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Rev	Author	Line No.	Line
4680	right-hear	1	/***************************************************************************/
		2	/* */
		3	/* autohint.h */
		4	/* */
		5	/* High-level `autohint' module-specific interface (specification). */
		6	/* */
		7	/* Copyright 1996-2001, 2002, 2007 by */
		8	/* David Turner, Robert Wilhelm, and Werner Lemberg. */
		9	/* */
		10	/* This file is part of the FreeType project, and may only be used, */
		11	/* modified, and distributed under the terms of the FreeType project */
		12	/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
		13	/* this file you indicate that you have read the license and */
		14	/* understand and accept it fully. */
		15	/* */
		16	/***************************************************************************/
		17
		18
		19	/*************************************************************************/
		20	/* */
		21	/* The auto-hinter is used to load and automatically hint glyphs if a */
		22	/* format-specific hinter isn't available. */
		23	/* */
		24	/*************************************************************************/
		25
		26
		27	#ifndef __AUTOHINT_H__
		28	#define __AUTOHINT_H__
		29
		30
		31	/*************************************************************************/
		32	/* */
		33	/* A small technical note regarding automatic hinting in order to */
		34	/* clarify this module interface. */
		35	/* */
		36	/* An automatic hinter might compute two kinds of data for a given face: */
		37	/* */
		38	/* - global hints: Usually some metrics that describe global properties */
		39	/* of the face. It is computed by scanning more or less */
		40	/* aggressively the glyphs in the face, and thus can be */
		41	/* very slow to compute (even if the size of global */
		42	/* hints is really small). */
		43	/* */
		44	/* - glyph hints: These describe some important features of the glyph */
		45	/* outline, as well as how to align them. They are */
		46	/* generally much faster to compute than global hints. */
		47	/* */
		48	/* The current FreeType auto-hinter does a pretty good job while */
		49	/* performing fast computations for both global and glyph hints. */
		50	/* However, we might be interested in introducing more complex and */
		51	/* powerful algorithms in the future, like the one described in the John */
		52	/* D. Hobby paper, which unfortunately requires a lot more horsepower. */
		53	/* */
		54	/* Because a sufficiently sophisticated font management system would */
		55	/* typically implement an LRU cache of opened face objects to reduce */
		56	/* memory usage, it is a good idea to be able to avoid recomputing */
		57	/* global hints every time the same face is re-opened. */
		58	/* */
		59	/* We thus provide the ability to cache global hints outside of the face */
		60	/* object, in order to speed up font re-opening time. Of course, this */
		61	/* feature is purely optional, so most client programs won't even notice */
		62	/* it. */
		63	/* */
		64	/* I initially thought that it would be a good idea to cache the glyph */
		65	/* hints too. However, my general idea now is that if you really need */
		66	/* to cache these too, you are simply in need of a new font format, */
		67	/* where all this information could be stored within the font file and */
		68	/* decoded on the fly. */
		69	/* */
		70	/*************************************************************************/
		71
		72
		73	#include
		74	#include FT_FREETYPE_H
		75
		76
		77	FT_BEGIN_HEADER
		78
		79
		80	typedef struct FT_AutoHinterRec_ *FT_AutoHinter;
		81
		82
		83	/*************************************************************************/
		84	/* */
		85	/* */
		86	/* FT_AutoHinter_GlobalGetFunc */
		87	/* */
		88	/* */
		89	/* Retrieves the global hints computed for a given face object the */
		90	/* resulting data is dissociated from the face and will survive a */
		91	/* call to FT_Done_Face(). It must be discarded through the API */
		92	/* FT_AutoHinter_GlobalDoneFunc(). */
		93	/* */
		94	/* */
		95	/* hinter :: A handle to the source auto-hinter. */
		96	/* */
		97	/* face :: A handle to the source face object. */
		98	/* */
		99	/* */
		100	/* global_hints :: A typeless pointer to the global hints. */
		101	/* */
		102	/* global_len :: The size in bytes of the global hints. */
		103	/* */
		104	typedef void
		105	(*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter hinter,
		106	FT_Face face,
		107	void** global_hints,
		108	long* global_len );
		109
		110
		111	/*************************************************************************/
		112	/* */
		113	/* */
		114	/* FT_AutoHinter_GlobalDoneFunc */
		115	/* */
		116	/* */
		117	/* Discards the global hints retrieved through */
		118	/* FT_AutoHinter_GlobalGetFunc(). This is the only way these hints */
		119	/* are freed from memory. */
		120	/* */
		121	/* */
		122	/* hinter :: A handle to the auto-hinter module. */
		123	/* */
		124	/* global :: A pointer to retrieved global hints to discard. */
		125	/* */
		126	typedef void
		127	(*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter hinter,
		128	void* global );
		129
		130
		131	/*************************************************************************/
		132	/* */
		133	/* */
		134	/* FT_AutoHinter_GlobalResetFunc */
		135	/* */
		136	/* */
		137	/* This function is used to recompute the global metrics in a given */
		138	/* font. This is useful when global font data changes (e.g. Multiple */
		139	/* Masters fonts where blend coordinates change). */
		140	/* */
		141	/* */
		142	/* hinter :: A handle to the source auto-hinter. */
		143	/* */
		144	/* face :: A handle to the face. */
		145	/* */
		146	typedef void
		147	(*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter hinter,
		148	FT_Face face );
		149
		150
		151	/*************************************************************************/
		152	/* */
		153	/* */
		154	/* FT_AutoHinter_GlyphLoadFunc */
		155	/* */
		156	/* */
		157	/* This function is used to load, scale, and automatically hint a */
		158	/* glyph from a given face. */
		159	/* */
		160	/* */
		161	/* face :: A handle to the face. */
		162	/* */
		163	/* glyph_index :: The glyph index. */
		164	/* */
		165	/* load_flags :: The load flags. */
		166	/* */
		167	/* */
		168	/* This function is capable of loading composite glyphs by hinting */
		169	/* each sub-glyph independently (which improves quality). */
		170	/* */
		171	/* It will call the font driver with FT_Load_Glyph(), with */
		172	/* FT_LOAD_NO_SCALE set. */
		173	/* */
		174	typedef FT_Error
		175	(*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter hinter,
		176	FT_GlyphSlot slot,
		177	FT_Size size,
		178	FT_UInt glyph_index,
		179	FT_Int32 load_flags );
		180
		181
		182	/*************************************************************************/
		183	/* */
		184	/* */
		185	/* FT_AutoHinter_ServiceRec */
		186	/* */
		187	/* */
		188	/* The auto-hinter module's interface. */
		189	/* */
		190	typedef struct FT_AutoHinter_ServiceRec_
		191	{
		192	FT_AutoHinter_GlobalResetFunc reset_face;
		193	FT_AutoHinter_GlobalGetFunc get_global_hints;
		194	FT_AutoHinter_GlobalDoneFunc done_global_hints;
		195	FT_AutoHinter_GlyphLoadFunc load_glyph;
		196
		197	} FT_AutoHinter_ServiceRec, *FT_AutoHinter_Service;
		198
		199	#ifndef FT_CONFIG_OPTION_PIC
		200
		201	#define FT_DEFINE_AUTOHINTER_SERVICE(class_, reset_face_, get_global_hints_, \
		202	done_global_hints_, load_glyph_) \
		203	FT_CALLBACK_TABLE_DEF \
		204	const FT_AutoHinter_ServiceRec class_ = \
		205	{ \
		206	reset_face_, get_global_hints_, done_global_hints_, load_glyph_ \
		207	};
		208
		209	#else /* FT_CONFIG_OPTION_PIC */
		210
		211	#define FT_DEFINE_AUTOHINTER_SERVICE(class_, reset_face_, get_global_hints_, \
		212	done_global_hints_, load_glyph_) \
		213	void \
		214	FT_Init_Class_##class_( FT_Library library, \
		215	FT_AutoHinter_ServiceRec* clazz) \
		216	{ \
		217	FT_UNUSED(library); \
		218	clazz->reset_face = reset_face_; \
		219	clazz->get_global_hints = get_global_hints_; \
		220	clazz->done_global_hints = done_global_hints_; \
		221	clazz->load_glyph = load_glyph_; \
		222	}
		223
		224	#endif /* FT_CONFIG_OPTION_PIC */
		225
		226	FT_END_HEADER
		227
		228	#endif /* __AUTOHINT_H__ */
		229
		230
		231	/* END */

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