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Code Issues 4 Releases Wiki Activity

* include/freetype/ftcache.h: Formatted and updated.

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Alexei Podtelezhnikov 2023-05-11 23:23:52 -04:00
parent 7132f5b0d1
commit b07ab47b2a
1 changed files with 36 additions and 35 deletions
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include/freetype/ftcache.h
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@ -43,60 +43,61 @@ FT_BEGIN_HEADER
* 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.
* Note that all types and functions begin with the `FTC_` prefix rather
* than the usual `FT_` prefix int the rest of FreeType.
*
* 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:
* The cache is highly portable and, thus, doesn't know anything about
* the fonts installed on your system, or how to access them. Therefore,
* it requires the following:
*
* 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.
* * @FTC_FaceID, an arbitrary non-zero value, that uniquely identifies
* available or installed font faces, has to be 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 but they
* have to be persistent on the client side.
*
* 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.
* * @FTC_Face_Requester, a method to convert an @FTC_FaceID into a new
* @FT_Face object, when necessary, has to be provided to the cache by
* the client. The @FT_Face object is 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.
* Clients are free to map face IDs to anything useful. The most simple
* usage is, for example, to associate them to a {pathname,face_index}
* pair that is then used by @FTC_Face_Requester 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.
* crashes in @FTC_Face_Requester.
*
* 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.
* @FTC_Manager_LookupFace and @FTC_Manager_LookupSize, respectively, and
* use them in any FreeType work stream. You can also cache other
* FreeType objects as follows:
*
* 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 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_New,
* then later use @FTC_ImageCache_Lookup to retrieve the corresponding
* @FT_Glyph objects from the cache.
* * If you want to use the @FT_Glyph caching, call @FTC_ImageCache_New,
* 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.
* * 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).
*
*
* @order: