245 lines
14 KiB
C
245 lines
14 KiB
C
/***************************************************************************/
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/* */
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/* autohint.h */
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/* */
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/* High-level `autohint' module-specific interface (specification). */
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/* */
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/* Copyright 1996-2002, 2007, 2009, 2012 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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/*************************************************************************/
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/* */
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/* The auto-hinter is used to load and automatically hint glyphs if a */
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/* format-specific hinter isn't available. */
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/* */
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/*************************************************************************/
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#ifndef __AUTOHINT_H__
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#define __AUTOHINT_H__
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/*************************************************************************/
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/* */
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/* A small technical note regarding automatic hinting in order to */
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/* clarify this module interface. */
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/* */
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/* An automatic hinter might compute two kinds of data for a given face: */
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/* */
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/* - global hints: Usually some metrics that describe global properties */
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/* of the face. It is computed by scanning more or less */
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/* aggressively the glyphs in the face, and thus can be */
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/* very slow to compute (even if the size of global */
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/* hints is really small). */
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/* */
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/* - glyph hints: These describe some important features of the glyph */
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/* outline, as well as how to align them. They are */
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/* generally much faster to compute than global hints. */
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/* */
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/* The current FreeType auto-hinter does a pretty good job while */
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/* performing fast computations for both global and glyph hints. */
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/* However, we might be interested in introducing more complex and */
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/* powerful algorithms in the future, like the one described in the John */
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/* D. Hobby paper, which unfortunately requires a lot more horsepower. */
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/* */
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/* Because a sufficiently sophisticated font management system would */
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/* typically implement an LRU cache of opened face objects to reduce */
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/* memory usage, it is a good idea to be able to avoid recomputing */
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/* global hints every time the same face is re-opened. */
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/* */
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/* We thus provide the ability to cache global hints outside of the face */
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/* object, in order to speed up font re-opening time. Of course, this */
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/* feature is purely optional, so most client programs won't even notice */
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/* it. */
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/* */
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/* I initially thought that it would be a good idea to cache the glyph */
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/* hints too. However, my general idea now is that if you really need */
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/* to cache these too, you are simply in need of a new font format, */
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/* where all this information could be stored within the font file and */
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/* decoded on the fly. */
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/* */
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/*************************************************************************/
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#include <ft2build.h>
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#include FT_FREETYPE_H
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FT_BEGIN_HEADER
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typedef struct FT_AutoHinterRec_ *FT_AutoHinter;
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/*************************************************************************/
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/* */
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/* <FuncType> */
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/* FT_AutoHinter_GlobalGetFunc */
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/* */
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/* <Description> */
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/* Retrieve the global hints computed for a given face object. The */
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/* resulting data is dissociated from the face and will survive a */
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/* call to FT_Done_Face(). It must be discarded through the API */
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/* FT_AutoHinter_GlobalDoneFunc(). */
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/* */
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/* <Input> */
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/* hinter :: A handle to the source auto-hinter. */
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/* */
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/* face :: A handle to the source face object. */
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/* */
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/* <Output> */
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/* global_hints :: A typeless pointer to the global hints. */
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/* */
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/* global_len :: The size in bytes of the global hints. */
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/* */
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typedef void
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(*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter hinter,
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FT_Face face,
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void** global_hints,
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long* global_len );
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/*************************************************************************/
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/* */
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/* <FuncType> */
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/* FT_AutoHinter_GlobalDoneFunc */
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/* */
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/* <Description> */
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/* Discard the global hints retrieved through */
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/* FT_AutoHinter_GlobalGetFunc(). This is the only way these hints */
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/* are freed from memory. */
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/* */
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/* <Input> */
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/* hinter :: A handle to the auto-hinter module. */
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/* */
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/* global :: A pointer to retrieved global hints to discard. */
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/* */
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typedef void
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(*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter hinter,
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void* global );
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/*************************************************************************/
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/* */
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/* <FuncType> */
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/* FT_AutoHinter_GlobalResetFunc */
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/* */
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/* <Description> */
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/* This function is used to recompute the global metrics in a given */
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/* font. This is useful when global font data changes (e.g. Multiple */
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/* Masters fonts where blend coordinates change). */
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/* */
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/* <Input> */
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/* hinter :: A handle to the source auto-hinter. */
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/* */
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/* face :: A handle to the face. */
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/* */
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typedef void
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(*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter hinter,
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FT_Face face );
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/*************************************************************************/
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/* */
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/* <FuncType> */
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/* FT_AutoHinter_GlyphLoadFunc */
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/* */
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/* <Description> */
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/* This function is used to load, scale, and automatically hint a */
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/* glyph from a given face. */
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/* */
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/* <Input> */
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/* face :: A handle to the face. */
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/* */
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/* glyph_index :: The glyph index. */
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/* */
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/* load_flags :: The load flags. */
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/* */
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/* <Note> */
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/* This function is capable of loading composite glyphs by hinting */
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/* each sub-glyph independently (which improves quality). */
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/* */
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/* It will call the font driver with @FT_Load_Glyph, with */
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/* @FT_LOAD_NO_SCALE set. */
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/* */
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typedef FT_Error
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(*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter hinter,
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FT_GlyphSlot slot,
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FT_Size size,
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FT_UInt glyph_index,
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FT_Int32 load_flags );
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/*************************************************************************/
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/* */
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/* <Struct> */
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/* FT_AutoHinter_InterfaceRec */
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/* */
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/* <Description> */
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/* The auto-hinter module's interface. */
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/* */
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typedef struct FT_AutoHinter_InterfaceRec_
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{
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FT_AutoHinter_GlobalResetFunc reset_face;
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FT_AutoHinter_GlobalGetFunc get_global_hints;
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FT_AutoHinter_GlobalDoneFunc done_global_hints;
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FT_AutoHinter_GlyphLoadFunc load_glyph;
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} FT_AutoHinter_InterfaceRec, *FT_AutoHinter_Interface;
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#ifndef FT_CONFIG_OPTION_PIC
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#define FT_DEFINE_AUTOHINTER_INTERFACE( \
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class_, \
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reset_face_, \
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get_global_hints_, \
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done_global_hints_, \
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load_glyph_ ) \
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FT_CALLBACK_TABLE_DEF \
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const FT_AutoHinter_InterfaceRec class_ = \
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{ \
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reset_face_, \
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get_global_hints_, \
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done_global_hints_, \
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load_glyph_ \
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};
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#else /* FT_CONFIG_OPTION_PIC */
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#define FT_DEFINE_AUTOHINTER_INTERFACE( \
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class_, \
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reset_face_, \
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get_global_hints_, \
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done_global_hints_, \
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load_glyph_ ) \
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void \
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FT_Init_Class_ ## class_( FT_Library library, \
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FT_AutoHinter_InterfaceRec* clazz ) \
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{ \
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FT_UNUSED( library ); \
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\
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clazz->reset_face = reset_face_; \
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clazz->get_global_hints = get_global_hints_; \
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clazz->done_global_hints = done_global_hints_; \
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clazz->load_glyph = load_glyph_; \
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}
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#endif /* FT_CONFIG_OPTION_PIC */
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FT_END_HEADER
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#endif /* __AUTOHINT_H__ */
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/* END */
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