shithub: freetype+ttf2subf

ref: 0f15e1c181521eb1cc755a83fa4bcbe97b60ad00
dir: /include/freetype/ftcache.h/

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/***************************************************************************/
/*                                                                         */
/*  ftcache.h                                                              */
/*                                                                         */
/*    FreeType Cache subsystem (specification).                            */
/*                                                                         */
/*  Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006 by                   */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/


#ifndef __FTCACHE_H__
#define __FTCACHE_H__


#include <ft2build.h>
#include FT_GLYPH_H


FT_BEGIN_HEADER


  /*************************************************************************
   *
   * <Section>
   *    cache_subsystem
   *
   * <Title>
   *    Cache Sub-System
   *
   * <Abstract>
   *    How to cache face, size, and glyph data with FreeType 2.
   *
   * <Description>
   *   This section describes the FreeType 2 cache sub-system, which is used
   *   to limit the number of concurrently opened @FT_Face and @FT_Size
   *   objects, as well as caching information like character maps and glyph
   *   images while limiting their maximum memory usage.
   *
   *   Note that all types and functions begin with the FTC_ prefix.
   *
   *   the cache is highly portable and thus doesn't know anything about
   *   the fonts installed on your system, or how to access them. This implies
   *   the following scheme:
   *
   *   first, available/installed font faces are uniquely identified by
   *   @FTC_FaceID values provided to the cache by the client. Note that the
   *   cache only stores and compares these values, and doesn't try to
   *   interpret them in any way.
   *
   *   Second, the cache will call, only when needed, a client-provided
   *   function to convert a @FTC_FaceID into a new @FT_Face object. The latter
   *   will then be completely managed by the cache, including its termination
   *   through @FT_Done_Face.
   *
   *   Clients are free to map face ids to anything. The most simple usage is
   *   to associate them to a (pathname,face_index) pair that is used to call
   *   @FT_New_Face. However, more complex schemes are also possible.
   *
   *   Note that for the cache to work correctly, the face id values must be
   *   *persistent*, which means that the content they point to should not
   *   change at runtime, or that their value should not become invalid.
   *
   *   If this is unavoidable (e.g. when a font is uninstalled at runtime),
   *   you should call @FTC_Manager_RemoveFaceID as soon as possible, to let
   *   the cache get rid of any references to the old @FTC_FaceID it may
   *   keep internally. Failure to do so will lead to incorrect behaviour
   *   or even crashes.
   *
   *   To use the cache, start by calling @FTC_Manager_New to create a new
   *   @FTC_Manager object, which models a single cache instance. You can
   *   then lookup @FT_Face and @FT_Size objects with @FTC_Manager_LookupFace
   *   and @FTC_Manager_LookupSize respectively.
   *
   *   If you want to use the charmap caching, call @FTC_CMapCache_New, then
   *   later use @FTC_CMapCache_Lookup to perform the equivalent of
   *   @FT_Get_Char_Index, only much faster.
   *
   *   If you want to use the @FT_Glyph caching, call @FTC_ImageCache, then
   *   later use @FTC_ImageCache_Lookup to retrieve the corresponding
   *   @FT_Glyph objects from the cache.
   *
   *   If you need lots of small bitmaps, it is much more memory efficient to
   *   call @FTC_SBitCache_New, then later @FTC_SBitCache_Lookup, this returns
   *   @FTC_SBitRec structures, which are used to store small bitmaps directly.
   *   (a small bitmap is one whose metrics and dimensions all fit in 8-bit
   *   integers).
   *
   *   We hope to also provide a kerning cache in the near future. Stay
   *   tuned.
   *
   *
   * <Order>
   *   FTC_Manager
   *   FTC_FaceID
   *   FTC_Face_Requester
   *
   *   FTC_Manager_New
   *   FTC_Manager_Reset
   *   FTC_Manager_Done
   *   FTC_Manager_LookupFace
   *   FTC_Manager_LookupSize
   *   FTC_Manager_RemoveFaceID
   *
   *   FTC_Node
   *   FTC_Node_Unref
   *
   *   FTC_ImageCache
   *   FTC_ImageCache_New
   *   FTC_ImageCache_Lookup
   *
   *   FTC_SBit
   *   FTC_SBitCache
   *   FTC_SBitCache_New
   *   FTC_SBitCache_Lookup
   *
   *   FTC_CMapCache
   *   FTC_CMapCache_New
   *   FTC_CMapCache_Lookup
   *
   *************************************************************************/


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                    BASIC TYPE DEFINITIONS                     *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


 /*************************************************************************
  *
  * @type: FTC_FaceID
  *
  * @description:
  *    An opaque pointer type that is used to identity face objects.  The
  *    contents of such objects is application-dependent.
  *
  *    these pointers are typically used to point to a user-defined
  *    structure containing a font file path, and face index.
  *
  * @note:
  *    never use NULL as a valid @FTC_FaceID
  *
  *    Face ids are passed by the client to the cache manager, which will
  *    call, when needed, the @FTC_Face_Requester to translate them into
  *    new @FT_Face objects
  *
  *    if the content of a given face id changes at runtime, or if the
  *    value becomes invalid (e.g. when uninstalling a font), you should
  *    immediately call @FTC_Manager_RemoveFaceID before any other cache
  *    function.
  *
  *    Failure to do so will result in incorrect behaviour or even
  *    memory leaks and crashes !
  **/
  typedef struct FTC_FaceIDRec_*  FTC_FaceID;


 /************************************************************************
  *
  * @functype: FTC_Face_Requester
  *
  * @description:
  *    A callback function provided by client applications.  It is used
  *    by the cache manager to translate a given @FTC_FaceID into a new
  *    valid @FT_Face object, on demand.
  *
  * <Input>
  *    face_id  :: The face ID to resolve.
  *
  *    library  :: A handle to a FreeType library object.
  *
  *    req_data :: Application-provided request data (see note below).
  *
  * <Output>
  *    aface   :: A new @FT_Face handle.
  *
  * <Return>
  *    FreeType error code.  0 means success.
  *
  * <Note>
  *    The third parameter 'req_data' is the same than the one passed
  *    by the client when @FTC_Manager_New is called.
  *
  *    The face requester should not perform funny things on the returned
  *    face object, like creating a new @FT_Size for it, or setting a
  *    transformation through @FT_Set_Transform!
  **/
  typedef FT_Error
  (*FTC_Face_Requester)( FTC_FaceID  face_id,
                         FT_Library  library,
                         FT_Pointer  request_data,
                         FT_Face*    aface );

 /* */

#define FT_POINTER_TO_ULONG( p )  ( (FT_ULong)(FT_Pointer)(p) )

#define FTC_FACE_ID_HASH( i )                                \
          ((FT_UInt32)(( FT_POINTER_TO_ULONG( i ) >> 3 ) ^   \
                       ( FT_POINTER_TO_ULONG( i ) << 7 ) ) )


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                      CACHE MANAGER OBJECT                     *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FTC_Manager                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    This object corresponds to one instance of the cache-subsystem.    */
  /*    It is used to cache one or more @FT_Face objects, along with       */
  /*    corresponding @FT_Size objects.                                    */
  /*                                                                       */
  /*    the manager intentionally limits the total number of opened        */
  /*    @FT_Face and @FT_Size objects to limit memory usage. See the       */
  /*    'max_faces' and 'max_sizes' parameters of @FTC_Manager_New.        */
  /*                                                                       */
  /*    the manager is also used to cache 'nodes' of various types         */
  /*    while limiting their total memory usage.                           */
  /*                                                                       */
  /*    All limitations are enforced by keeping lists of managed objects   */
  /*    in most-recently-used order, and flushing old nodes to make room   */
  /*    for new ones.                                                      */
  /*                                                                       */
  typedef struct FTC_ManagerRec_*  FTC_Manager;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FTC_Node                                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    An opaque handle to a cache node object.  Each cache node is       */
  /*    reference-counted.  A node with a count of 0 might be flushed      */
  /*    out of a full cache whenever a lookup request is performed.        */
  /*                                                                       */
  /*    If you lookup nodes, you have the ability to `acquire' them, i.e., */
  /*    to increment their reference count.  This will prevent the node    */
  /*    from being flushed out of the cache until you explicitly `release' */
  /*    it (see @FTC_Node_Unref).                                          */
  /*                                                                       */
  /*    See also @FTC_SBitCache_Lookup and @FTC_ImageCache_Lookup.         */
  /*                                                                       */
  typedef struct FTC_NodeRec_*  FTC_Node;


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Manager_New                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Creates a new cache manager.                                       */
  /*                                                                       */
  /* <Input>                                                               */
  /*    library     :: The parent FreeType library handle to use.          */
  /*                                                                       */
  /*    max_faces   :: Maximum number of opened @FT_Face objects managed   */
  /*                   by this cache instance.                             */
  /*                                                                       */
  /*    max_sizes   :: Maximum number of opened @FT_Size objects managed   */
  /*                   by this cache instance.                             */
  /*                                                                       */
  /*    max_bytes   :: Maximum number of bytes to use for cached data      */
  /*                   nodes.  Use 0 for defaults.  Note that this value   */
  /*                   does not account for managed FT_Face and FT_Size    */
  /*                   objects.                                            */
  /*                                                                       */
  /*    requester   :: An application-provided callback used to translate  */
  /*                   face IDs into real @FT_Face objects.                */
  /*                                                                       */
  /*    req_data    :: A generic pointer that is passed to the requester   */
  /*                   each time it is called (see @FTC_Face_Requester).   */
  /*                                                                       */
  /* <Output>                                                              */
  /*    amanager  :: A handle to a new manager object.  0 in case of       */
  /*                 failure.                                              */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_Manager_New( FT_Library          library,
                   FT_UInt             max_faces,
                   FT_UInt             max_sizes,
                   FT_ULong            max_bytes,
                   FTC_Face_Requester  requester,
                   FT_Pointer          req_data,
                   FTC_Manager        *amanager );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Manager_Reset                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Empties a given cache manager.  This simply gets rid of all the    */
  /*    currently cached @FT_Face and @FT_Size objects within the manager. */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    manager :: A handle to the manager.                                */
  /*                                                                       */
  FT_EXPORT( void )
  FTC_Manager_Reset( FTC_Manager  manager );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Manager_Done                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Destroys a given manager after emptying it.                        */
  /*                                                                       */
  /* <Input>                                                               */
  /*    manager :: A handle to the target cache manager object.            */
  /*                                                                       */
  FT_EXPORT( void )
  FTC_Manager_Done( FTC_Manager  manager );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Manager_LookupFace                                             */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Retrieves the @FT_Face object that corresponds to a given face ID  */
  /*    through a cache manager.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    manager :: A handle to the cache manager.                          */
  /*                                                                       */
  /*    face_id :: The ID of the face object.                              */
  /*                                                                       */
  /* <Output>                                                              */
  /*    aface   :: A handle to the face object.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The returned @FT_Face object is always owned by the manager.  You  */
  /*    should never try to discard it yourself.                           */
  /*                                                                       */
  /*    The @FT_Face object doesn't necessarily have a current size object */
  /*    (i.e., face->size can be 0).  If you need a specific `font size',  */
  /*    use @FTC_Manager_LookupSize instead.                               */
  /*                                                                       */
  /*    Never change the face's transformation matrix (i.e., never call    */
  /*    the @FT_Set_Transform function) on a returned face!  If you need   */
  /*    to transform glyphs, do it yourself after glyph loading.           */
  /*                                                                       */
  /* <Note>                                                                */
  /*    When you perform a lookup, out-of-memory errors are detected       */
  /*    _within_ the lookup and force incremental flushes of the cache     */
  /*    until enough memory is released for the lookup to succeed.         */
  /*                                                                       */
  /*    If a lookup fails with FT_Err_Out_Of_Memory the cache has already  */
  /*    been completely flushed, and still no memory is available for the  */
  /*    operation.                                                         */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_Manager_LookupFace( FTC_Manager  manager,
                          FTC_FaceID   face_id,
                          FT_Face     *aface );


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FTC_ScalerRec                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A structure used to describe a given character size in either      */
  /*    pixels or points to the cache manager.  See                        */
  /*    @FTC_Manager_LookupSize.                                           */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    face_id :: The source face ID.                                     */
  /*                                                                       */
  /*    width   :: The character width.                                    */
  /*                                                                       */
  /*    height  :: The character height.                                   */
  /*                                                                       */
  /*    pixel   :: A Boolean.  If TRUE, the `width' and `height' fields    */
  /*               are interpreted as integer pixel character sizes.       */
  /*               Otherwise, they are expressed as 1/64th of points.      */
  /*                                                                       */
  /*    x_res   :: Only used when `pixel' is FALSE to indicate the         */
  /*               horizontal resolution in dpi.                           */
  /*                                                                       */
  /*    y_res   :: Only used when `pixel' is FALSE to indicate the         */
  /*               vertical resolution in dpi.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This type is mainly used to retrieve @FT_Size objects through the  */
  /*    cache manager.                                                     */
  /*                                                                       */
  typedef struct  FTC_ScalerRec_
  {
    FTC_FaceID  face_id;
    FT_UInt     width;
    FT_UInt     height;
    FT_Int      pixel;
    FT_UInt     x_res;
    FT_UInt     y_res;

  } FTC_ScalerRec, *FTC_Scaler;


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Manager_LookupSize                                             */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Retrieve the @FT_Size object that corresponds to a given           */
  /*    @FTC_Scaler through a cache manager.                               */
  /*                                                                       */
  /* <Input>                                                               */
  /*    manager :: A handle to the cache manager.                          */
  /*                                                                       */
  /*    scaler  :: A scaler handle.                                        */
  /*                                                                       */
  /* <Output>                                                              */
  /*    asize   :: A handle to the size object.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The returned @FT_Size object is always owned by the manager.  You  */
  /*    should never try to discard it by yourself.                        */
  /*                                                                       */
  /*    You can access the parent @FT_Face object simply as `size->face'   */
  /*    if you need it.  Note that this object is also owned by the        */
  /*    manager.                                                           */
  /*                                                                       */
  /* <Note>                                                                */
  /*    When you perform a lookup, out-of-memory errors are detected       */
  /*    _within_ the lookup and force incremental flushes of the cache     */
  /*    until enough memory is released for the lookup to succeed.         */
  /*                                                                       */
  /*    If a lookup fails with FT_Err_Out_Of_Memory the cache has already  */
  /*    been completely flushed, and still no memory is available for the  */
  /*    operation.                                                         */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_Manager_LookupSize( FTC_Manager  manager,
                          FTC_Scaler   scaler,
                          FT_Size     *asize );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_Node_Unref                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Decrement a cache node's internal reference count.  When the count */
  /*    reaches 0, it is not destroyed but becomes eligible for subsequent */
  /*    cache flushes.                                                     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    node    :: The cache node handle.                                  */
  /*                                                                       */
  /*    manager :: The cache manager handle.                               */
  /*                                                                       */
  FT_EXPORT( void )
  FTC_Node_Unref( FTC_Node     node,
                  FTC_Manager  manager );


  /* remove all nodes belonging to a given face_id */
  FT_EXPORT( void )
  FTC_Manager_RemoveFaceID( FTC_Manager  manager,
                            FTC_FaceID   face_id );


  /*************************************************************************/
  /*                                                                       */
  /* <Section>                                                             */
  /*    cache_subsystem                                                    */
  /*                                                                       */
  /*************************************************************************/

  /*************************************************************************
   *
   * @type:
   *   FTC_CMapCache
   *
   * @description:
   *   An opaque handle used to manager a charmap cache.  This cache is to
   *   hold character codes -> glyph indices mappings.
   *
   */
  typedef struct FTC_CMapCacheRec_*  FTC_CMapCache;


  /*************************************************************************
   *
   * @function:
   *   FTC_CMapCache_New
   *
   * @description:
   *   Create a new charmap cache.
   *
   * @input:
   *   manager ::
   *     A handle to the cache manager.
   *
   * @output:
   *   acache ::
   *     A new cache handle.  NULL in case of error.
   *
   * @return:
   *   FreeType error code.  0 means success.
   *
   * @note:
   *   Like all other caches, this one will be destroyed with the cache
   *   manager.
   *
   */
  FT_EXPORT( FT_Error )
  FTC_CMapCache_New( FTC_Manager     manager,
                     FTC_CMapCache  *acache );


  /************************************************************************
   *
   * @function:
   *   FTC_CMapCache_Lookup
   *
   * @description:
   *   Translate a character code into a glyph index, using the charmap
   *   cache.
   *
   * @input:
   *   cache ::
   *     A charmap cache handle.
   *
   *   face_id ::
   *     The source face ID.
   *
   *   cmap_index ::
   *     The index of the charmap in the source face.
   *
   *   char_code ::
   *     The character code (in the corresponding charmap).
   *
   * @return:
   *    Glyph index.  0 means `no glyph'.
   *
   */
  FT_EXPORT( FT_UInt )
  FTC_CMapCache_Lookup( FTC_CMapCache  cache,
                        FTC_FaceID     face_id,
                        FT_Int         cmap_index,
                        FT_UInt32      char_code );


  /*************************************************************************/
  /*                                                                       */
  /* <Section>                                                             */
  /*    cache_subsystem                                                    */
  /*                                                                       */
  /*************************************************************************/


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                       IMAGE CACHE OBJECT                      *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/

  typedef struct  FTC_ImageTypeRec_
  {
    FTC_FaceID  face_id;
    FT_Int      width;
    FT_Int      height;
    FT_Int32    flags;

  } FTC_ImageTypeRec;

  typedef struct FTC_ImageTypeRec_*  FTC_ImageType;


  /* */


#define FTC_IMAGE_TYPE_COMPARE( d1, d2 )      \
          ( (d1)->face_id == (d2)->face_id && \
            (d1)->width   == (d2)->width   && \
            (d1)->flags   == (d2)->flags   )

#define FTC_IMAGE_TYPE_HASH( d )                          \
          (FT_UFast)( FTC_FACE_ID_HASH( (d)->face_id )  ^ \
                      ( (d)->width << 8 ) ^ (d)->height ^ \
                      ( (d)->flags << 4 )               )


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FTC_ImageCache                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to an glyph image cache object.  They are designed to     */
  /*    hold many distinct glyph images while not exceeding a certain      */
  /*    memory threshold.                                                  */
  /*                                                                       */
  typedef struct FTC_ImageCacheRec_*  FTC_ImageCache;


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_ImageCache_New                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Creates a new glyph image cache.                                   */
  /*                                                                       */
  /* <Input>                                                               */
  /*    manager :: The parent manager for the image cache.                 */
  /*                                                                       */
  /* <Output>                                                              */
  /*    acache  :: A handle to the new glyph image cache object.           */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_ImageCache_New( FTC_Manager      manager,
                      FTC_ImageCache  *acache );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_ImageCache_Lookup                                              */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Retrieves a given glyph image from a glyph image cache.            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    cache  :: A handle to the source glyph image cache.                */
  /*                                                                       */
  /*    type   :: A pointer to a glyph image type descriptor.              */
  /*                                                                       */
  /*    gindex :: The glyph index to retrieve.                             */
  /*                                                                       */
  /* <Output>                                                              */
  /*    aglyph :: The corresponding @FT_Glyph object.  0 in case of        */
  /*              failure.                                                 */
  /*                                                                       */
  /*    anode  :: Used to return the address of of the corresponding cache */
  /*              node after incrementing its reference count (see note    */
  /*              below).                                                  */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The returned glyph is owned and managed by the glyph image cache.  */
  /*    Never try to transform or discard it manually!  You can however    */
  /*    create a copy with @FT_Glyph_Copy and modify the new one.          */
  /*                                                                       */
  /*    If `anode' is _not_ NULL, it receives the address of the cache     */
  /*    node containing the glyph image, after increasing its reference    */
  /*    count.  This ensures that the node (as well as the FT_Glyph) will  */
  /*    always be kept in the cache until you call @FTC_Node_Unref to      */
  /*    `release' it.                                                      */
  /*                                                                       */
  /*    If `anode' is NULL, the cache node is left unchanged, which means  */
  /*    that the FT_Glyph could be flushed out of the cache on the next    */
  /*    call to one of the caching sub-system APIs.  Don't assume that it  */
  /*    is persistent!                                                     */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_ImageCache_Lookup( FTC_ImageCache  cache,
                         FTC_ImageType   type,
                         FT_UInt         gindex,
                         FT_Glyph       *aglyph,
                         FTC_Node       *anode );


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FTC_SBit                                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a small bitmap descriptor.  See the @FTC_SBitRec       */
  /*    structure for details.                                             */
  /*                                                                       */
  typedef struct FTC_SBitRec_*  FTC_SBit;


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FTC_SBitRec                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A very compact structure used to describe a small glyph bitmap.    */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    width     :: The bitmap width in pixels.                           */
  /*                                                                       */
  /*    height    :: The bitmap height in pixels.                          */
  /*                                                                       */
  /*    left      :: The horizontal distance from the pen position to the  */
  /*                 left bitmap border (a.k.a. `left side bearing', or    */
  /*                 `lsb').                                               */
  /*                                                                       */
  /*    top       :: The vertical distance from the pen position (on the   */
  /*                 baseline) to the upper bitmap border (a.k.a. `top     */
  /*                 side bearing').  The distance is positive for upwards */
  /*                 Y coordinates.                                        */
  /*                                                                       */
  /*    format    :: The format of the glyph bitmap (monochrome or gray).  */
  /*                                                                       */
  /*    max_grays :: Maximum gray level value (in the range 1 to 255).     */
  /*                                                                       */
  /*    pitch     :: The number of bytes per bitmap line.  May be positive */
  /*                 or negative.                                          */
  /*                                                                       */
  /*    xadvance  :: The horizontal advance width in pixels.               */
  /*                                                                       */
  /*    yadvance  :: The vertical advance height in pixels.                */
  /*                                                                       */
  /*    buffer    :: A pointer to the bitmap pixels.                       */
  /*                                                                       */
  typedef struct  FTC_SBitRec_
  {
    FT_Byte   width;
    FT_Byte   height;
    FT_Char   left;
    FT_Char   top;

    FT_Byte   format;
    FT_Byte   max_grays;
    FT_Short  pitch;
    FT_Char   xadvance;
    FT_Char   yadvance;

    FT_Byte*  buffer;

  } FTC_SBitRec;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FTC_SBitCache                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a small bitmap cache.  These are special cache objects */
  /*    used to store small glyph bitmaps (and anti-aliased pixmaps) in a  */
  /*    much more efficient way than the traditional glyph image cache     */
  /*    implemented by @FTC_ImageCache.                                    */
  /*                                                                       */
  typedef struct FTC_SBitCacheRec_*  FTC_SBitCache;


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_SBitCache_New                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Creates a new cache to store small glyph bitmaps.                  */
  /*                                                                       */
  /* <Input>                                                               */
  /*    manager :: A handle to the source cache manager.                   */
  /*                                                                       */
  /* <Output>                                                              */
  /*    acache  :: A handle to the new sbit cache.  NULL in case of error. */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_SBitCache_New( FTC_Manager     manager,
                     FTC_SBitCache  *acache );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FTC_SBitCache_Lookup                                               */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Looks up a given small glyph bitmap in a given sbit cache and      */
  /*    `lock' it to prevent its flushing from the cache until needed.     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    cache  :: A handle to the source sbit cache.                       */
  /*                                                                       */
  /*    type   :: A pointer to the glyph image type descriptor.            */
  /*                                                                       */
  /*    gindex :: The glyph index.                                         */
  /*                                                                       */
  /* <Output>                                                              */
  /*    sbit   :: A handle to a small bitmap descriptor.                   */
  /*                                                                       */
  /*    anode  :: Used to return the address of of the corresponding cache */
  /*              node after incrementing its reference count (see note    */
  /*              below).                                                  */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The small bitmap descriptor and its bit buffer are owned by the    */
  /*    cache and should never be freed by the application.  They might    */
  /*    as well disappear from memory on the next cache lookup, so don't   */
  /*    treat them as persistent data.                                     */
  /*                                                                       */
  /*    The descriptor's `buffer' field is set to 0 to indicate a missing  */
  /*    glyph bitmap.                                                      */
  /*                                                                       */
  /*    If `anode' is _not_ NULL, it receives the address of the cache     */
  /*    node containing the bitmap, after increasing its reference count.  */
  /*    This ensures that the node (as well as the image) will always be   */
  /*    kept in the cache until you call @FTC_Node_Unref to `release' it.  */
  /*                                                                       */
  /*    If `anode' is NULL, the cache node is left unchanged, which means  */
  /*    that the bitmap could be flushed out of the cache on the next      */
  /*    call to one of the caching sub-system APIs.  Don't assume that it  */
  /*    is persistent!                                                     */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FTC_SBitCache_Lookup( FTC_SBitCache    cache,
                        FTC_ImageType    type,
                        FT_UInt          gindex,
                        FTC_SBit        *sbit,
                        FTC_Node        *anode );


 /* */

#ifdef FT_CONFIG_OPTION_OLD_INTERNALS

  /*@***********************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FTC_FontRec                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A simple structure used to describe a given `font' to the cache    */
  /*    manager.  Note that a `font' is the combination of a given face    */
  /*    with a given character size.                                       */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    face_id    :: The ID of the face to use.                           */
  /*                                                                       */
  /*    pix_width  :: The character width in integer pixels.               */
  /*                                                                       */
  /*    pix_height :: The character height in integer pixels.              */
  /*                                                                       */
  typedef struct  FTC_FontRec_
  {
    FTC_FaceID  face_id;
    FT_UShort   pix_width;
    FT_UShort   pix_height;

  } FTC_FontRec;


  /* */


#define FTC_FONT_COMPARE( f1, f2 )                  \
          ( (f1)->face_id    == (f2)->face_id    && \
            (f1)->pix_width  == (f2)->pix_width  && \
            (f1)->pix_height == (f2)->pix_height )

#define FTC_FONT_HASH( f )                              \
          (FT_UInt32)( FTC_FACE_ID_HASH((f)->face_id) ^ \
                       ((f)->pix_width << 8)          ^ \
                       ((f)->pix_height)              )

  typedef FTC_FontRec*  FTC_Font;


  FT_EXPORT( FT_Error )
  FTC_Manager_Lookup_Face( FTC_Manager  manager,
                           FTC_FaceID   face_id,
                           FT_Face     *aface );

  FT_EXPORT( FT_Error )
  FTC_Manager_Lookup_Size( FTC_Manager  manager,
                           FTC_Font     font,
                           FT_Face     *aface,
                           FT_Size     *asize );

#endif /* FT_CONFIG_OPTION_OLD_INTERNALS */


 /* */

FT_END_HEADER

#endif /* __FTCACHE_H__ */


/* END */