| /**************************************************************************** |
| * |
| * ftcache.h |
| * |
| * FreeType Cache subsystem (specification). |
| * |
| * Copyright (C) 1996-2020 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 */ |
