     SFNT_Service  sfnt;
 365
 366
 367     /* only return the default interface from the SFNT module */
 368     if ( sfntd )
 369     {
 370       sfnt = (SFNT_Service)( sfntd->clazz->module_interface );
 371       if ( sfnt )
 372         return sfnt->get_interface( FT_MODULE( driver ), tt_interface );
 373     }
 374
 375     return 0;
 376   }
 377
 378
 379   /* The FT_DriverInterface structure is defined in ftdriver.h. */
 380
 381   FT_CALLBACK_TABLE_DEF
 382   const FT_Driver_ClassRec  tt_driver_class =
 383   {
 384     {
 385       ft_module_font_driver     |
 386       ft_module_driver_scalable |
 387 #ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER
 388       ft_module_driver_has_hinter,
 389 #else
 390       0,
 391 #endif
 392
 393       sizeof ( TT_DriverRec ),
 394
 395       "truetype",      /* driver name                           */
 396       0x10000L,        /* driver version == 1.0                 */
 397       0x20000L,        /* driver requires FreeType 2.0 or above */
 398
 399       (void*)0,        /* driver specific interface */
 400
 401       (FT_Module_Constructor)tt_driver_init,
 402       (FT_Module_Destructor) tt_driver_done,
 403       (FT_Module_Requester)  tt_get_interface,
 404     },
 405
 406     sizeof ( TT_FaceRec ),
 407     sizeof ( TT_SizeRec ),
 408     sizeof ( FT_GlyphSlotRec ),
 409
 410
 411     (FT_Face_InitFunc)        tt_face_init,
 412     (FT_Face_DoneFunc)        tt_face_done,
 413     (FT_Size_InitFunc)        tt_size_init,
 414     (FT_Size_DoneFunc)        tt_size_done,
 415     (FT_Slot_InitFunc)        0,
 416     (FT_Slot_DoneFunc)        0,
 417
 418     (FT_Size_ResetPointsFunc) Set_Char_Sizes,
 419     (FT_Size_ResetPixelsFunc) Set_Pixel_Sizes,
 420     (FT_Slot_LoadFunc)        Load_Glyph,
 421
 422     (FT_Face_GetKerningFunc)  Get_Kerning,
 423     (FT_Face_AttachFunc)      0,
 424     (FT_Face_GetAdvancesFunc) 0
 425   };
 426
 427
 428 /* END */