Edit File: ftcache.h
/***************************************************************************/ /* */ /* ftcache.h */ /* */ /* FreeType Cache subsystem (specification). */ /* */ /* Copyright 1996-2018 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 ); /************************************************************************* * * @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 ); /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /***** *****/ /***** 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 */
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