include/ftcache.h

   1 /***************************************************************************/
   2 /*                                                                         */
   3 /*  ftcache.h                                                              */
   4 /*                                                                         */
   5 /*    FreeType Cache subsystem (specification).                            */
   6 /*                                                                         */
   7 /*  Copyright 1996-2008, 2010, 2013, 2014 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 #ifndef __FTCACHE_H__
  20 #define __FTCACHE_H__
  21
  22
  23 #include <ft2build.h>
  24 #include FT_GLYPH_H
  25
  26
  27 FT_BEGIN_HEADER
  28
  29
  30   /*************************************************************************
  31    *
  32    * <Section>
  33    *    cache_subsystem
  34    *
  35    * <Title>
  36    *    Cache Sub-System
  37    *
  38    * <Abstract>
  39    *    How to cache face, size, and glyph data with FreeType~2.
  40    *
  41    * <Description>
  42    *   This section describes the FreeType~2 cache sub-system, which is used
  43    *   to limit the number of concurrently opened @FT_Face and @FT_Size
  44    *   objects, as well as caching information like character maps and glyph
  45    *   images while limiting their maximum memory usage.
  46    *
  47    *   Note that all types and functions begin with the `FTC_' prefix.
  48    *
  49    *   The cache is highly portable and thus doesn't know anything about the
  50    *   fonts installed on your system, or how to access them.  This implies
  51    *   the following scheme:
  52    *
  53    *   First, available or installed font faces are uniquely identified by
  54    *   @FTC_FaceID values, provided to the cache by the client.  Note that
  55    *   the cache only stores and compares these values, and doesn't try to
  56    *   interpret them in any way.
  57    *
  58    *   Second, the cache calls, only when needed, a client-provided function
  59    *   to convert an @FTC_FaceID into a new @FT_Face object.  The latter is
  60    *   then completely managed by the cache, including its termination
  61    *   through @FT_Done_Face.  To monitor termination of face objects, the
  62    *   finalizer callback in the `generic' field of the @FT_Face object can
  63    *   be used, which might also be used to store the @FTC_FaceID of the
  64    *   face.
  65    *
  66    *   Clients are free to map face IDs to anything else.  The most simple
  67    *   usage is to associate them to a (pathname,face_index) pair that is
  68    *   used to call @FT_New_Face.  However, more complex schemes are also
  69    *   possible.
  70    *
  71    *   Note that for the cache to work correctly, the face ID values must be
  72    *   *persistent*, which means that the contents they point to should not
  73    *   change at runtime, or that their value should not become invalid.
  74    *
  75    *   If this is unavoidable (e.g., when a font is uninstalled at runtime),
  76    *   you should call @FTC_Manager_RemoveFaceID as soon as possible, to let
  77    *   the cache get rid of any references to the old @FTC_FaceID it may
  78    *   keep internally.  Failure to do so will lead to incorrect behaviour
  79    *   or even crashes.
  80    *
  81    *   To use the cache, start with calling @FTC_Manager_New to create a new
  82    *   @FTC_Manager object, which models a single cache instance.  You can
  83    *   then look up @FT_Face and @FT_Size objects with
  84    *   @FTC_Manager_LookupFace and @FTC_Manager_LookupSize, respectively.
  85    *
  86    *   If you want to use the charmap caching, call @FTC_CMapCache_New, then
  87    *   later use @FTC_CMapCache_Lookup to perform the equivalent of
  88    *   @FT_Get_Char_Index, only much faster.
  89    *
  90    *   If you want to use the @FT_Glyph caching, call @FTC_ImageCache, then
  91    *   later use @FTC_ImageCache_Lookup to retrieve the corresponding
  92    *   @FT_Glyph objects from the cache.
  93    *
  94    *   If you need lots of small bitmaps, it is much more memory efficient
  95    *   to call @FTC_SBitCache_New followed by @FTC_SBitCache_Lookup.  This
  96    *   returns @FTC_SBitRec structures, which are used to store small
  97    *   bitmaps directly.  (A small bitmap is one whose metrics and
  98    *   dimensions all fit into 8-bit integers).
  99    *
 100    *   We hope to also provide a kerning cache in the near future.
 101    *
 102    *
 103    * <Order>
 104    *   FTC_Manager
 105    *   FTC_FaceID
 106    *   FTC_Face_Requester
 107    *
 108    *   FTC_Manager_New
 109    *   FTC_Manager_Reset
 110    *   FTC_Manager_Done
 111    *   FTC_Manager_LookupFace
 112    *   FTC_Manager_LookupSize
 113    *   FTC_Manager_RemoveFaceID
 114    *
 115    *   FTC_Node
 116    *   FTC_Node_Unref
 117    *
 118    *   FTC_ImageCache
 119    *   FTC_ImageCache_New
 120    *   FTC_ImageCache_Lookup
 121    *
 122    *   FTC_SBit
 123    *   FTC_SBitCache
 124    *   FTC_SBitCache_New
 125    *   FTC_SBitCache_Lookup
 126    *
 127    *   FTC_CMapCache
 128    *   FTC_CMapCache_New
 129    *   FTC_CMapCache_Lookup
 130    *
 131    *************************************************************************/
 132
 133
 134   /*************************************************************************/
 135   /*************************************************************************/
 136   /*************************************************************************/
 137   /*****                                                               *****/
 138   /*****                    BASIC TYPE DEFINITIONS                     *****/
 139   /*****                                                               *****/
 140   /*************************************************************************/
 141   /*************************************************************************/
 142   /*************************************************************************/
 143
 144
 145   /*************************************************************************
 146    *
 147    * @type: FTC_FaceID
 148    *
 149    * @description:
 150    *   An opaque pointer type that is used to identity face objects.  The
 151    *   contents of such objects is application-dependent.
 152    *
 153    *   These pointers are typically used to point to a user-defined
 154    *   structure containing a font file path, and face index.
 155    *
 156    * @note:
 157    *   Never use NULL as a valid @FTC_FaceID.
 158    *
 159    *   Face IDs are passed by the client to the cache manager that calls,
 160    *   when needed, the @FTC_Face_Requester to translate them into new
 161    *   @FT_Face objects.
 162    *
 163    *   If the content of a given face ID changes at runtime, or if the value
 164    *   becomes invalid (e.g., when uninstalling a font), you should
 165    *   immediately call @FTC_Manager_RemoveFaceID before any other cache
 166    *   function.
 167    *
 168    *   Failure to do so will result in incorrect behaviour or even
 169    *   memory leaks and crashes.
 170    */
 171   typedef FT_Pointer  FTC_FaceID;
 172
 173
 174   /************************************************************************
 175    *
 176    * @functype:
 177    *   FTC_Face_Requester
 178    *
 179    * @description:
 180    *   A callback function provided by client applications.  It is used by
 181    *   the cache manager to translate a given @FTC_FaceID into a new valid
 182    *   @FT_Face object, on demand.
 183    *
 184    * <Input>
 185    *   face_id ::
 186    *     The face ID to resolve.
 187    *
 188    *   library ::
 189    *     A handle to a FreeType library object.
 190    *
 191    *   req_data ::
 192    *     Application-provided request data (see note below).
 193    *
 194    * <Output>
 195    *   aface ::
 196    *     A new @FT_Face handle.
 197    *
 198    * <Return>
 199    *   FreeType error code.  0~means success.
 200    *
 201    * <Note>
 202    *   The third parameter `req_data' is the same as the one passed by the
 203    *   client when @FTC_Manager_New is called.
 204    *
 205    *   The face requester should not perform funny things on the returned
 206    *   face object, like creating a new @FT_Size for it, or setting a
 207    *   transformation through @FT_Set_Transform!
 208    */
 209   typedef FT_Error
 210   (*FTC_Face_Requester)( FTC_FaceID  face_id,
 211                          FT_Library  library,
 212                          FT_Pointer  req_data,
 213                          FT_Face*    aface );
 214
 215   /* */
 216
 217
 218   /*************************************************************************/
 219   /*************************************************************************/
 220   /*************************************************************************/
 221   /*****                                                               *****/
 222   /*****                      CACHE MANAGER OBJECT                     *****/
 223   /*****                                                               *****/
 224   /*************************************************************************/
 225   /*************************************************************************/
 226   /*************************************************************************/
 227
 228
 229   /*************************************************************************/
 230   /*                                                                       */
 231   /* <Type>                                                                */
 232   /*    FTC_Manager                                                        */
 233   /*                                                                       */
 234   /* <Description>                                                         */
 235   /*    This object corresponds to one instance of the cache-subsystem.    */
 236   /*    It is used to cache one or more @FT_Face objects, along with       */
 237   /*    corresponding @FT_Size objects.                                    */
 238   /*                                                                       */
 239   /*    The manager intentionally limits the total number of opened        */
 240   /*    @FT_Face and @FT_Size objects to control memory usage.  See the    */
 241   /*    `max_faces' and `max_sizes' parameters of @FTC_Manager_New.        */
 242   /*                                                                       */
 243   /*    The manager is also used to cache `nodes' of various types while   */
 244   /*    limiting their total memory usage.                                 */
 245   /*                                                                       */
 246   /*    All limitations are enforced by keeping lists of managed objects   */
 247   /*    in most-recently-used order, and flushing old nodes to make room   */
 248   /*    for new ones.                                                      */
 249   /*                                                                       */
 250   typedef struct FTC_ManagerRec_*  FTC_Manager;
 251
 252
 253   /*************************************************************************/
 254   /*                                                                       */
 255   /* <Type>                                                                */
 256   /*    FTC_Node                                                           */
 257   /*                                                                       */
 258   /* <Description>                                                         */
 259   /*    An opaque handle to a cache node object.  Each cache node is       */
 260   /*    reference-counted.  A node with a count of~0 might be flushed      */
 261   /*    out of a full cache whenever a lookup request is performed.        */
 262   /*                                                                       */
 263   /*    If you look up nodes, you have the ability to `acquire' them,      */
 264   /*    i.e., to increment their reference count.  This will prevent the   */
 265   /*    node from being flushed out of the cache until you explicitly      */
 266   /*    `release' it (see @FTC_Node_Unref).                                */
 267   /*                                                                       */
 268   /*    See also @FTC_SBitCache_Lookup and @FTC_ImageCache_Lookup.         */
 269   /*                                                                       */
 270   typedef struct FTC_NodeRec_*  FTC_Node;
 271
 272
 273   /*************************************************************************/
 274   /*                                                                       */
 275   /* <Function>                                                            */
 276   /*    FTC_Manager_New                                                    */
 277   /*                                                                       */
 278   /* <Description>                                                         */
 279   /*    Create a new cache manager.                                        */
 280   /*                                                                       */
 281   /* <Input>                                                               */
 282   /*    library   :: The parent FreeType library handle to use.            */
 283   /*                                                                       */
 284   /*    max_faces :: Maximum number of opened @FT_Face objects managed by  */
 285   /*                 this cache instance.  Use~0 for defaults.             */
 286   /*                                                                       */
 287   /*    max_sizes :: Maximum number of opened @FT_Size objects managed by  */
 288   /*                 this cache instance.  Use~0 for defaults.             */
 289   /*                                                                       */
 290   /*    max_bytes :: Maximum number of bytes to use for cached data nodes. */
 291   /*                 Use~0 for defaults.  Note that this value does not    */
 292   /*                 account for managed @FT_Face and @FT_Size objects.    */
 293   /*                                                                       */
 294   /*    requester :: An application-provided callback used to translate    */
 295   /*                 face IDs into real @FT_Face objects.                  */
 296   /*                                                                       */
 297   /*    req_data  :: A generic pointer that is passed to the requester     */
 298   /*                 each time it is called (see @FTC_Face_Requester).     */
 299   /*                                                                       */
 300   /* <Output>                                                              */
 301   /*    amanager  :: A handle to a new manager object.  0~in case of       */
 302   /*                 failure.                                              */
 303   /*                                                                       */
 304   /* <Return>                                                              */
 305   /*    FreeType error code.  0~means success.                             */
 306   /*                                                                       */
 307   FT_EXPORT( FT_Error )
 308   FTC_Manager_New( FT_Library          library,
 309                    FT_UInt             max_faces,
 310                    FT_UInt             max_sizes,
 311                    FT_ULong            max_bytes,
 312                    FTC_Face_Requester  requester,
 313                    FT_Pointer          req_data,
 314                    FTC_Manager        *amanager );
 315
 316
 317   /*************************************************************************/
 318   /*                                                                       */
 319   /* <Function>                                                            */
 320   /*    FTC_Manager_Reset                                                  */
 321   /*                                                                       */
 322   /* <Description>                                                         */
 323   /*    Empty a given cache manager.  This simply gets rid of all the      */
 324   /*    currently cached @FT_Face and @FT_Size objects within the manager. */
 325   /*                                                                       */
 326   /* <InOut>                                                               */
 327   /*    manager :: A handle to the manager.                                */
 328   /*                                                                       */
 329   FT_EXPORT( void )
 330   FTC_Manager_Reset( FTC_Manager  manager );
 331
 332
 333   /*************************************************************************/
 334   /*                                                                       */
 335   /* <Function>                                                            */
 336   /*    FTC_Manager_Done                                                   */
 337   /*                                                                       */
 338   /* <Description>                                                         */
 339   /*    Destroy a given manager after emptying it.                         */
 340   /*                                                                       */
 341   /* <Input>                                                               */
 342   /*    manager :: A handle to the target cache manager object.            */
 343   /*                                                                       */
 344   FT_EXPORT( void )
 345   FTC_Manager_Done( FTC_Manager  manager );
 346
 347
 348   /*************************************************************************/
 349   /*                                                                       */
 350   /* <Function>                                                            */
 351   /*    FTC_Manager_LookupFace                                             */
 352   /*                                                                       */
 353   /* <Description>                                                         */
 354   /*    Retrieve the @FT_Face object that corresponds to a given face ID   */
 355   /*    through a cache manager.                                           */
 356   /*                                                                       */
 357   /* <Input>                                                               */
 358   /*    manager :: A handle to the cache manager.                          */
 359   /*                                                                       */
 360   /*    face_id :: The ID of the face object.                              */
 361   /*                                                                       */
 362   /* <Output>                                                              */
 363   /*    aface   :: A handle to the face object.                            */
 364   /*                                                                       */
 365   /* <Return>                                                              */
 366   /*    FreeType error code.  0~means success.                             */
 367   /*                                                                       */
 368   /* <Note>                                                                */
 369   /*    The returned @FT_Face object is always owned by the manager.  You  */
 370   /*    should never try to discard it yourself.                           */
 371   /*                                                                       */
 372   /*    The @FT_Face object doesn't necessarily have a current size object */
 373   /*    (i.e., face->size can be~0).  If you need a specific `font size',  */
 374   /*    use @FTC_Manager_LookupSize instead.                               */
 375   /*                                                                       */
 376   /*    Never change the face's transformation matrix (i.e., never call    */
 377   /*    the @FT_Set_Transform function) on a returned face!  If you need   */
 378   /*    to transform glyphs, do it yourself after glyph loading.           */
 379   /*                                                                       */
 380   /*    When you perform a lookup, out-of-memory errors are detected       */
 381   /*    _within_ the lookup and force incremental flushes of the cache     */
 382   /*    until enough memory is released for the lookup to succeed.         */
 383   /*                                                                       */
 384   /*    If a lookup fails with `FT_Err_Out_Of_Memory' the cache has        */
 385   /*    already been completely flushed, and still no memory was available */
 386   /*    for the operation.                                                 */
 387   /*                                                                       */
 388   FT_EXPORT( FT_Error )
 389   FTC_Manager_LookupFace( FTC_Manager  manager,
 390                           FTC_FaceID   face_id,
 391                           FT_Face     *aface );
 392
 393
 394   /*************************************************************************/
 395   /*                                                                       */
 396   /* <Struct>                                                              */
 397   /*    FTC_ScalerRec                                                      */
 398   /*                                                                       */
 399   /* <Description>                                                         */
 400   /*    A structure used to describe a given character size in either      */
 401   /*    pixels or points to the cache manager.  See                        */
 402   /*    @FTC_Manager_LookupSize.                                           */
 403   /*                                                                       */
 404   /* <Fields>                                                              */
 405   /*    face_id :: The source face ID.                                     */
 406   /*                                                                       */
 407   /*    width   :: The character width.                                    */
 408   /*                                                                       */
 409   /*    height  :: The character height.                                   */
 410   /*                                                                       */
 411   /*    pixel   :: A Boolean.  If 1, the `width' and `height' fields are   */
 412   /*               interpreted as integer pixel character sizes.           */
 413   /*               Otherwise, they are expressed as 1/64th of points.      */
 414   /*                                                                       */
 415   /*    x_res   :: Only used when `pixel' is value~0 to indicate the       */
 416   /*               horizontal resolution in dpi.                           */
 417   /*                                                                       */
 418   /*    y_res   :: Only used when `pixel' is value~0 to indicate the       */
 419   /*               vertical resolution in dpi.                             */
 420   /*                                                                       */
 421   /* <Note>                                                                */
 422   /*    This type is mainly used to retrieve @FT_Size objects through the  */
 423   /*    cache manager.                                                     */
 424   /*                                                                       */
 425   typedef struct  FTC_ScalerRec_
 426   {
 427     FTC_FaceID  face_id;
 428     FT_UInt     width;
 429     FT_UInt     height;
 430     FT_Int      pixel;
 431     FT_UInt     x_res;
 432     FT_UInt     y_res;
 433
 434   } FTC_ScalerRec;
 435
 436
 437   /*************************************************************************/
 438   /*                                                                       */
 439   /* <Struct>                                                              */
 440   /*    FTC_Scaler                                                         */
 441   /*                                                                       */
 442   /* <Description>                                                         */
 443   /*    A handle to an @FTC_ScalerRec structure.                           */
 444   /*                                                                       */
 445   typedef struct FTC_ScalerRec_*  FTC_Scaler;
 446
 447
 448   /*************************************************************************/
 449   /*                                                                       */
 450   /* <Function>                                                            */
 451   /*    FTC_Manager_LookupSize                                             */
 452   /*                                                                       */
 453   /* <Description>                                                         */
 454   /*    Retrieve the @FT_Size object that corresponds to a given           */
 455   /*    @FTC_ScalerRec pointer through a cache manager.                    */
 456   /*                                                                       */
 457   /* <Input>                                                               */
 458   /*    manager :: A handle to the cache manager.                          */
 459   /*                                                                       */
 460   /*    scaler  :: A scaler handle.                                        */
 461   /*                                                                       */
 462   /* <Output>                                                              */
 463   /*    asize   :: A handle to the size object.                            */
 464   /*                                                                       */
 465   /* <Return>                                                              */
 466   /*    FreeType error code.  0~means success.                             */
 467   /*                                                                       */
 468   /* <Note>                                                                */
 469   /*    The returned @FT_Size object is always owned by the manager.  You  */
 470   /*    should never try to discard it by yourself.                        */
 471   /*                                                                       */
 472   /*    You can access the parent @FT_Face object simply as `size->face'   */
 473   /*    if you need it.  Note that this object is also owned by the        */
 474   /*    manager.                                                           */
 475   /*                                                                       */
 476   /* <Note>                                                                */
 477   /*    When you perform a lookup, out-of-memory errors are detected       */
 478   /*    _within_ the lookup and force incremental flushes of the cache     */
 479   /*    until enough memory is released for the lookup to succeed.         */
 480   /*                                                                       */
 481   /*    If a lookup fails with `FT_Err_Out_Of_Memory' the cache has        */
 482   /*    already been completely flushed, and still no memory is available  */
 483   /*    for the operation.                                                 */
 484   /*                                                                       */
 485   FT_EXPORT( FT_Error )
 486   FTC_Manager_LookupSize( FTC_Manager  manager,
 487                           FTC_Scaler   scaler,
 488                           FT_Size     *asize );
 489
 490
 491   /*************************************************************************/
 492   /*                                                                       */
 493   /* <Function>                                                            */
 494   /*    FTC_Node_Unref                                                     */
 495   /*                                                                       */
 496   /* <Description>                                                         */
 497   /*    Decrement a cache node's internal reference count.  When the count */
 498   /*    reaches 0, it is not destroyed but becomes eligible for subsequent */
 499   /*    cache flushes.                                                     */
 500   /*                                                                       */
 501   /* <Input>                                                               */
 502   /*    node    :: The cache node handle.                                  */
 503   /*                                                                       */
 504   /*    manager :: The cache manager handle.                               */
 505   /*                                                                       */
 506   FT_EXPORT( void )
 507   FTC_Node_Unref( FTC_Node     node,
 508                   FTC_Manager  manager );
 509
 510
 511   /*************************************************************************
 512    *
 513    * @function:
 514    *   FTC_Manager_RemoveFaceID
 515    *
 516    * @description:
 517    *   A special function used to indicate to the cache manager that
 518    *   a given @FTC_FaceID is no longer valid, either because its
 519    *   content changed, or because it was deallocated or uninstalled.
 520    *
 521    * @input:
 522    *   manager ::
 523    *     The cache manager handle.
 524    *
 525    *   face_id ::
 526    *     The @FTC_FaceID to be removed.
 527    *
 528    * @note:
 529    *   This function flushes all nodes from the cache corresponding to this
 530    *   `face_id', with the exception of nodes with a non-null reference
 531    *   count.
 532    *
 533    *   Such nodes are however modified internally so as to never appear
 534    *   in later lookups with the same `face_id' value, and to be immediately
 535    *   destroyed when released by all their users.
 536    *
 537    */
 538   FT_EXPORT( void )
 539   FTC_Manager_RemoveFaceID( FTC_Manager  manager,
 540                             FTC_FaceID   face_id );
 541
 542
 543   /*************************************************************************/
 544   /*                                                                       */
 545   /* <Section>                                                             */
 546   /*    cache_subsystem                                                    */
 547   /*                                                                       */
 548   /*************************************************************************/
 549
 550   /*************************************************************************
 551    *
 552    * @type:
 553    *   FTC_CMapCache
 554    *
 555    * @description:
 556    *   An opaque handle used to model a charmap cache.  This cache is to
 557    *   hold character codes -> glyph indices mappings.
 558    *
 559    */
 560   typedef struct FTC_CMapCacheRec_*  FTC_CMapCache;
 561
 562
 563   /*************************************************************************
 564    *
 565    * @function:
 566    *   FTC_CMapCache_New
 567    *
 568    * @description:
 569    *   Create a new charmap cache.
 570    *
 571    * @input:
 572    *   manager ::
 573    *     A handle to the cache manager.
 574    *
 575    * @output:
 576    *   acache ::
 577    *     A new cache handle.  NULL in case of error.
 578    *
 579    * @return:
 580    *   FreeType error code.  0~means success.
 581    *
 582    * @note:
 583    *   Like all other caches, this one will be destroyed with the cache
 584    *   manager.
 585    *
 586    */
 587   FT_EXPORT( FT_Error )
 588   FTC_CMapCache_New( FTC_Manager     manager,
 589                      FTC_CMapCache  *acache );
 590
 591
 592   /************************************************************************
 593    *
 594    * @function:
 595    *   FTC_CMapCache_Lookup
 596    *
 597    * @description:
 598    *   Translate a character code into a glyph index, using the charmap
 599    *   cache.
 600    *
 601    * @input:
 602    *   cache ::
 603    *     A charmap cache handle.
 604    *
 605    *   face_id ::
 606    *     The source face ID.
 607    *
 608    *   cmap_index ::
 609    *     The index of the charmap in the source face.  Any negative value
 610    *     means to use the cache @FT_Face's default charmap.
 611    *
 612    *   char_code ::
 613    *     The character code (in the corresponding charmap).
 614    *
 615    * @return:
 616    *    Glyph index.  0~means `no glyph'.
 617    *
 618    */
 619   FT_EXPORT( FT_UInt )
 620   FTC_CMapCache_Lookup( FTC_CMapCache  cache,
 621                         FTC_FaceID     face_id,
 622                         FT_Int         cmap_index,
 623                         FT_UInt32      char_code );
 624
 625
 626   /*************************************************************************/
 627   /*                                                                       */
 628   /* <Section>                                                             */
 629   /*    cache_subsystem                                                    */
 630   /*                                                                       */
 631   /*************************************************************************/
 632
 633
 634   /*************************************************************************/
 635   /*************************************************************************/
 636   /*************************************************************************/
 637   /*****                                                               *****/
 638   /*****                       IMAGE CACHE OBJECT                      *****/
 639   /*****                                                               *****/
 640   /*************************************************************************/
 641   /*************************************************************************/
 642   /*************************************************************************/
 643
 644
 645   /*************************************************************************
 646    *
 647    * @struct:
 648    *   FTC_ImageTypeRec
 649    *
 650    * @description:
 651    *   A structure used to model the type of images in a glyph cache.
 652    *
 653    * @fields:
 654    *   face_id ::
 655    *     The face ID.
 656    *
 657    *   width ::
 658    *     The width in pixels.
 659    *
 660    *   height ::
 661    *     The height in pixels.
 662    *
 663    *   flags ::
 664    *     The load flags, as in @FT_Load_Glyph.
 665    *
 666    */
 667   typedef struct  FTC_ImageTypeRec_
 668   {
 669     FTC_FaceID  face_id;
 670     FT_Int      width;
 671     FT_Int      height;
 672     FT_Int32    flags;
 673
 674   } FTC_ImageTypeRec;
 675
 676
 677   /*************************************************************************
 678    *
 679    * @type:
 680    *   FTC_ImageType
 681    *
 682    * @description:
 683    *   A handle to an @FTC_ImageTypeRec structure.
 684    *
 685    */
 686   typedef struct FTC_ImageTypeRec_*  FTC_ImageType;
 687
 688
 689   /* */
 690
 691
 692 #define FTC_IMAGE_TYPE_COMPARE( d1, d2 )      \
 693           ( (d1)->face_id == (d2)->face_id && \
 694             (d1)->width   == (d2)->width   && \
 695             (d1)->flags   == (d2)->flags   )
 696
 697
 698   /*************************************************************************/
 699   /*                                                                       */
 700   /* <Type>                                                                */
 701   /*    FTC_ImageCache                                                     */
 702   /*                                                                       */
 703   /* <Description>                                                         */
 704   /*    A handle to a glyph image cache object.  They are designed to      */
 705   /*    hold many distinct glyph images while not exceeding a certain      */
 706   /*    memory threshold.                                                  */
 707   /*                                                                       */
 708   typedef struct FTC_ImageCacheRec_*  FTC_ImageCache;
 709
 710
 711   /*************************************************************************/
 712   /*                                                                       */
 713   /* <Function>                                                            */
 714   /*    FTC_ImageCache_New                                                 */
 715   /*                                                                       */
 716   /* <Description>                                                         */
 717   /*    Create a new glyph image cache.                                    */
 718   /*                                                                       */
 719   /* <Input>                                                               */
 720   /*    manager :: The parent manager for the image cache.                 */
 721   /*                                                                       */
 722   /* <Output>                                                              */
 723   /*    acache  :: A handle to the new glyph image cache object.           */
 724   /*                                                                       */
 725   /* <Return>                                                              */
 726   /*    FreeType error code.  0~means success.                             */
 727   /*                                                                       */
 728   FT_EXPORT( FT_Error )
 729   FTC_ImageCache_New( FTC_Manager      manager,
 730                       FTC_ImageCache  *acache );
 731
 732
 733   /*************************************************************************/
 734   /*                                                                       */
 735   /* <Function>                                                            */
 736   /*    FTC_ImageCache_Lookup                                              */
 737   /*                                                                       */
 738   /* <Description>                                                         */
 739   /*    Retrieve a given glyph image from a glyph image cache.             */
 740   /*                                                                       */
 741   /* <Input>                                                               */
 742   /*    cache  :: A handle to the source glyph image cache.                */
 743   /*                                                                       */
 744   /*    type   :: A pointer to a glyph image type descriptor.              */
 745   /*                                                                       */
 746   /*    gindex :: The glyph index to retrieve.                             */
 747   /*                                                                       */
 748   /* <Output>                                                              */
 749   /*    aglyph :: The corresponding @FT_Glyph object.  0~in case of        */
 750   /*              failure.                                                 */
 751   /*                                                                       */
 752   /*    anode  :: Used to return the address of of the corresponding cache */
 753   /*              node after incrementing its reference count (see note    */
 754   /*              below).                                                  */
 755   /*                                                                       */
 756   /* <Return>                                                              */
 757   /*    FreeType error code.  0~means success.                             */
 758   /*                                                                       */
 759   /* <Note>                                                                */
 760   /*    The returned glyph is owned and managed by the glyph image cache.  */
 761   /*    Never try to transform or discard it manually!  You can however    */
 762   /*    create a copy with @FT_Glyph_Copy and modify the new one.          */
 763   /*                                                                       */
 764   /*    If `anode' is _not_ NULL, it receives the address of the cache     */
 765   /*    node containing the glyph image, after increasing its reference    */
 766   /*    count.  This ensures that the node (as well as the @FT_Glyph) will */
 767   /*    always be kept in the cache until you call @FTC_Node_Unref to      */
 768   /*    `release' it.                                                      */
 769   /*                                                                       */
 770   /*    If `anode' is NULL, the cache node is left unchanged, which means  */
 771   /*    that the @FT_Glyph could be flushed out of the cache on the next   */
 772   /*    call to one of the caching sub-system APIs.  Don't assume that it  */
 773   /*    is persistent!                                                     */
 774   /*                                                                       */
 775   FT_EXPORT( FT_Error )
 776   FTC_ImageCache_Lookup( FTC_ImageCache  cache,
 777                          FTC_ImageType   type,
 778                          FT_UInt         gindex,
 779                          FT_Glyph       *aglyph,
 780                          FTC_Node       *anode );
 781
 782
 783   /*************************************************************************/
 784   /*                                                                       */
 785   /* <Function>                                                            */
 786   /*    FTC_ImageCache_LookupScaler                                        */
 787   /*                                                                       */
 788   /* <Description>                                                         */
 789   /*    A variant of @FTC_ImageCache_Lookup that uses an @FTC_ScalerRec    */
 790   /*    to specify the face ID and its size.                               */
 791   /*                                                                       */
 792   /* <Input>                                                               */
 793   /*    cache      :: A handle to the source glyph image cache.            */
 794   /*                                                                       */
 795   /*    scaler     :: A pointer to a scaler descriptor.                    */
 796   /*                                                                       */
 797   /*    load_flags :: The corresponding load flags.                        */
 798   /*                                                                       */
 799   /*    gindex     :: The glyph index to retrieve.                         */
 800   /*                                                                       */
 801   /* <Output>                                                              */
 802   /*    aglyph     :: The corresponding @FT_Glyph object.  0~in case of    */
 803   /*                  failure.                                             */
 804   /*                                                                       */
 805   /*    anode      :: Used to return the address of of the corresponding   */
 806   /*                  cache node after incrementing its reference count    */
 807   /*                  (see note below).                                    */
 808   /*                                                                       */
 809   /* <Return>                                                              */
 810   /*    FreeType error code.  0~means success.                             */
 811   /*                                                                       */
 812   /* <Note>                                                                */
 813   /*    The returned glyph is owned and managed by the glyph image cache.  */
 814   /*    Never try to transform or discard it manually!  You can however    */
 815   /*    create a copy with @FT_Glyph_Copy and modify the new one.          */
 816   /*                                                                       */
 817   /*    If `anode' is _not_ NULL, it receives the address of the cache     */
 818   /*    node containing the glyph image, after increasing its reference    */
 819   /*    count.  This ensures that the node (as well as the @FT_Glyph) will */
 820   /*    always be kept in the cache until you call @FTC_Node_Unref to      */
 821   /*    `release' it.                                                      */
 822   /*                                                                       */
 823   /*    If `anode' is NULL, the cache node is left unchanged, which means  */
 824   /*    that the @FT_Glyph could be flushed out of the cache on the next   */
 825   /*    call to one of the caching sub-system APIs.  Don't assume that it  */
 826   /*    is persistent!                                                     */
 827   /*                                                                       */
 828   /*    Calls to @FT_Set_Char_Size and friends have no effect on cached    */
 829   /*    glyphs; you should always use the FreeType cache API instead.      */
 830   /*                                                                       */
 831   FT_EXPORT( FT_Error )
 832   FTC_ImageCache_LookupScaler( FTC_ImageCache  cache,
 833                                FTC_Scaler      scaler,
 834                                FT_ULong        load_flags,
 835                                FT_UInt         gindex,
 836                                FT_Glyph       *aglyph,
 837                                FTC_Node       *anode );
 838
 839
 840   /*************************************************************************/
 841   /*                                                                       */
 842   /* <Type>                                                                */
 843   /*    FTC_SBit                                                           */
 844   /*                                                                       */
 845   /* <Description>                                                         */
 846   /*    A handle to a small bitmap descriptor.  See the @FTC_SBitRec       */
 847   /*    structure for details.                                             */
 848   /*                                                                       */
 849   typedef struct FTC_SBitRec_*  FTC_SBit;
 850
 851
 852   /*************************************************************************/
 853   /*                                                                       */
 854   /* <Struct>                                                              */
 855   /*    FTC_SBitRec                                                        */
 856   /*                                                                       */
 857   /* <Description>                                                         */
 858   /*    A very compact structure used to describe a small glyph bitmap.    */
 859   /*                                                                       */
 860   /* <Fields>                                                              */
 861   /*    width     :: The bitmap width in pixels.                           */
 862   /*                                                                       */
 863   /*    height    :: The bitmap height in pixels.                          */
 864   /*                                                                       */
 865   /*    left      :: The horizontal distance from the pen position to the  */
 866   /*                 left bitmap border (a.k.a. `left side bearing', or    */
 867   /*                 `lsb').                                               */
 868   /*                                                                       */
 869   /*    top       :: The vertical distance from the pen position (on the   */
 870   /*                 baseline) to the upper bitmap border (a.k.a. `top     */
 871   /*                 side bearing').  The distance is positive for upwards */
 872   /*                 y~coordinates.                                        */
 873   /*                                                                       */
 874   /*    format    :: The format of the glyph bitmap (monochrome or gray).  */
 875   /*                                                                       */
 876   /*    max_grays :: Maximum gray level value (in the range 1 to~255).     */
 877   /*                                                                       */
 878   /*    pitch     :: The number of bytes per bitmap line.  May be positive */
 879   /*                 or negative.                                          */
 880   /*                                                                       */
 881   /*    xadvance  :: The horizontal advance width in pixels.               */
 882   /*                                                                       */
 883   /*    yadvance  :: The vertical advance height in pixels.                */
 884   /*                                                                       */
 885   /*    buffer    :: A pointer to the bitmap pixels.                       */
 886   /*                                                                       */
 887   typedef struct  FTC_SBitRec_
 888   {
 889     FT_Byte   width;
 890     FT_Byte   height;
 891     FT_Char   left;
 892     FT_Char   top;
 893
 894     FT_Byte   format;
 895     FT_Byte   max_grays;
 896     FT_Short  pitch;
 897     FT_Char   xadvance;
 898     FT_Char   yadvance;
 899
 900     FT_Byte*  buffer;
 901
 902   } FTC_SBitRec;
 903
 904
 905   /*************************************************************************/
 906   /*                                                                       */
 907   /* <Type>                                                                */
 908   /*    FTC_SBitCache                                                      */
 909   /*                                                                       */
 910   /* <Description>                                                         */
 911   /*    A handle to a small bitmap cache.  These are special cache objects */
 912   /*    used to store small glyph bitmaps (and anti-aliased pixmaps) in a  */
 913   /*    much more efficient way than the traditional glyph image cache     */
 914   /*    implemented by @FTC_ImageCache.                                    */
 915   /*                                                                       */
 916   typedef struct FTC_SBitCacheRec_*  FTC_SBitCache;
 917
 918
 919   /*************************************************************************/
 920   /*                                                                       */
 921   /* <Function>                                                            */
 922   /*    FTC_SBitCache_New                                                  */
 923   /*                                                                       */
 924   /* <Description>                                                         */
 925   /*    Create a new cache to store small glyph bitmaps.                   */
 926   /*                                                                       */
 927   /* <Input>                                                               */
 928   /*    manager :: A handle to the source cache manager.                   */
 929   /*                                                                       */
 930   /* <Output>                                                              */
 931   /*    acache  :: A handle to the new sbit cache.  NULL in case of error. */
 932   /*                                                                       */
 933   /* <Return>                                                              */
 934   /*    FreeType error code.  0~means success.                             */
 935   /*                                                                       */
 936   FT_EXPORT( FT_Error )
 937   FTC_SBitCache_New( FTC_Manager     manager,
 938                      FTC_SBitCache  *acache );
 939
 940
 941   /*************************************************************************/
 942   /*                                                                       */
 943   /* <Function>                                                            */
 944   /*    FTC_SBitCache_Lookup                                               */
 945   /*                                                                       */
 946   /* <Description>                                                         */
 947   /*    Look up a given small glyph bitmap in a given sbit cache and       */
 948   /*    `lock' it to prevent its flushing from the cache until needed.     */
 949   /*                                                                       */
 950   /* <Input>                                                               */
 951   /*    cache  :: A handle to the source sbit cache.                       */
 952   /*                                                                       */
 953   /*    type   :: A pointer to the glyph image type descriptor.            */
 954   /*                                                                       */
 955   /*    gindex :: The glyph index.                                         */
 956   /*                                                                       */
 957   /* <Output>                                                              */
 958   /*    sbit   :: A handle to a small bitmap descriptor.                   */
 959   /*                                                                       */
 960   /*    anode  :: Used to return the address of of the corresponding cache */
 961   /*              node after incrementing its reference count (see note    */
 962   /*              below).                                                  */
 963   /*                                                                       */
 964   /* <Return>                                                              */
 965   /*    FreeType error code.  0~means success.                             */
 966   /*                                                                       */
 967   /* <Note>                                                                */
 968   /*    The small bitmap descriptor and its bit buffer are owned by the    */
 969   /*    cache and should never be freed by the application.  They might    */
 970   /*    as well disappear from memory on the next cache lookup, so don't   */
 971   /*    treat them as persistent data.                                     */
 972   /*                                                                       */
 973   /*    The descriptor's `buffer' field is set to~0 to indicate a missing  */
 974   /*    glyph bitmap.                                                      */
 975   /*                                                                       */
 976   /*    If `anode' is _not_ NULL, it receives the address of the cache     */
 977   /*    node containing the bitmap, after increasing its reference count.  */
 978   /*    This ensures that the node (as well as the image) will always be   */
 979   /*    kept in the cache until you call @FTC_Node_Unref to `release' it.  */
 980   /*                                                                       */
 981   /*    If `anode' is NULL, the cache node is left unchanged, which means  */
 982   /*    that the bitmap could be flushed out of the cache on the next      */
 983   /*    call to one of the caching sub-system APIs.  Don't assume that it  */
 984   /*    is persistent!                                                     */
 985   /*                                                                       */
 986   FT_EXPORT( FT_Error )
 987   FTC_SBitCache_Lookup( FTC_SBitCache    cache,
 988                         FTC_ImageType    type,
 989                         FT_UInt          gindex,
 990                         FTC_SBit        *sbit,
 991                         FTC_Node        *anode );
 992
 993
 994   /*************************************************************************/
 995   /*                                                                       */
 996   /* <Function>                                                            */
 997   /*    FTC_SBitCache_LookupScaler                                         */
 998   /*                                                                       */
 999   /* <Description>                                                         */
1000   /*    A variant of @FTC_SBitCache_Lookup that uses an @FTC_ScalerRec     */
1001   /*    to specify the face ID and its size.                               */
1002   /*                                                                       */
1003   /* <Input>                                                               */
1004   /*    cache      :: A handle to the source sbit cache.                   */
1005   /*                                                                       */
1006   /*    scaler     :: A pointer to the scaler descriptor.                  */
1007   /*                                                                       */
1008   /*    load_flags :: The corresponding load flags.                        */
1009   /*                                                                       */
1010   /*    gindex     :: The glyph index.                                     */
1011   /*                                                                       */
1012   /* <Output>                                                              */
1013   /*    sbit       :: A handle to a small bitmap descriptor.               */
1014   /*                                                                       */
1015   /*    anode      :: Used to return the address of of the corresponding   */
1016   /*                  cache node after incrementing its reference count    */
1017   /*                  (see note below).                                    */
1018   /*                                                                       */
1019   /* <Return>                                                              */
1020   /*    FreeType error code.  0~means success.                             */
1021   /*                                                                       */
1022   /* <Note>                                                                */
1023   /*    The small bitmap descriptor and its bit buffer are owned by the    */
1024   /*    cache and should never be freed by the application.  They might    */
1025   /*    as well disappear from memory on the next cache lookup, so don't   */
1026   /*    treat them as persistent data.                                     */
1027   /*                                                                       */
1028   /*    The descriptor's `buffer' field is set to~0 to indicate a missing  */
1029   /*    glyph bitmap.                                                      */
1030   /*                                                                       */
1031   /*    If `anode' is _not_ NULL, it receives the address of the cache     */
1032   /*    node containing the bitmap, after increasing its reference count.  */
1033   /*    This ensures that the node (as well as the image) will always be   */
1034   /*    kept in the cache until you call @FTC_Node_Unref to `release' it.  */
1035   /*                                                                       */
1036   /*    If `anode' is NULL, the cache node is left unchanged, which means  */
1037   /*    that the bitmap could be flushed out of the cache on the next      */
1038   /*    call to one of the caching sub-system APIs.  Don't assume that it  */
1039   /*    is persistent!                                                     */
1040   /*                                                                       */
1041   FT_EXPORT( FT_Error )
1042   FTC_SBitCache_LookupScaler( FTC_SBitCache  cache,
1043                               FTC_Scaler     scaler,
1044                               FT_ULong       load_flags,
1045                               FT_UInt        gindex,
1046                               FTC_SBit      *sbit,
1047                               FTC_Node      *anode );
1048
1049   /* */
1050
1051
1052 FT_END_HEADER
1053
1054 #endif /* __FTCACHE_H__ */
1055
1056
1057 /* END */