[692] | 1 | /***************************************************************************/
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| 2 | /* */
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| 3 | /* ftincrem.h */
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| 4 | /* */
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| 5 | /* FreeType incremental loading (specification). */
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| 6 | /* */
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| 7 | /* Copyright 2002, 2003 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 | #ifndef __FTINCREM_H__
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| 20 | #define __FTINCREM_H__
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| 21 |
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| 22 | #include <ft2build.h>
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| 23 | #include FT_FREETYPE_H
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| 24 |
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| 25 | #ifdef FREETYPE_H
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| 26 | #error "freetype.h of FreeType 1 has been loaded!"
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| 27 | #error "Please fix the directory search order for header files"
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| 28 | #error "so that freetype.h of FreeType 2 is found first."
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| 29 | #endif
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| 30 |
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| 31 |
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| 32 | FT_BEGIN_HEADER
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| 33 |
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| 34 |
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| 35 | /***************************************************************************
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| 36 | *
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| 37 | * @type:
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| 38 | * FT_Incremental
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| 39 | *
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| 40 | * @description:
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| 41 | * An opaque type describing a user-provided object used to implement
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| 42 | * "incremental" glyph loading within FreeType. This is used to support
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| 43 | * embedded fonts in certain environments (e.g. Postscript interpreters),
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| 44 | * where the glyph data isn't in the font file, or must be overridden by
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| 45 | * different values.
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| 46 | *
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| 47 | * @note:
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| 48 | * It is up to client applications to create and implement @FT_Incremental
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| 49 | * objects, as long as they provide implementations for the methods
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| 50 | * @FT_Incremental_GetGlyphDataFunc, @FT_Incremental_FreeGlyphDataFunc
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| 51 | * and @FT_Incremental_GetGlyphMetricsFunc.
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| 52 | *
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| 53 | * See the description of @FT_Incremental_InterfaceRec to understand how
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| 54 | * to use incremental objects with FreeType.
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| 55 | */
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| 56 | typedef struct FT_IncrementalRec_* FT_Incremental;
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| 57 |
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| 58 |
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| 59 | /***************************************************************************
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| 60 | *
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| 61 | * @struct:
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| 62 | * FT_Incremental_Metrics
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| 63 | *
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| 64 | * @description:
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| 65 | * A small structure used to contain the basic glyph metrics returned
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| 66 | * by the @FT_Incremental_GetGlyphMetricsFunc method.
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| 67 | *
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| 68 | * @fields:
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| 69 | * bearing_x ::
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| 70 | * Left bearing, in font units.
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| 71 | *
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| 72 | * bearing_y ::
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| 73 | * Top bearing, in font units.
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| 74 | *
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| 75 | * advance ::
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| 76 | * Glyph advance, in font units.
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| 77 | *
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| 78 | * @note:
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| 79 | * These correspond to horizontal or vertical metrics depending on the
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| 80 | * value of the 'vertical' argument to the function
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| 81 | * @FT_Incremental_GetGlyphMetricsFunc.
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| 82 | */
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| 83 | typedef struct FT_Incremental_MetricsRec_
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| 84 | {
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| 85 | FT_Long bearing_x;
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| 86 | FT_Long bearing_y;
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| 87 | FT_Long advance;
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| 88 |
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| 89 | } FT_Incremental_MetricsRec, *FT_Incremental_Metrics;
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| 90 |
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| 91 |
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| 92 | /***************************************************************************
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| 93 | *
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| 94 | * @type:
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| 95 | * FT_Incremental_GetGlyphDataFunc
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| 96 | *
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| 97 | * @description:
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| 98 | * A function called by FreeType to access a given glyph's data bytes
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| 99 | * during @FT_Load_Glyph or @FT_Load_Char if incremental loading is
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| 100 | * enabled.
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| 101 | *
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| 102 | * Note that the format of the glyph's data bytes depends on the font
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| 103 | * file format. For TrueType, it must correspond to the raw bytes within
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| 104 | * the 'glyf' table. For Postscript formats, it must correspond to the
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| 105 | * *unencrypted* charstring bytes, without any 'lenIV' header. It is
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| 106 | * undefined for any other format.
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| 107 | *
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| 108 | * @input:
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| 109 | * incremental ::
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| 110 | * Handle to an opaque @FT_Incremental handle provided by the client
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| 111 | * application.
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| 112 | *
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| 113 | * glyph_index ::
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| 114 | * Index of relevant glyph.
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| 115 | *
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| 116 | * @output:
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| 117 | * adata ::
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| 118 | * A structure describing the returned glyph data bytes (which will be
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| 119 | * accessed as a read-only byte block).
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| 120 | *
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| 121 | * @return:
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| 122 | * FreeType error code. 0 means success.
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| 123 | *
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| 124 | * @note:
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| 125 | * If this function returns succesfully the method
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| 126 | * @FT_Incremental_FreeGlyphDataFunc will be called later to release
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| 127 | * the data bytes.
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| 128 | *
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| 129 | * Nested calls to @FT_Incremental_GetGlyphDataFunc can happen for
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| 130 | * compound glyphs.
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| 131 | */
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| 132 | typedef FT_Error
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| 133 | (*FT_Incremental_GetGlyphDataFunc)( FT_Incremental incremental,
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| 134 | FT_UInt glyph_index,
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| 135 | FT_Data* adata );
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| 136 |
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| 137 |
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| 138 | /***************************************************************************
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| 139 | *
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| 140 | * @type:
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| 141 | * FT_Incremental_FreeGlyphDataFunc
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| 142 | *
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| 143 | * @description:
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| 144 | * A function used to release the glyph data bytes returned by a
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| 145 | * successful call to @FT_Incremental_GetGlyphDataFunc.
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| 146 | *
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| 147 | * @input:
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| 148 | * incremental ::
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| 149 | * A handle to an opaque @FT_Incremental handle provided by the client
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| 150 | * application.
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| 151 | *
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| 152 | * data ::
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| 153 | * A structure describing the glyph data bytes (which will be accessed
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| 154 | * as a read-only byte block).
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| 155 | */
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| 156 | typedef void
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| 157 | (*FT_Incremental_FreeGlyphDataFunc)( FT_Incremental incremental,
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| 158 | FT_Data* data );
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| 159 |
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| 160 |
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| 161 | /***************************************************************************
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| 162 | *
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| 163 | * @type:
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| 164 | * FT_Incremental_GetGlyphMetricsFunc
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| 165 | *
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| 166 | * @description:
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| 167 | * A function used to retrieve the basic metrics of a given glyph index
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| 168 | * before accessing its data. This is necessary because, in certain
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| 169 | * formats like TrueType, the metrics are stored in a different place from
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| 170 | * the glyph images proper.
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| 171 | *
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| 172 | * @input:
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| 173 | * incremental ::
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| 174 | * A handle to an opaque @FT_Incremental handle provided by the client
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| 175 | * application.
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| 176 | *
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| 177 | * glyph_index ::
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| 178 | * Index of relevant glyph.
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| 179 | *
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| 180 | * vertical ::
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| 181 | * If true, return vertical metrics.
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| 182 | *
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| 183 | * ametrics ::
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| 184 | * This parameter is used for both input and output.
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| 185 | * The original glyph metrics, if any, in font units. If metrics are
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| 186 | * not available all the values must be set to zero.
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| 187 | *
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| 188 | * @output:
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| 189 | * ametrics ::
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| 190 | * The replacement glyph metrics in font units.
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| 191 | *
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| 192 | */
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| 193 | typedef FT_Error
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| 194 | (*FT_Incremental_GetGlyphMetricsFunc)
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| 195 | ( FT_Incremental incremental,
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| 196 | FT_UInt glyph_index,
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| 197 | FT_Bool vertical,
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| 198 | FT_Incremental_MetricsRec *ametrics );
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| 199 |
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| 200 |
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| 201 | /**************************************************************************
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| 202 | *
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| 203 | * @struct:
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| 204 | * FT_Incremental_FuncsRec
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| 205 | *
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| 206 | * @description:
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| 207 | * A table of functions for accessing fonts that load data
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| 208 | * incrementally. Used in @FT_Incremental_InterfaceRec.
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| 209 | *
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| 210 | * @fields:
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| 211 | * get_glyph_data ::
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| 212 | * The function to get glyph data. Must not be null.
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| 213 | *
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| 214 | * free_glyph_data ::
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| 215 | * The function to release glyph data. Must not be null.
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| 216 | *
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| 217 | * get_glyph_metrics ::
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| 218 | * The function to get glyph metrics. May be null if the font does
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| 219 | * not provide overriding glyph metrics.
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| 220 | */
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| 221 | typedef struct FT_Incremental_FuncsRec_
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| 222 | {
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| 223 | FT_Incremental_GetGlyphDataFunc get_glyph_data;
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| 224 | FT_Incremental_FreeGlyphDataFunc free_glyph_data;
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| 225 | FT_Incremental_GetGlyphMetricsFunc get_glyph_metrics;
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| 226 |
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| 227 | } FT_Incremental_FuncsRec;
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| 228 |
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| 229 |
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| 230 | /***************************************************************************
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| 231 | *
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| 232 | * @struct:
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| 233 | * FT_Incremental_InterfaceRec
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| 234 | *
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| 235 | * @description:
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| 236 | * A structure to be used with @FT_Open_Face to indicate that the user
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| 237 | * wants to support incremental glyph loading. You should use it with
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| 238 | * @FT_PARAM_TAG_INCREMENTAL as in the following example:
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| 239 | *
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| 240 | * {
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| 241 | * FT_Incremental_InterfaceRec inc_int;
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| 242 | * FT_Parameter parameter;
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| 243 | * FT_Open_Args open_args;
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| 244 | *
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| 245 | *
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| 246 | * // set up incremental descriptor
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| 247 | * inc_int.funcs = my_funcs;
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| 248 | * inc_int.object = my_object;
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| 249 | *
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| 250 | * // set up optional parameter
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| 251 | * parameter.tag = FT_PARAM_TAG_INCREMENTAL;
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| 252 | * parameter.data = &inc_int;
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| 253 | *
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| 254 | * // set up FT_Open_Args structure
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| 255 | * open_args.flags = FT_OPEN_PATHNAME | FT_OPEN_PARAMS;
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| 256 | * open_args.pathname = my_font_pathname;
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| 257 | * open_args.num_params = 1;
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| 258 | * open_args.params = ¶meter; // we use one optional argument
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| 259 | *
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| 260 | * // open the font
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| 261 | * error = FT_Open_Face( library, &open_args, index, &face );
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| 262 | * ...
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| 263 | * }
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| 264 | */
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| 265 | typedef struct FT_Incremental_InterfaceRec_
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| 266 | {
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| 267 | const FT_Incremental_FuncsRec* funcs;
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| 268 | FT_Incremental object;
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| 269 |
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| 270 | } FT_Incremental_InterfaceRec;
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| 271 |
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| 272 |
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| 273 | /***************************************************************************
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| 274 | *
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| 275 | * @constant:
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| 276 | * FT_PARAM_TAG_INCREMENTAL
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| 277 | *
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| 278 | * @description:
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| 279 | * A constant used as the tag of @FT_Parameter structures to indicate
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| 280 | * an incremental loading object to be used by FreeType.
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| 281 | *
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| 282 | */
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| 283 | #define FT_PARAM_TAG_INCREMENTAL FT_MAKE_TAG( 'i', 'n', 'c', 'r' )
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| 284 |
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| 285 | /* */
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| 286 |
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| 287 | FT_END_HEADER
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| 288 |
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| 289 | #endif /* __FTINCREM_H__ */
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| 290 |
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| 291 |
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| 292 | /* END */
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