src/freetype/base/ftextend.c

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftextend.h                                                             */
   4 /*                                                                         */
   5 /*    FreeType extensions implementation (body).                           */
   6 /*                                                                         */
   7 /*  Copyright 1996-2000 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   /*                                                                       */
  20   /*  This is an updated version of the extension component, now located   */
  21   /*  in the main library's source directory.  It allows the dynamic       */
  22   /*  registration/use of various face object extensions through a simple  */
  23   /*  API.                                                                 */
  24   /*                                                                       */
  25   /*************************************************************************/
  26
  27
  28 #include <freetype/internal/ftextend.h>
  29 #include <freetype/internal/ftdebug.h>
  30
  31
  32   /*************************************************************************/
  33   /*                                                                       */
  34   /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  35   /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  36   /* messages during execution.                                            */
  37   /*                                                                       */
  38 #undef  FT_COMPONENT
  39 #define FT_COMPONENT  trace_extend
  40
  41
  42   typedef struct  FT_Extension_Registry_
  43   {
  44     FT_Int              num_extensions;
  45     FT_Long             cur_offset;
  46     FT_Extension_Class  classes[FT_MAX_EXTENSIONS];
  47
  48   } FT_Extension_Registry;
  49
  50
  51   /*************************************************************************/
  52   /*                                                                       */
  53   /* <Function>                                                            */
  54   /*    FT_Init_Extensions                                                 */
  55   /*                                                                       */
  56   /* <Description>                                                         */
  57   /*    Initializes the extension component.                               */
  58   /*                                                                       */
  59   /* <InOut>                                                               */
  60   /*    driver :: A handle to the driver object.                           */
  61   /*                                                                       */
  62   /* <Return>                                                              */
  63   /*    FreeType error code.  0 means success.                             */
  64   /*                                                                       */
  65   LOCAL_FUNC
  66   FT_Error  FT_Init_Extensions( FT_Driver  driver )
  67   {
  68     FT_Error                error;
  69     FT_Memory               memory;
  70     FT_Extension_Registry*  registry;
  71
  72
  73     memory = driver->root.library->memory;
  74     if ( ALLOC( registry, sizeof ( *registry ) ) )
  75       return error;
  76
  77     registry->num_extensions = 0;
  78     registry->cur_offset     = 0;
  79     driver->extensions       = registry;
  80
  81     FT_TRACE2(( "FT_Init_Extensions: success\n" ));
  82
  83     return FT_Err_Ok;
  84   }
  85
  86
  87   /*************************************************************************/
  88   /*                                                                       */
  89   /* <Function>                                                            */
  90   /*    FT_Done_Extensions                                                 */
  91   /*                                                                       */
  92   /* <Description>                                                         */
  93   /*    Finalizes the extension component.                                 */
  94   /*                                                                       */
  95   /* <InOut>                                                               */
  96   /*    driver :: A handle to the driver object.                           */
  97   /*                                                                       */
  98   /* <Return>                                                              */
  99   /*    FreeType error code.  0 means success.                             */
 100   /*                                                                       */
 101   LOCAL_FUNC
 102   FT_Error  FT_Done_Extensions( FT_Driver  driver )
 103   {
 104     FT_Memory  memory = driver->root.memory;
 105
 106
 107     FREE( driver->extensions );
 108     return FT_Err_Ok;
 109   }
 110
 111
 112   /*************************************************************************/
 113   /*                                                                       */
 114   /* <Function>                                                            */
 115   /*    FT_Register_Extension                                              */
 116   /*                                                                       */
 117   /* <Description>                                                         */
 118   /*    Registers a new extension.                                         */
 119   /*                                                                       */
 120   /* <InOut>                                                               */
 121   /*    driver :: A handle to the driver object.                           */
 122   /*    class  :: A pointer to a class describing the extension.           */
 123   /*                                                                       */
 124   /* <Return>                                                              */
 125   /*    FreeType error code.  0 means success.                             */
 126   /*                                                                       */
 127   FT_EXPORT_FUNC( FT_Error )  FT_Register_Extension(
 128                                 FT_Driver            driver,
 129                                 FT_Extension_Class*  clazz )
 130   {
 131     FT_Extension_Registry*  registry;
 132
 133
 134     if ( !driver )
 135       return FT_Err_Invalid_Driver_Handle;
 136
 137     if ( !clazz )
 138       return FT_Err_Invalid_Argument;
 139
 140     registry = (FT_Extension_Registry*)driver->extensions;
 141     if ( registry )
 142     {
 143       FT_Int               n   = registry->num_extensions;
 144       FT_Extension_Class*  cur = registry->classes + n;
 145
 146
 147       if ( n >= FT_MAX_EXTENSIONS )
 148         return FT_Err_Too_Many_Extensions;
 149
 150       *cur = *clazz;
 151
 152       cur->offset  = registry->cur_offset;
 153
 154       registry->num_extensions++;
 155       registry->cur_offset +=
 156         ( cur->size + FT_ALIGNMENT - 1 ) & -FT_ALIGNMENT;
 157
 158       FT_TRACE1(( "FT_Register_Extension: `%s' successfully registered\n",
 159                   cur->id ));
 160     }
 161
 162     return FT_Err_Ok;
 163   }
 164
 165
 166   /*************************************************************************/
 167   /*                                                                       */
 168   /* <Function>                                                            */
 169   /*    FT_Get_Extension                                                   */
 170   /*                                                                       */
 171   /* <Description>                                                         */
 172   /*    Queries an extension block by an extension ID string.              */
 173   /*                                                                       */
 174   /* <Input>                                                               */
 175   /*    face                :: A handle to the face object.                */
 176   /*    extension_id        :: An ID string identifying the extension.     */
 177   /*                                                                       */
 178   /* <Output>                                                              */
 179   /*    extension_interface :: A generic pointer, usually pointing to a    */
 180   /*                           table of functions implementing the         */
 181   /*                           extension interface.                        */
 182   /*                                                                       */
 183   /* <Return>                                                              */
 184   /*    A generic pointer to the extension block.                          */
 185   /*                                                                       */
 186   FT_EXPORT_FUNC( void* )  FT_Get_Extension(
 187                              FT_Face      face,
 188                              const char*  extension_id,
 189                              void**       extension_interface )
 190   {
 191     FT_Extension_Registry*  registry;
 192
 193
 194     if ( !face || !extension_id || !extension_interface )
 195       return 0;
 196
 197     registry = (FT_Extension_Registry*)face->driver->extensions;
 198     if ( registry && face->extensions )
 199     {
 200       FT_Extension_Class*  cur   = registry->classes;
 201       FT_Extension_Class*  limit = cur + registry->num_extensions;
 202
 203
 204       for ( ; cur < limit; cur++ )
 205         if ( strcmp( cur->id, extension_id ) == 0 )
 206         {
 207           *extension_interface = cur->interface;
 208
 209           FT_TRACE1(( "FT_Get_Extension: got `%s'\n", extension_id ));
 210
 211           return (void*)((char*)face->extensions + cur->offset);
 212         }
 213     }
 214
 215     /* could not find the extension id */
 216
 217     FT_ERROR(( "FT_Get_Extension: couldn't find `%s'\n", extension_id ));
 218
 219     *extension_interface = 0;
 220
 221     return 0;
 222   }
 223
 224
 225   /*************************************************************************/
 226   /*                                                                       */
 227   /* <Function>                                                            */
 228   /*    FT_Destroy_Extensions                                              */
 229   /*                                                                       */
 230   /* <Description>                                                         */
 231   /*    Destroys all extensions within a face object.                      */
 232   /*                                                                       */
 233   /* <InOut>                                                               */
 234   /*    face :: A handle to the face object.                               */
 235   /*                                                                       */
 236   /* <Return>                                                              */
 237   /*    FreeType error code.  0 means success.                             */
 238   /*                                                                       */
 239   /* <Note>                                                                */
 240   /*    Called by the face object destructor.                              */
 241   /*                                                                       */
 242   LOCAL_FUNC
 243   FT_Error  FT_Destroy_Extensions( FT_Face  face )
 244   {
 245     FT_Extension_Registry*  registry;
 246     FT_Memory               memory;
 247
 248
 249     registry = (FT_Extension_Registry*)face->driver->extensions;
 250     if ( registry && face->extensions )
 251     {
 252       FT_Extension_Class*  cur   = registry->classes;
 253       FT_Extension_Class*  limit = cur + registry->num_extensions;
 254
 255
 256       for ( ; cur < limit; cur++ )
 257       {
 258         char*  ext = (char*)face->extensions + cur->offset;
 259
 260         if ( cur->finalize )
 261           cur->finalize( ext, face );
 262       }
 263
 264       memory = face->driver->root.memory;
 265       FREE( face->extensions );
 266     }
 267
 268     return FT_Err_Ok;
 269   }
 270
 271
 272   /*************************************************************************/
 273   /*                                                                       */
 274   /* <Function>                                                            */
 275   /*    FT_Create_Extensions                                               */
 276   /*                                                                       */
 277   /* <Description>                                                         */
 278   /*    Creates an extension object within a face object for all           */
 279   /*    registered extensions.                                             */
 280   /*                                                                       */
 281   /* <InOut>                                                               */
 282   /*    face :: A handle to the face object.                               */
 283   /*                                                                       */
 284   /* <Return>                                                              */
 285   /*    FreeType error code.  0 means success.                             */
 286   /*                                                                       */
 287   /* <Note>                                                                */
 288   /*    Called by the face object constructor.                             */
 289   /*                                                                       */
 290   LOCAL_FUNC
 291   FT_Error  FT_Create_Extensions( FT_Face  face )
 292   {
 293     FT_Extension_Registry*  registry;
 294     FT_Memory               memory;
 295     FT_Error                error;
 296
 297
 298     face->extensions = 0;
 299
 300     /* load extensions registry; exit successfully if none is there */
 301
 302     registry = (FT_Extension_Registry*)face->driver->extensions;
 303     if ( !registry )
 304       return FT_Err_Ok;
 305
 306     memory = face->driver->root.memory;
 307     if ( ALLOC( face->extensions, registry->cur_offset ) )
 308       return error;
 309
 310     {
 311       FT_Extension_Class*  cur   = registry->classes;
 312       FT_Extension_Class*  limit = cur + registry->num_extensions;
 313
 314
 315       for ( ; cur < limit; cur++ )
 316       {
 317         char*  ext = (char*)face->extensions + cur->offset;
 318
 319         if ( cur->init )
 320         {
 321           error = cur->init( ext, face );
 322           if ( error )
 323             break;
 324         }
 325       }
 326     }
 327
 328     return error;
 329   }
 330
 331
 332 /* END */