* include/freetype/ftincrem.h: adding new experimental header file
to demonstrate a "cleaner" API to support incremental font loading.
comments appreciated...
This commit is contained in:
David Turner
parent
b3d5e9cf03
commit
76effc302f
@ -1,3 +1,9 @@
|
||||
2002-07-30 David Turner <david@freetype.org>
|
||||
|
||||
* include/freetype/ftincrem.h: adding new experimental header file
|
||||
to demonstrate a "cleaner" API to support incremental font loading.
|
||||
comments appreciated...
|
||||
|
||||
2002-07-28 Werner Lemberg <wl@gnu.org>
|
||||
|
||||
s/ft_memset/FT_MEM_SET/.
|
||||
|
||||
203
include/freetype/ftincrem.h
Normal file
203
include/freetype/ftincrem.h
Normal file
@ -0,0 +1,203 @@
|
||||
#ifndef __FT_INCREMENTAL_H__
|
||||
#define __FT_INCREMENTAL_H__
|
||||
|
||||
#include <ft2build.h>
|
||||
#include FT_FREETYPE_H
|
||||
|
||||
FT_BEGIN_HEADER
|
||||
|
||||
/*************************************************************************
|
||||
*
|
||||
* @type: FT_Incremental
|
||||
*
|
||||
* @description:
|
||||
* an opaque type describing a user-provided object used to implement
|
||||
* "incremental" glyph loading within FreeType. This is used to support
|
||||
* embedded fonts in certain environments (e.g. Postscript interpreters),
|
||||
* where the glyph data isn't in the font file, or must be over-ridden by
|
||||
* different values.
|
||||
*
|
||||
* @note:
|
||||
* it's up to client applications to create and implement @FT_Incremental
|
||||
* objects, as long as they provide implementations for the methods
|
||||
* @FT_Incremental_GetGlyphDataFunc, @FT_Incremental_FreeGlyphDataFunc
|
||||
* and @FT_Incremental_GetGlyphMetricsFunc
|
||||
*
|
||||
* see the description of @FT_Incremental_ServiceRec to understand how to
|
||||
* use incremental objects with FreeType.
|
||||
*/
|
||||
typedef struct FT_IncrementalRec_* FT_Incremental;
|
||||
|
||||
|
||||
/*************************************************************************
|
||||
*
|
||||
* @struct: FT_Incremental_Metrics
|
||||
*
|
||||
* @description:
|
||||
* a small structure used to model the basic glyph metrics returned
|
||||
* by the @FT_Incremental_GetGlyphMetricsFunc method
|
||||
*
|
||||
* @fields:
|
||||
* bearing_x :: left-most bearing, in font units.
|
||||
* bearing_y :: top-most bearing, in font units.
|
||||
* advance :: glyph advance, in font units
|
||||
*
|
||||
* @note:
|
||||
* these correspond to horizontal or vertical metrics depending on the
|
||||
* value of the 'vertical' parameter of the method
|
||||
* @FT_Incremental_GetGlyphMetricsFunc
|
||||
*/
|
||||
typedef struct FT_Incremental_MetricsRec_
|
||||
{
|
||||
FT_Long bearing_x;
|
||||
FT_Long bearing_y;
|
||||
FT_Long advance;
|
||||
|
||||
} FT_Incremental_MetricsRec, *FT_Incremental_Metrics;
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @type: FT_Incremental_GetGlyphDataFunc
|
||||
*
|
||||
* @description:
|
||||
* a function called by FreeType to access a given glyph's data bytes
|
||||
* during @FT_Load_Glyph or @FT_Load_Char, when incremental loading is
|
||||
* enable.
|
||||
*
|
||||
* note that the format of the glyph's data bytes depends on the font
|
||||
* file format. For TrueType, it must correspond to the raw bytes within
|
||||
* the 'glyf' table. For Postscript formats, it must correspond to the
|
||||
* *unencrypted* charstrings bytes, without any 'lenIV' header. It is
|
||||
* undefined for any other format.
|
||||
*
|
||||
* @input:
|
||||
* incremental :: handle to an opaque @FT_Incremental handle provided
|
||||
* by the client application
|
||||
*
|
||||
* glyph_index :: index of relevant glyph
|
||||
*
|
||||
* @output:
|
||||
* adata :: a structure describing the returned glyph data bytes
|
||||
* (which will be accessed as a read-only byte block)
|
||||
*
|
||||
* @return:
|
||||
* FreeType error code. 0 means success
|
||||
*
|
||||
* @note:
|
||||
* if this function returns succesfully, the method
|
||||
* @FT_Incremental_FreeGlyphDataFunc will be called later to "release"
|
||||
* the se bytes.
|
||||
*
|
||||
* nested @FT_Incremental_GetGlyphDataFunc can happen, in the case of
|
||||
* compound glyphs !!
|
||||
*/
|
||||
typedef FT_Error (*FT_Incremental_GetGlyphDataFunc)
|
||||
( FT_Incremental incremental,
|
||||
FT_UInt glyph_index,
|
||||
FT_DataRec *adata );
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @type: FT_Incremental_FreeGlyphDataFunc
|
||||
*
|
||||
* @description:
|
||||
* a function used to "release" the glyph data bytes returned by a
|
||||
* successful call to @FT_Incremental_GetGlyphDataFunc.
|
||||
*
|
||||
* @input:
|
||||
* incremental :: handle to an opaque @FT_Incremental handle provided
|
||||
* by the client application
|
||||
*
|
||||
* data :: glyph_index :: index of relevant glyph
|
||||
*/
|
||||
typedef void (*FT_Incremental_FreeGlyphDataFunc)
|
||||
( FT_Incremental incremental,
|
||||
FT_DataRec* data );
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @type: FT_Incremental_GetGlyphMetricsFunc
|
||||
*
|
||||
* @description:
|
||||
* a function used to retrieve the basic metrics of a given glyph index
|
||||
* before accessing its data. This is necessary because, in certain formats
|
||||
* like TrueType, the metrics are stored in a different place than the
|
||||
* glyph images proper.
|
||||
*
|
||||
* @input:
|
||||
* incremental :: handle to an opaque @FT_Incremental handle provided
|
||||
* by the client application
|
||||
*
|
||||
*/
|
||||
typedef FT_Error (*FT_Incremental_GetGlyphMetricsFunc)
|
||||
( FT_Incremental incremental,
|
||||
FT_UInt glyph_index,
|
||||
FT_Bool vertical,
|
||||
FT_Incremental_MetricsRec *ametrics,
|
||||
FT_Bool *afound );
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @struct: FT_Incremental_ServiceRec
|
||||
*
|
||||
* @description:
|
||||
* a structure to be used with @FT_Open_Face to indicate that the user
|
||||
* wants to support "incremental" glyph loading. You should use it with
|
||||
* @FT_PARAM_TAG_INCREMENTAL as in the following example:
|
||||
*
|
||||
* {
|
||||
* FT_Incremental_ServiceRec incr_service;
|
||||
* FT_Parameter parameter;
|
||||
* FT_Open_Args open_args;
|
||||
*
|
||||
* // set up incremental descriptor
|
||||
* incr_service.incremental = my_object;
|
||||
* incr_service.get_glyph_metrics = my_get_glyph_metrics;
|
||||
* incr_service.get_glyph_data = my_get_glyph_data;
|
||||
* incr_service.free_glyph_data = my_free_glyph_data;
|
||||
*
|
||||
* // set up optional parameter
|
||||
* parameter.tag = FT_PARAM_TAG_INCREMENTAL;
|
||||
* parameter.data = &incr_service;
|
||||
*
|
||||
* // set up FT_Open_Args structure
|
||||
* open_args.flags = ft_open_flag_pathname;
|
||||
* open_args.pathname = my_font_pathname;
|
||||
* open_args.num_params = 1;
|
||||
* open_args.params = ¶meter; // we use one optional argument
|
||||
*
|
||||
* // open the
|
||||
* error = FT_Open_Face( library, &open_args, index, &face );
|
||||
* ....
|
||||
* }
|
||||
*/
|
||||
typedef struct FT_IncrementalParamsRec_
|
||||
{
|
||||
FT_Incremental incremental;
|
||||
FT_Incremental_GetGlyphMetricsFunc get_glyph_metrics;
|
||||
FT_Incremental_GetGlyphDataFunc get_glyph_data;
|
||||
FT_Incremental_FreeGlyphDataFunc free_glyph_data;
|
||||
|
||||
} FT_IncrementalParamsRec, *FT_IncrementalParams;
|
||||
|
||||
|
||||
/**************************************************************************
|
||||
*
|
||||
* @constant: FT_PARAM_TAG_INCREMENTAL
|
||||
*
|
||||
* @description:
|
||||
* a constant used as the tag of @FT_Parameter structures to indicate
|
||||
* an incremental loading object to be used by FreeType
|
||||
*
|
||||
* see the node for @FT_IncrementalParamsRec
|
||||
*/
|
||||
#define FT_PARAM_TAG_INCREMENTAL FT_MAKE_TAG('i','n','c','r')
|
||||
|
||||
/* */
|
||||
|
||||
FT_END_HEADER
|
||||
|
||||
#endif /* __FT_INCREMENTAL_H__ */
|
||||
Loading…
Reference in New Issue
Block a user