ref: 9428ee42c0100381a60c57544773ae58c4d1028c
dir: /include/freetype/ftcache.h/
/***************************************************************************/
/* */
/* ftcache.h */
/* */
/* FreeType Cache subsystem (specification). */
/* */
/* Copyright 1996-2017 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 or 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 calls, only when needed, a client-provided function
* to convert an @FTC_FaceID into a new @FT_Face object. The latter is
* then completely managed by the cache, including its termination
* through @FT_Done_Face. To monitor termination of face objects, the
* finalizer callback in the `generic' field of the @FT_Face object can
* be used, which might also be used to store the @FTC_FaceID of the
* face.
*
* Clients are free to map face IDs to anything else. 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 contents 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 with calling @FTC_Manager_New to create a new
* @FTC_Manager object, which models a single cache instance. You can
* then look up @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 followed by @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 into 8-bit integers).
*
* We hope to also provide a kerning cache in the near future.
*
*
* <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 that calls,
* 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 FT_Pointer 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 as 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 req_data,
FT_Face* aface );
/* */
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** 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 control 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 look up 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> */
/* Create 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. Use~0 for defaults. */
/* */
/* max_sizes :: Maximum number of opened @FT_Size objects managed by */
/* this cache instance. Use~0 for defaults. */
/* */
/* 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> */
/* Empty 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> */
/* Destroy 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> */
/* Retrieve 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. */
/* */
/* 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 was 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 1, 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 value~0 to indicate the */
/* horizontal resolution in dpi. */
/* */
/* y_res :: Only used when `pixel' is value~0 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;
/*************************************************************************/
/* */
/* <Struct> */
/* FTC_Scaler */
/* */
/* <Description> */
/* A handle to an @FTC_ScalerRec structure. */
/* */
typedef struct FTC_ScalerRec_* FTC_Scaler;
/*************************************************************************/
/* */
/* <Function> */
/* FTC_Manager_LookupSize */
/* */
/* <Description> */
/* Retrieve the @FT_Size object that corresponds to a given */
/* @FTC_ScalerRec pointer 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 );
/*************************************************************************
*
* @function:
* FTC_Manager_RemoveFaceID
*
* @description:
* A special function used to indicate to the cache manager that
* a given @FTC_FaceID is no longer valid, either because its
* content changed, or because it was deallocated or uninstalled.
*
* @input:
* manager ::
* The cache manager handle.
*
* face_id ::
* The @FTC_FaceID to be removed.
*
* @note:
* This function flushes all nodes from the cache corresponding to this
* `face_id', with the exception of nodes with a non-null reference
* count.
*
* Such nodes are however modified internally so as to never appear
* in later lookups with the same `face_id' value, and to be immediately
* destroyed when released by all their users.
*
*/
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 model 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. Any negative value
* means to use the cache @FT_Face's default charmap.
*
* 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 *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************
*
* @struct:
* FTC_ImageTypeRec
*
* @description:
* A structure used to model the type of images in a glyph cache.
*
* @fields:
* face_id ::
* The face ID.
*
* width ::
* The width in pixels.
*
* height ::
* The height in pixels.
*
* flags ::
* The load flags, as in @FT_Load_Glyph.
*
*/
typedef struct FTC_ImageTypeRec_
{
FTC_FaceID face_id;
FT_UInt width;
FT_UInt height;
FT_Int32 flags;
} FTC_ImageTypeRec;
/*************************************************************************
*
* @type:
* FTC_ImageType
*
* @description:
* A handle to an @FTC_ImageTypeRec structure.
*
*/
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 )
/*************************************************************************/
/* */
/* <Type> */
/* FTC_ImageCache */
/* */
/* <Description> */
/* A handle to a 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> */
/* Create 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> */
/* Retrieve 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 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 );
/*************************************************************************/
/* */
/* <Function> */
/* FTC_ImageCache_LookupScaler */
/* */
/* <Description> */
/* A variant of @FTC_ImageCache_Lookup that uses an @FTC_ScalerRec */
/* to specify the face ID and its size. */
/* */
/* <Input> */
/* cache :: A handle to the source glyph image cache. */
/* */
/* scaler :: A pointer to a scaler descriptor. */
/* */
/* load_flags :: The corresponding load flags. */
/* */
/* 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 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! */
/* */
/* Calls to @FT_Set_Char_Size and friends have no effect on cached */
/* glyphs; you should always use the FreeType cache API instead. */
/* */
FT_EXPORT( FT_Error )
FTC_ImageCache_LookupScaler( FTC_ImageCache cache,
FTC_Scaler scaler,
FT_ULong load_flags,
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> */
/* Create 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> */
/* Look 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 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 );
/*************************************************************************/
/* */
/* <Function> */
/* FTC_SBitCache_LookupScaler */
/* */
/* <Description> */
/* A variant of @FTC_SBitCache_Lookup that uses an @FTC_ScalerRec */
/* to specify the face ID and its size. */
/* */
/* <Input> */
/* cache :: A handle to the source sbit cache. */
/* */
/* scaler :: A pointer to the scaler descriptor. */
/* */
/* load_flags :: The corresponding load flags. */
/* */
/* gindex :: The glyph index. */
/* */
/* <Output> */
/* sbit :: A handle to a small bitmap descriptor. */
/* */
/* anode :: Used to return the address 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_LookupScaler( FTC_SBitCache cache,
FTC_Scaler scaler,
FT_ULong load_flags,
FT_UInt gindex,
FTC_SBit *sbit,
FTC_Node *anode );
/* */
FT_END_HEADER
#endif /* FTCACHE_H_ */
/* END */