[692] | 1 | /***************************************************************************/
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| 2 | /* */
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| 3 | /* autohint.h */
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| 4 | /* */
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| 5 | /* High-level `autohint' module-specific interface (specification). */
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| 6 | /* */
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| 7 | /* Copyright 1996-2001, 2002 by */
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| 8 | /* David Turner, Robert Wilhelm, and Werner Lemberg. */
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| 9 | /* */
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| 10 | /* This file is part of the FreeType project, and may only be used, */
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| 11 | /* modified, and distributed under the terms of the FreeType project */
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| 12 | /* license, LICENSE.TXT. By continuing to use, modify, or distribute */
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| 13 | /* this file you indicate that you have read the license and */
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| 14 | /* understand and accept it fully. */
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| 15 | /* */
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| 16 | /***************************************************************************/
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| 17 |
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| 18 |
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| 19 | /*************************************************************************/
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| 20 | /* */
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| 21 | /* The auto-hinter is used to load and automatically hint glyphs if a */
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| 22 | /* format-specific hinter isn't available. */
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| 23 | /* */
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| 24 | /*************************************************************************/
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| 25 |
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| 26 |
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| 27 | #ifndef __AUTOHINT_H__
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| 28 | #define __AUTOHINT_H__
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| 29 |
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| 30 |
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| 31 | /*************************************************************************/
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| 32 | /* */
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| 33 | /* A small technical note regarding automatic hinting in order to */
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| 34 | /* clarify this module interface. */
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| 35 | /* */
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| 36 | /* An automatic hinter might compute two kinds of data for a given face: */
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| 37 | /* */
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| 38 | /* - global hints: Usually some metrics that describe global properties */
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| 39 | /* of the face. It is computed by scanning more or less */
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| 40 | /* agressively the glyphs in the face, and thus can be */
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| 41 | /* very slow to compute (even if the size of global */
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| 42 | /* hints is really small). */
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| 43 | /* */
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| 44 | /* - glyph hints: These describe some important features of the glyph */
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| 45 | /* outline, as well as how to align them. They are */
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| 46 | /* generally much faster to compute than global hints. */
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| 47 | /* */
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| 48 | /* The current FreeType auto-hinter does a pretty good job while */
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| 49 | /* performing fast computations for both global and glyph hints. */
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| 50 | /* However, we might be interested in introducing more complex and */
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| 51 | /* powerful algorithms in the future, like the one described in the John */
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| 52 | /* D. Hobby paper, which unfortunately requires a lot more horsepower. */
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| 53 | /* */
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| 54 | /* Because a sufficiently sophisticated font management system would */
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| 55 | /* typically implement an LRU cache of opened face objects to reduce */
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| 56 | /* memory usage, it is a good idea to be able to avoid recomputing */
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| 57 | /* global hints every time the same face is re-opened. */
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| 58 | /* */
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| 59 | /* We thus provide the ability to cache global hints outside of the face */
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| 60 | /* object, in order to speed up font re-opening time. Of course, this */
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| 61 | /* feature is purely optional, so most client programs won't even notice */
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| 62 | /* it. */
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| 63 | /* */
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| 64 | /* I initially thought that it would be a good idea to cache the glyph */
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| 65 | /* hints too. However, my general idea now is that if you really need */
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| 66 | /* to cache these too, you are simply in need of a new font format, */
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| 67 | /* where all this information could be stored within the font file and */
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| 68 | /* decoded on the fly. */
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| 69 | /* */
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| 70 | /*************************************************************************/
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| 71 |
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| 72 |
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| 73 | #include <ft2build.h>
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| 74 | #include FT_FREETYPE_H
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| 75 |
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| 76 |
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| 77 | FT_BEGIN_HEADER
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| 78 |
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| 79 |
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| 80 | typedef struct FT_AutoHinterRec_ *FT_AutoHinter;
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| 81 |
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| 82 |
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| 83 | /*************************************************************************/
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| 84 | /* */
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| 85 | /* <FuncType> */
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| 86 | /* FT_AutoHinter_GlobalGetFunc */
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| 87 | /* */
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| 88 | /* <Description> */
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| 89 | /* Retrieves the global hints computed for a given face object the */
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| 90 | /* resulting data is dissociated from the face and will survive a */
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| 91 | /* call to FT_Done_Face(). It must be discarded through the API */
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| 92 | /* FT_AutoHinter_GlobalDoneFunc(). */
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| 93 | /* */
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| 94 | /* <Input> */
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| 95 | /* hinter :: A handle to the source auto-hinter. */
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| 96 | /* */
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| 97 | /* face :: A handle to the source face object. */
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| 98 | /* */
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| 99 | /* <Output> */
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| 100 | /* global_hints :: A typeless pointer to the global hints. */
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| 101 | /* */
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| 102 | /* global_len :: The size in bytes of the global hints. */
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| 103 | /* */
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| 104 | typedef void
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| 105 | (*FT_AutoHinter_GlobalGetFunc)( FT_AutoHinter hinter,
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| 106 | FT_Face face,
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| 107 | void** global_hints,
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| 108 | long* global_len );
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| 109 |
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| 110 |
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| 111 | /*************************************************************************/
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| 112 | /* */
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| 113 | /* <FuncType> */
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| 114 | /* FT_AutoHinter_GlobalDoneFunc */
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| 115 | /* */
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| 116 | /* <Description> */
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| 117 | /* Discards the global hints retrieved through */
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| 118 | /* FT_AutoHinter_GlobalGetFunc(). This is the only way these hints */
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| 119 | /* are freed from memory. */
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| 120 | /* */
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| 121 | /* <Input> */
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| 122 | /* hinter :: A handle to the auto-hinter module. */
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| 123 | /* */
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| 124 | /* global :: A pointer to retrieved global hints to discard. */
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| 125 | /* */
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| 126 | typedef void
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| 127 | (*FT_AutoHinter_GlobalDoneFunc)( FT_AutoHinter hinter,
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| 128 | void* global );
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| 129 |
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| 130 |
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| 131 | /*************************************************************************/
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| 132 | /* */
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| 133 | /* <FuncType> */
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| 134 | /* FT_AutoHinter_GlobalResetFunc */
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| 135 | /* */
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| 136 | /* <Description> */
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| 137 | /* This function is used to recompute the global metrics in a given */
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| 138 | /* font. This is useful when global font data changes (e.g. Multiple */
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| 139 | /* Masters fonts where blend coordinates change). */
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| 140 | /* */
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| 141 | /* <Input> */
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| 142 | /* hinter :: A handle to the source auto-hinter. */
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| 143 | /* */
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| 144 | /* face :: A handle to the face. */
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| 145 | /* */
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| 146 | typedef void
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| 147 | (*FT_AutoHinter_GlobalResetFunc)( FT_AutoHinter hinter,
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| 148 | FT_Face face );
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| 149 |
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| 150 |
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| 151 | /*************************************************************************/
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| 152 | /* */
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| 153 | /* <FuncType> */
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| 154 | /* FT_AutoHinter_GlyphLoadFunc */
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| 155 | /* */
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| 156 | /* <Description> */
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| 157 | /* This function is used to load, scale, and automatically hint a */
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| 158 | /* glyph from a given face. */
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| 159 | /* */
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| 160 | /* <Input> */
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| 161 | /* face :: A handle to the face. */
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| 162 | /* */
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| 163 | /* glyph_index :: The glyph index. */
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| 164 | /* */
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| 165 | /* load_flags :: The load flags. */
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| 166 | /* */
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| 167 | /* <Note> */
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| 168 | /* This function is capable of loading composite glyphs by hinting */
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| 169 | /* each sub-glyph independently (which improves quality). */
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| 170 | /* */
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| 171 | /* It will call the font driver with FT_Load_Glyph(), with */
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| 172 | /* FT_LOAD_NO_SCALE set. */
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| 173 | /* */
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| 174 | typedef FT_Error
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| 175 | (*FT_AutoHinter_GlyphLoadFunc)( FT_AutoHinter hinter,
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| 176 | FT_GlyphSlot slot,
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| 177 | FT_Size size,
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| 178 | FT_UInt glyph_index,
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| 179 | FT_Int32 load_flags );
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| 180 |
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| 181 |
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| 182 | /*************************************************************************/
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| 183 | /* */
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| 184 | /* <Struct> */
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| 185 | /* FT_AutoHinter_ServiceRec */
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| 186 | /* */
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| 187 | /* <Description> */
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| 188 | /* The auto-hinter module's interface. */
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| 189 | /* */
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| 190 | typedef struct FT_AutoHinter_ServiceRec_
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| 191 | {
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| 192 | FT_AutoHinter_GlobalResetFunc reset_face;
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| 193 | FT_AutoHinter_GlobalGetFunc get_global_hints;
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| 194 | FT_AutoHinter_GlobalDoneFunc done_global_hints;
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| 195 | FT_AutoHinter_GlyphLoadFunc load_glyph;
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| 196 |
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| 197 | } FT_AutoHinter_ServiceRec, *FT_AutoHinter_Service;
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| 198 |
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| 199 |
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| 200 | FT_END_HEADER
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| 201 |
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| 202 | #endif /* __AUTOHINT_H__ */
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| 203 |
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| 204 |
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| 205 | /* END */
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