1089 lines
33 KiB
C
1089 lines
33 KiB
C
/****************************************************************************
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*
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* ftcache.h
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*
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* FreeType Cache subsystem (specification).
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*
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* Copyright (C) 1996-2020 by
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* David Turner, Robert Wilhelm, and Werner Lemberg.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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#ifndef FTCACHE_H_
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#define FTCACHE_H_
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#include <ft2build.h>
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#include FT_GLYPH_H
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FT_BEGIN_HEADER
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/**************************************************************************
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*
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* @section:
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* cache_subsystem
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*
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* @title:
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* Cache Sub-System
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*
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* @abstract:
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* How to cache face, size, and glyph data with FreeType~2.
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*
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* @description:
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* This section describes the FreeType~2 cache sub-system, which is used
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* to limit the number of concurrently opened @FT_Face and @FT_Size
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* objects, as well as caching information like character maps and glyph
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* images while limiting their maximum memory usage.
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*
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* Note that all types and functions begin with the `FTC_` prefix.
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*
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* The cache is highly portable and thus doesn't know anything about the
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* fonts installed on your system, or how to access them. This implies
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* the following scheme:
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*
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* First, available or installed font faces are uniquely identified by
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* @FTC_FaceID values, provided to the cache by the client. Note that
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* the cache only stores and compares these values, and doesn't try to
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* interpret them in any way.
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*
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* Second, the cache calls, only when needed, a client-provided function
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* to convert an @FTC_FaceID into a new @FT_Face object. The latter is
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* then completely managed by the cache, including its termination
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* through @FT_Done_Face. To monitor termination of face objects, the
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* finalizer callback in the `generic` field of the @FT_Face object can
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* be used, which might also be used to store the @FTC_FaceID of the
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* face.
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*
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* Clients are free to map face IDs to anything else. The most simple
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* usage is to associate them to a (pathname,face_index) pair that is
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* used to call @FT_New_Face. However, more complex schemes are also
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* possible.
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*
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* Note that for the cache to work correctly, the face ID values must be
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* **persistent**, which means that the contents they point to should not
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* change at runtime, or that their value should not become invalid.
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*
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* If this is unavoidable (e.g., when a font is uninstalled at runtime),
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* you should call @FTC_Manager_RemoveFaceID as soon as possible, to let
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* the cache get rid of any references to the old @FTC_FaceID it may keep
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* internally. Failure to do so will lead to incorrect behaviour or even
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* crashes.
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*
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* To use the cache, start with calling @FTC_Manager_New to create a new
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* @FTC_Manager object, which models a single cache instance. You can
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* then look up @FT_Face and @FT_Size objects with
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* @FTC_Manager_LookupFace and @FTC_Manager_LookupSize, respectively.
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*
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* If you want to use the charmap caching, call @FTC_CMapCache_New, then
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* later use @FTC_CMapCache_Lookup to perform the equivalent of
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* @FT_Get_Char_Index, only much faster.
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*
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* If you want to use the @FT_Glyph caching, call @FTC_ImageCache, then
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* later use @FTC_ImageCache_Lookup to retrieve the corresponding
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* @FT_Glyph objects from the cache.
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*
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* If you need lots of small bitmaps, it is much more memory efficient to
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* call @FTC_SBitCache_New followed by @FTC_SBitCache_Lookup. This
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* returns @FTC_SBitRec structures, which are used to store small bitmaps
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* directly. (A small bitmap is one whose metrics and dimensions all fit
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* into 8-bit integers).
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*
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* We hope to also provide a kerning cache in the near future.
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*
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*
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* @order:
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* FTC_Manager
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* FTC_FaceID
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* FTC_Face_Requester
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*
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* FTC_Manager_New
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* FTC_Manager_Reset
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* FTC_Manager_Done
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* FTC_Manager_LookupFace
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* FTC_Manager_LookupSize
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* FTC_Manager_RemoveFaceID
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*
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* FTC_Node
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* FTC_Node_Unref
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*
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* FTC_ImageCache
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* FTC_ImageCache_New
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* FTC_ImageCache_Lookup
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*
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* FTC_SBit
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* FTC_SBitCache
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* FTC_SBitCache_New
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* FTC_SBitCache_Lookup
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*
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* FTC_CMapCache
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* FTC_CMapCache_New
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* FTC_CMapCache_Lookup
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*
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*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** BASIC TYPE DEFINITIONS *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/**************************************************************************
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*
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* @type:
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* FTC_FaceID
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*
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* @description:
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* An opaque pointer type that is used to identity face objects. The
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* contents of such objects is application-dependent.
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*
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* These pointers are typically used to point to a user-defined structure
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* containing a font file path, and face index.
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*
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* @note:
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* Never use `NULL` as a valid @FTC_FaceID.
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*
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* Face IDs are passed by the client to the cache manager that calls,
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* when needed, the @FTC_Face_Requester to translate them into new
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* @FT_Face objects.
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*
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* If the content of a given face ID changes at runtime, or if the value
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* becomes invalid (e.g., when uninstalling a font), you should
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* immediately call @FTC_Manager_RemoveFaceID before any other cache
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* function.
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*
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* Failure to do so will result in incorrect behaviour or even memory
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* leaks and crashes.
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*/
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typedef FT_Pointer FTC_FaceID;
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/**************************************************************************
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*
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* @functype:
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* FTC_Face_Requester
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*
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* @description:
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* A callback function provided by client applications. It is used by
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* the cache manager to translate a given @FTC_FaceID into a new valid
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* @FT_Face object, on demand.
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*
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* @input:
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* face_id ::
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* The face ID to resolve.
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*
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* library ::
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* A handle to a FreeType library object.
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*
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* req_data ::
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* Application-provided request data (see note below).
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*
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* @output:
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* aface ::
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* A new @FT_Face handle.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* The third parameter `req_data` is the same as the one passed by the
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* client when @FTC_Manager_New is called.
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*
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* The face requester should not perform funny things on the returned
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* face object, like creating a new @FT_Size for it, or setting a
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* transformation through @FT_Set_Transform!
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*/
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typedef FT_Error
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(*FTC_Face_Requester)( FTC_FaceID face_id,
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FT_Library library,
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FT_Pointer req_data,
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FT_Face* aface );
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/* */
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/***** *****/
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/***** CACHE MANAGER OBJECT *****/
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/***** *****/
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/*************************************************************************/
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/*************************************************************************/
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/*************************************************************************/
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/**************************************************************************
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*
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* @type:
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* FTC_Manager
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*
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* @description:
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* This object corresponds to one instance of the cache-subsystem. It is
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* used to cache one or more @FT_Face objects, along with corresponding
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* @FT_Size objects.
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*
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* The manager intentionally limits the total number of opened @FT_Face
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* and @FT_Size objects to control memory usage. See the `max_faces` and
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* `max_sizes` parameters of @FTC_Manager_New.
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*
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* The manager is also used to cache 'nodes' of various types while
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* limiting their total memory usage.
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*
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* All limitations are enforced by keeping lists of managed objects in
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* most-recently-used order, and flushing old nodes to make room for new
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* ones.
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*/
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typedef struct FTC_ManagerRec_* FTC_Manager;
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/**************************************************************************
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*
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* @type:
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* FTC_Node
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*
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* @description:
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* An opaque handle to a cache node object. Each cache node is
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* reference-counted. A node with a count of~0 might be flushed out of a
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* full cache whenever a lookup request is performed.
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*
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* If you look up nodes, you have the ability to 'acquire' them, i.e., to
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* increment their reference count. This will prevent the node from
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* being flushed out of the cache until you explicitly 'release' it (see
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* @FTC_Node_Unref).
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*
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* See also @FTC_SBitCache_Lookup and @FTC_ImageCache_Lookup.
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*/
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typedef struct FTC_NodeRec_* FTC_Node;
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/**************************************************************************
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*
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* @function:
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* FTC_Manager_New
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*
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* @description:
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* Create a new cache manager.
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*
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* @input:
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* library ::
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* The parent FreeType library handle to use.
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*
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* max_faces ::
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* Maximum number of opened @FT_Face objects managed by this cache
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* instance. Use~0 for defaults.
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*
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* max_sizes ::
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* Maximum number of opened @FT_Size objects managed by this cache
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* instance. Use~0 for defaults.
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*
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* max_bytes ::
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* Maximum number of bytes to use for cached data nodes. Use~0 for
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* defaults. Note that this value does not account for managed
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* @FT_Face and @FT_Size objects.
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*
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* requester ::
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* An application-provided callback used to translate face IDs into
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* real @FT_Face objects.
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*
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* req_data ::
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* A generic pointer that is passed to the requester each time it is
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* called (see @FTC_Face_Requester).
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*
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* @output:
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* amanager ::
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* A handle to a new manager object. 0~in case of failure.
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*
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* @return:
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* FreeType error code. 0~means success.
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*/
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FT_EXPORT( FT_Error )
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FTC_Manager_New( FT_Library library,
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FT_UInt max_faces,
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FT_UInt max_sizes,
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FT_ULong max_bytes,
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FTC_Face_Requester requester,
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FT_Pointer req_data,
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FTC_Manager *amanager );
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/**************************************************************************
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*
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* @function:
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* FTC_Manager_Reset
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*
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* @description:
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* Empty a given cache manager. This simply gets rid of all the
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* currently cached @FT_Face and @FT_Size objects within the manager.
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*
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* @inout:
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* manager ::
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* A handle to the manager.
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*/
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FT_EXPORT( void )
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FTC_Manager_Reset( FTC_Manager manager );
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/**************************************************************************
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*
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* @function:
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* FTC_Manager_Done
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*
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* @description:
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* Destroy a given manager after emptying it.
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*
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* @input:
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* manager ::
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* A handle to the target cache manager object.
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*/
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FT_EXPORT( void )
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FTC_Manager_Done( FTC_Manager manager );
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/**************************************************************************
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*
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* @function:
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* FTC_Manager_LookupFace
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*
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* @description:
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* Retrieve the @FT_Face object that corresponds to a given face ID
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* through a cache manager.
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*
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* @input:
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* manager ::
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* A handle to the cache manager.
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*
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* face_id ::
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* The ID of the face object.
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*
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* @output:
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* aface ::
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* A handle to the face object.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* The returned @FT_Face object is always owned by the manager. You
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* should never try to discard it yourself.
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*
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* The @FT_Face object doesn't necessarily have a current size object
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* (i.e., face->size can be~0). If you need a specific 'font size', use
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* @FTC_Manager_LookupSize instead.
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*
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* Never change the face's transformation matrix (i.e., never call the
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* @FT_Set_Transform function) on a returned face! If you need to
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* transform glyphs, do it yourself after glyph loading.
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*
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* When you perform a lookup, out-of-memory errors are detected _within_
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* the lookup and force incremental flushes of the cache until enough
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* memory is released for the lookup to succeed.
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*
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* If a lookup fails with `FT_Err_Out_Of_Memory` the cache has already
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* been completely flushed, and still no memory was available for the
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* operation.
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*/
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FT_EXPORT( FT_Error )
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FTC_Manager_LookupFace( FTC_Manager manager,
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FTC_FaceID face_id,
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FT_Face *aface );
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/**************************************************************************
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*
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* @struct:
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* FTC_ScalerRec
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*
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* @description:
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* A structure used to describe a given character size in either pixels
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* or points to the cache manager. See @FTC_Manager_LookupSize.
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*
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* @fields:
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* face_id ::
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* The source face ID.
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*
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* width ::
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* The character width.
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*
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* height ::
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* The character height.
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*
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* pixel ::
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* A Boolean. If 1, the `width` and `height` fields are interpreted as
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* integer pixel character sizes. Otherwise, they are expressed as
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* 1/64th of points.
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*
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* x_res ::
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* Only used when `pixel` is value~0 to indicate the horizontal
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* resolution in dpi.
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*
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* y_res ::
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* Only used when `pixel` is value~0 to indicate the vertical
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* resolution in dpi.
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*
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* @note:
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* This type is mainly used to retrieve @FT_Size objects through the
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* cache manager.
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*/
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typedef struct FTC_ScalerRec_
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{
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FTC_FaceID face_id;
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FT_UInt width;
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FT_UInt height;
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FT_Int pixel;
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FT_UInt x_res;
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FT_UInt y_res;
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} FTC_ScalerRec;
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/**************************************************************************
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*
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* @struct:
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* FTC_Scaler
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*
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* @description:
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* A handle to an @FTC_ScalerRec structure.
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*/
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typedef struct FTC_ScalerRec_* FTC_Scaler;
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/**************************************************************************
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*
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* @function:
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* FTC_Manager_LookupSize
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*
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* @description:
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* Retrieve the @FT_Size object that corresponds to a given
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* @FTC_ScalerRec pointer through a cache manager.
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*
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* @input:
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* manager ::
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* A handle to the cache manager.
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*
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* scaler ::
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* A scaler handle.
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*
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* @output:
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* asize ::
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* A handle to the size object.
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*
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* @return:
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* FreeType error code. 0~means success.
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*
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* @note:
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* The returned @FT_Size object is always owned by the manager. You
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* should never try to discard it by yourself.
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*
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* You can access the parent @FT_Face object simply as `size->face` if
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* you need it. Note that this object is also owned by the manager.
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*
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|
* @note:
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* 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
|
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* been completely flushed, and still no memory is available for the
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* operation.
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*/
|
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FT_EXPORT( FT_Error )
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FTC_Manager_LookupSize( FTC_Manager manager,
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FTC_Scaler scaler,
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FT_Size *asize );
|
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|
|
|
|
/**************************************************************************
|
|
*
|
|
* @function:
|
|
* FTC_Node_Unref
|
|
*
|
|
* @description:
|
|
* Decrement a cache node's internal reference count. When the count
|
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* reaches 0, it is not destroyed but becomes eligible for subsequent
|
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* cache flushes.
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*
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* @input:
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* node ::
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* The cache node handle.
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*
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* manager ::
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* The cache manager handle.
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*/
|
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FT_EXPORT( void )
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FTC_Node_Unref( FTC_Node node,
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FTC_Manager manager );
|
|
|
|
|
|
/**************************************************************************
|
|
*
|
|
* @function:
|
|
* FTC_Manager_RemoveFaceID
|
|
*
|
|
* @description:
|
|
* A special function used to indicate to the cache manager that a given
|
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* @FTC_FaceID is no longer valid, either because its content changed, or
|
|
* because it was deallocated or uninstalled.
|
|
*
|
|
* @input:
|
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* manager ::
|
|
* The cache manager handle.
|
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*
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* face_id ::
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* The @FTC_FaceID to be removed.
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*
|
|
* @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.
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*
|
|
*/
|
|
FT_EXPORT( void )
|
|
FTC_Manager_RemoveFaceID( FTC_Manager manager,
|
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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 */
|