libraries/freetype-2.0.5/ttdriver.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ttdriver.c                                                             */
   4 /*                                                                         */
   5 /*    TrueType font driver implementation (body).                          */
   6 /*                                                                         */
   7 /*  Copyright 1996-2001 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_Kern_0_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     TT_Face           face    = (TT_Face)size->root.face;
 195     FT_Long           dim_x, dim_y;
 196
 197
 198     /* This bit flag, when set, indicates that the pixel size must be */
 199     /* truncated to an integer.  Nearly all TrueType fonts have this  */
 200     /* bit set, as hinting won't work really well otherwise.          */
 201     /*                                                                */
 202     /* However, for those rare fonts who do not set it, we override   */
 203     /* the default computations performed by the base layer.  I       */
 204     /* really don't know whether this is useful, but hey, that's the  */
 205     /* spec :-)                                                       */
 206     /*                                                                */
 207     if ( ( face->header.Flags & 8 ) == 0 )
 208     {
 209       /* Compute pixel sizes in 26.6 units */
 210       dim_x = ( char_width  * horz_resolution ) / 72;
 211       dim_y = ( char_height * vert_resolution ) / 72;
 212
 213       metrics->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
 214       metrics->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );
 215
 216       metrics->x_ppem  = (FT_UShort)( dim_x >> 6 );
 217       metrics->y_ppem  = (FT_UShort)( dim_y >> 6 );
 218     }
 219
 220     size->ttmetrics.valid = FALSE;
 221 #ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
 222     size->strike_index    = 0xFFFF;
 223 #endif
 224
 225     return TT_Reset_Size( size );
 226   }
 227
 228
 229   /*************************************************************************/
 230   /*                                                                       */
 231   /* <Function>                                                            */
 232   /*    Set_Pixel_Sizes                                                    */
 233   /*                                                                       */
 234   /* <Description>                                                         */
 235   /*    A driver method used to reset a size's character sizes (horizontal */
 236   /*    and vertical) expressed in integer pixels.                         */
 237   /*                                                                       */
 238   /* <Input>                                                               */
 239   /*    pixel_width  :: The character width expressed in integer pixels.   */
 240   /*                                                                       */
 241   /*    pixel_height :: The character height expressed in integer pixels.  */
 242   /*                                                                       */
 243   /* <InOut>                                                               */
 244   /*    size         :: A handle to the target size object.                */
 245   /*                                                                       */
 246   /* <Return>                                                              */
 247   /*    FreeType error code.  0 means success.                             */
 248   /*                                                                       */
 249   static FT_Error
 250   Set_Pixel_Sizes( TT_Size  size,
 251                    FT_UInt  pixel_width,
 252                    FT_UInt  pixel_height )
 253   {
 254     FT_UNUSED( pixel_width );
 255     FT_UNUSED( pixel_height );
 256
 257     /* many things have been pre-computed by the base layer */
 258
 259     size->ttmetrics.valid = FALSE;
 260 #ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
 261     size->strike_index    = 0xFFFF;
 262 #endif
 263
 264     return TT_Reset_Size( size );
 265   }
 266
 267
 268   /*************************************************************************/
 269   /*                                                                       */
 270   /* <Function>                                                            */
 271   /*    Load_Glyph                                                         */
 272   /*                                                                       */
 273   /* <Description>                                                         */
 274   /*    A driver method used to load a glyph within a given glyph slot.    */
 275   /*                                                                       */
 276   /* <Input>                                                               */
 277   /*    slot        :: A handle to the target slot object where the glyph  */
 278   /*                   will be loaded.                                     */
 279   /*                                                                       */
 280   /*    size        :: A handle to the source face size at which the glyph */
 281   /*                   must be scaled, loaded, etc.                        */
 282   /*                                                                       */
 283   /*    glyph_index :: The index of the glyph in the font file.            */
 284   /*                                                                       */
 285   /*    load_flags  :: A flag indicating what to load for this glyph.  The */
 286   /*                   FTLOAD_??? constants can be used to control the     */
 287   /*                   glyph loading process (e.g., whether the outline    */
 288   /*                   should be scaled, whether to load bitmaps or not,   */
 289   /*                   whether to hint the outline, etc).                  */
 290   /*                                                                       */
 291   /* <Return>                                                              */
 292   /*    FreeType error code.  0 means success.                             */
 293   /*                                                                       */
 294   static FT_Error
 295   Load_Glyph( TT_GlyphSlot  slot,
 296               TT_Size       size,
 297               FT_UShort     glyph_index,
 298               FT_UInt       load_flags )
 299   {
 300     FT_Error  error;
 301
 302
 303     if ( !slot )
 304       return TT_Err_Invalid_Slot_Handle;
 305
 306     /* check whether we want a scaled outline or bitmap */
 307     if ( !size )
 308       load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING;
 309
 310     if ( load_flags & FT_LOAD_NO_SCALE )
 311       size = NULL;
 312
 313     /* reset the size object if necessary */
 314     if ( size )
 315     {
 316       /* these two object must have the same parent */
 317       if ( size->root.face != slot->face )
 318         return TT_Err_Invalid_Face_Handle;
 319
 320       if ( !size->ttmetrics.valid )
 321       {
 322         if ( FT_SET_ERROR( TT_Reset_Size( size ) ) )
 323           return error;
 324       }
 325     }
 326
 327     /* now load the glyph outline if necessary */
 328     error = TT_Load_Glyph( size, slot, glyph_index, load_flags );
 329
 330     /* force drop-out mode to 2 - irrelevant now */
 331     /* slot->outline.dropout_mode = 2; */
 332
 333     return error;
 334   }
 335
 336
 337   /*************************************************************************/
 338   /*************************************************************************/
 339   /*************************************************************************/
 340   /****                                                                 ****/
 341   /****                                                                 ****/
 342   /****             C H A R A C T E R   M A P P I N G S                 ****/
 343   /****                                                                 ****/
 344   /****                                                                 ****/
 345   /*************************************************************************/
 346   /*************************************************************************/
 347   /*************************************************************************/
 348
 349   /*************************************************************************/
 350   /*                                                                       */
 351   /* <Function>                                                            */
 352   /*    Get_Char_Index                                                     */
 353   /*                                                                       */
 354   /* <Description>                                                         */
 355   /*    Uses a charmap to return a given character code's glyph index.     */
 356   /*                                                                       */
 357   /* <Input>                                                               */
 358   /*    charmap  :: A handle to the source charmap object.                 */
 359   /*    charcode :: The character code.                                    */
 360   /*                                                                       */
 361   /* <Return>                                                              */
 362   /*    Glyph index.  0 means `undefined character code'.                  */
 363   /*                                                                       */
 364   static FT_UInt
 365   Get_Char_Index( TT_CharMap  charmap,
 366                   FT_Long     charcode )
 367   {
 368     FT_Error       error;
 369     TT_Face        face;
 370     TT_CMapTable*  cmap;
 371
 372
 373     cmap = &charmap->cmap;
 374     face = (TT_Face)charmap->root.face;
 375
 376     /* Load table if needed */
 377     if ( !cmap->loaded )
 378     {
 379       SFNT_Interface*  sfnt = (SFNT_Interface*)face->sfnt;
 380
 381
 382       error = sfnt->load_charmap( face, cmap, face->root.stream );
 383       if ( error )
 384         return 0;
 385
 386       cmap->loaded = TRUE;
 387     }
 388
 389     if ( cmap->get_index )
 390       return cmap->get_index( cmap, charcode );
 391     else
 392       return 0;
 393   }
 394
 395
 396   /*************************************************************************/
 397   /*************************************************************************/
 398   /*************************************************************************/
 399   /****                                                                 ****/
 400   /****                                                                 ****/
 401   /****                D R I V E R  I N T E R F A C E                   ****/
 402   /****                                                                 ****/
 403   /****                                                                 ****/
 404   /*************************************************************************/
 405   /*************************************************************************/
 406   /*************************************************************************/
 407
 408
 409   static FT_Module_Interface
 410   tt_get_interface( TT_Driver    driver,
 411                     const char*  interface )
 412   {
 413     FT_Module        sfntd = FT_Get_Module( driver->root.root.library,
 414                                             "sfnt" );
 415     SFNT_Interface*  sfnt;
 416
 417
 418     /* only return the default interface from the SFNT module */
 419     if ( sfntd )
 420     {
 421       sfnt = (SFNT_Interface*)( sfntd->clazz->module_interface );
 422       if ( sfnt )
 423         return sfnt->get_interface( FT_MODULE( driver ), interface );
 424     }
 425
 426     return 0;
 427   }
 428
 429
 430   /* The FT_DriverInterface structure is defined in ftdriver.h. */
 431
 432   FT_CALLBACK_TABLE_DEF
 433   const FT_Driver_Class  tt_driver_class =
 434   {
 435     {
 436       ft_module_font_driver     |
 437       ft_module_driver_scalable |
 438 #ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER
 439       ft_module_driver_has_hinter,
 440 #else
 441       0,
 442 #endif
 443
 444       sizeof ( TT_DriverRec ),
 445
 446       "truetype",      /* driver name                           */
 447       0x10000L,        /* driver version == 1.0                 */
 448       0x20000L,        /* driver requires FreeType 2.0 or above */
 449
 450       (void*)0,        /* driver specific interface */
 451
 452       (FT_Module_Constructor)TT_Init_Driver,
 453       (FT_Module_Destructor) TT_Done_Driver,
 454       (FT_Module_Requester)  tt_get_interface,
 455     },
 456
 457     sizeof ( TT_FaceRec ),
 458     sizeof ( TT_SizeRec ),
 459     sizeof ( FT_GlyphSlotRec ),
 460
 461
 462     (FTDriver_initFace)     TT_Init_Face,
 463     (FTDriver_doneFace)     TT_Done_Face,
 464     (FTDriver_initSize)     TT_Init_Size,
 465     (FTDriver_doneSize)     TT_Done_Size,
 466     (FTDriver_initGlyphSlot)0,
 467     (FTDriver_doneGlyphSlot)0,
 468
 469     (FTDriver_setCharSizes) Set_Char_Sizes,
 470     (FTDriver_setPixelSizes)Set_Pixel_Sizes,
 471     (FTDriver_loadGlyph)    Load_Glyph,
 472     (FTDriver_getCharIndex) Get_Char_Index,
 473
 474     (FTDriver_getKerning)   Get_Kerning,
 475     (FTDriver_attachFile)   0,
 476     (FTDriver_getAdvances)  0
 477   };
 478
 479
 480 #ifdef FT_CONFIG_OPTION_DYNAMIC_DRIVERS
 481
 482
 483   /*************************************************************************/
 484   /*                                                                       */
 485   /* <Function>                                                            */
 486   /*    getDriverClass                                                     */
 487   /*                                                                       */
 488   /* <Description>                                                         */
 489   /*    This function is used when compiling the TrueType driver as a      */
 490   /*    shared library (`.DLL' or `.so').  It will be used by the          */
 491   /*    high-level library of FreeType to retrieve the address of the      */
 492   /*    driver's generic interface.                                        */
 493   /*                                                                       */
 494   /*    It shouldn't be implemented in a static build, as each driver must */
 495   /*    have the same function as an exported entry point.                 */
 496   /*                                                                       */
 497   /* <Return>                                                              */
 498   /*    The address of the TrueType's driver generic interface.  The       */
 499   /*    format-specific interface can then be retrieved through the method */
 500   /*    interface->get_format_interface.                                   */
 501   /*                                                                       */
 502   FT_EXPORT_DEF( const FT_Driver_Class* )
 503   getDriverClass( void )
 504   {
 505     return &tt_driver_class;
 506   }
 507
 508
 509 #endif /* CONFIG_OPTION_DYNAMIC_DRIVERS */
 510
 511
 512 /* END */