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4680 | right-hear | 1 | /***************************************************************************/ |
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, 2006, 2007, 2008, 2010 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 | |||
18 | |||
19 | #ifndef __FTINCREM_H__ |
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20 | #define __FTINCREM_H__ |
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21 | |||
22 | #include |
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23 | #include FT_FREETYPE_H |
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24 | |||
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 | |||
31 | |||
32 | FT_BEGIN_HEADER |
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33 | |||
34 | /*************************************************************************** |
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35 | * |
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36 | * @section: |
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37 | * incremental |
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38 | * |
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39 | * @title: |
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40 | * Incremental Loading |
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41 | * |
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42 | * @abstract: |
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43 | * Custom Glyph Loading. |
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44 | * |
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45 | * @description: |
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46 | * This section contains various functions used to perform so-called |
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47 | * `incremental' glyph loading. This is a mode where all glyphs loaded |
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48 | * from a given @FT_Face are provided by the client application, |
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49 | * |
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50 | * Apart from that, all other tables are loaded normally from the font |
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51 | * file. This mode is useful when FreeType is used within another |
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52 | * engine, e.g., a PostScript Imaging Processor. |
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53 | * |
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54 | * To enable this mode, you must use @FT_Open_Face, passing an |
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55 | * @FT_Parameter with the @FT_PARAM_TAG_INCREMENTAL tag and an |
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56 | * @FT_Incremental_Interface value. See the comments for |
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57 | * @FT_Incremental_InterfaceRec for an example. |
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58 | * |
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59 | */ |
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60 | |||
61 | |||
62 | /*************************************************************************** |
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63 | * |
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64 | * @type: |
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65 | * FT_Incremental |
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66 | * |
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67 | * @description: |
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68 | * An opaque type describing a user-provided object used to implement |
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69 | * `incremental' glyph loading within FreeType. This is used to support |
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70 | * embedded fonts in certain environments (e.g., PostScript interpreters), |
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71 | * where the glyph data isn't in the font file, or must be overridden by |
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72 | * different values. |
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73 | * |
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74 | * @note: |
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75 | * It is up to client applications to create and implement @FT_Incremental |
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76 | * objects, as long as they provide implementations for the methods |
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77 | * @FT_Incremental_GetGlyphDataFunc, @FT_Incremental_FreeGlyphDataFunc |
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78 | * and @FT_Incremental_GetGlyphMetricsFunc. |
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79 | * |
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80 | * See the description of @FT_Incremental_InterfaceRec to understand how |
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81 | * to use incremental objects with FreeType. |
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82 | * |
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83 | */ |
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84 | typedef struct FT_IncrementalRec_* FT_Incremental; |
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85 | |||
86 | |||
87 | /*************************************************************************** |
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88 | * |
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89 | * @struct: |
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90 | * FT_Incremental_MetricsRec |
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91 | * |
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92 | * @description: |
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93 | * A small structure used to contain the basic glyph metrics returned |
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94 | * by the @FT_Incremental_GetGlyphMetricsFunc method. |
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95 | * |
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96 | * @fields: |
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97 | * bearing_x :: |
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98 | * Left bearing, in font units. |
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99 | * |
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100 | * bearing_y :: |
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101 | * Top bearing, in font units. |
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102 | * |
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103 | * advance :: |
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104 | * Horizontal component of glyph advance, in font units. |
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105 | * |
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106 | * advance_v :: |
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107 | * Vertical component of glyph advance, in font units. |
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108 | * |
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109 | * @note: |
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110 | * These correspond to horizontal or vertical metrics depending on the |
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111 | * value of the `vertical' argument to the function |
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112 | * @FT_Incremental_GetGlyphMetricsFunc. |
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113 | * |
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114 | */ |
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115 | typedef struct FT_Incremental_MetricsRec_ |
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116 | { |
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117 | FT_Long bearing_x; |
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118 | FT_Long bearing_y; |
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119 | FT_Long advance; |
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120 | FT_Long advance_v; /* since 2.3.12 */ |
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121 | |||
122 | } FT_Incremental_MetricsRec; |
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123 | |||
124 | |||
125 | /*************************************************************************** |
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126 | * |
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127 | * @struct: |
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128 | * FT_Incremental_Metrics |
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129 | * |
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130 | * @description: |
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131 | * A handle to an @FT_Incremental_MetricsRec structure. |
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132 | * |
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133 | */ |
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134 | typedef struct FT_Incremental_MetricsRec_* FT_Incremental_Metrics; |
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135 | |||
136 | |||
137 | /*************************************************************************** |
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138 | * |
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139 | * @type: |
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140 | * FT_Incremental_GetGlyphDataFunc |
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141 | * |
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142 | * @description: |
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143 | * A function called by FreeType to access a given glyph's data bytes |
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144 | * during @FT_Load_Glyph or @FT_Load_Char if incremental loading is |
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145 | * enabled. |
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146 | * |
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147 | * Note that the format of the glyph's data bytes depends on the font |
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148 | * file format. For TrueType, it must correspond to the raw bytes within |
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149 | * the `glyf' table. For PostScript formats, it must correspond to the |
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150 | * *unencrypted* charstring bytes, without any `lenIV' header. It is |
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151 | * undefined for any other format. |
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152 | * |
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153 | * @input: |
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154 | * incremental :: |
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155 | * Handle to an opaque @FT_Incremental handle provided by the client |
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156 | * application. |
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157 | * |
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158 | * glyph_index :: |
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159 | * Index of relevant glyph. |
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160 | * |
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161 | * @output: |
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162 | * adata :: |
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163 | * A structure describing the returned glyph data bytes (which will be |
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164 | * accessed as a read-only byte block). |
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165 | * |
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166 | * @return: |
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167 | * FreeType error code. 0~means success. |
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168 | * |
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169 | * @note: |
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170 | * If this function returns successfully the method |
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171 | * @FT_Incremental_FreeGlyphDataFunc will be called later to release |
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172 | * the data bytes. |
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173 | * |
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174 | * Nested calls to @FT_Incremental_GetGlyphDataFunc can happen for |
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175 | * compound glyphs. |
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176 | * |
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177 | */ |
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178 | typedef FT_Error |
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179 | (*FT_Incremental_GetGlyphDataFunc)( FT_Incremental incremental, |
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180 | FT_UInt glyph_index, |
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181 | FT_Data* adata ); |
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182 | |||
183 | |||
184 | /*************************************************************************** |
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185 | * |
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186 | * @type: |
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187 | * FT_Incremental_FreeGlyphDataFunc |
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188 | * |
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189 | * @description: |
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190 | * A function used to release the glyph data bytes returned by a |
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191 | * successful call to @FT_Incremental_GetGlyphDataFunc. |
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192 | * |
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193 | * @input: |
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194 | * incremental :: |
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195 | * A handle to an opaque @FT_Incremental handle provided by the client |
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196 | * application. |
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197 | * |
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198 | * data :: |
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199 | * A structure describing the glyph data bytes (which will be accessed |
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200 | * as a read-only byte block). |
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201 | * |
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202 | */ |
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203 | typedef void |
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204 | (*FT_Incremental_FreeGlyphDataFunc)( FT_Incremental incremental, |
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205 | FT_Data* data ); |
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206 | |||
207 | |||
208 | /*************************************************************************** |
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209 | * |
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210 | * @type: |
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211 | * FT_Incremental_GetGlyphMetricsFunc |
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212 | * |
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213 | * @description: |
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214 | * A function used to retrieve the basic metrics of a given glyph index |
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215 | * before accessing its data. This is necessary because, in certain |
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216 | * formats like TrueType, the metrics are stored in a different place from |
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217 | * the glyph images proper. |
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218 | * |
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219 | * @input: |
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220 | * incremental :: |
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221 | * A handle to an opaque @FT_Incremental handle provided by the client |
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222 | * application. |
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223 | * |
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224 | * glyph_index :: |
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225 | * Index of relevant glyph. |
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226 | * |
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227 | * vertical :: |
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228 | * If true, return vertical metrics. |
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229 | * |
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230 | * ametrics :: |
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231 | * This parameter is used for both input and output. |
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232 | * The original glyph metrics, if any, in font units. If metrics are |
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233 | * not available all the values must be set to zero. |
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234 | * |
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235 | * @output: |
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236 | * ametrics :: |
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237 | * The replacement glyph metrics in font units. |
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238 | * |
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239 | */ |
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240 | typedef FT_Error |
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241 | (*FT_Incremental_GetGlyphMetricsFunc) |
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242 | ( FT_Incremental incremental, |
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243 | FT_UInt glyph_index, |
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244 | FT_Bool vertical, |
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245 | FT_Incremental_MetricsRec *ametrics ); |
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246 | |||
247 | |||
248 | /************************************************************************** |
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249 | * |
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250 | * @struct: |
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251 | * FT_Incremental_FuncsRec |
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252 | * |
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253 | * @description: |
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254 | * A table of functions for accessing fonts that load data |
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255 | * incrementally. Used in @FT_Incremental_InterfaceRec. |
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256 | * |
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257 | * @fields: |
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258 | * get_glyph_data :: |
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259 | * The function to get glyph data. Must not be null. |
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260 | * |
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261 | * free_glyph_data :: |
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262 | * The function to release glyph data. Must not be null. |
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263 | * |
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264 | * get_glyph_metrics :: |
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265 | * The function to get glyph metrics. May be null if the font does |
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266 | * not provide overriding glyph metrics. |
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267 | * |
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268 | */ |
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269 | typedef struct FT_Incremental_FuncsRec_ |
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270 | { |
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271 | FT_Incremental_GetGlyphDataFunc get_glyph_data; |
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272 | FT_Incremental_FreeGlyphDataFunc free_glyph_data; |
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273 | FT_Incremental_GetGlyphMetricsFunc get_glyph_metrics; |
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274 | |||
275 | } FT_Incremental_FuncsRec; |
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276 | |||
277 | |||
278 | /*************************************************************************** |
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279 | * |
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280 | * @struct: |
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281 | * FT_Incremental_InterfaceRec |
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282 | * |
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283 | * @description: |
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284 | * A structure to be used with @FT_Open_Face to indicate that the user |
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285 | * wants to support incremental glyph loading. You should use it with |
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286 | * @FT_PARAM_TAG_INCREMENTAL as in the following example: |
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287 | * |
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288 | * { |
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289 | * FT_Incremental_InterfaceRec inc_int; |
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290 | * FT_Parameter parameter; |
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291 | * FT_Open_Args open_args; |
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292 | * |
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293 | * |
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294 | * // set up incremental descriptor |
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295 | * inc_int.funcs = my_funcs; |
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296 | * inc_int.object = my_object; |
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297 | * |
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298 | * // set up optional parameter |
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299 | * parameter.tag = FT_PARAM_TAG_INCREMENTAL; |
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300 | * parameter.data = &inc_int; |
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301 | * |
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302 | * // set up FT_Open_Args structure |
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303 | * open_args.flags = FT_OPEN_PATHNAME | FT_OPEN_PARAMS; |
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304 | * open_args.pathname = my_font_pathname; |
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305 | * open_args.num_params = 1; |
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306 | * open_args.params = ¶meter; // we use one optional argument |
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307 | * |
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308 | * // open the font |
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309 | * error = FT_Open_Face( library, &open_args, index, &face ); |
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310 | * ... |
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311 | * } |
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312 | * |
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313 | */ |
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314 | typedef struct FT_Incremental_InterfaceRec_ |
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315 | { |
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316 | const FT_Incremental_FuncsRec* funcs; |
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317 | FT_Incremental object; |
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318 | |||
319 | } FT_Incremental_InterfaceRec; |
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320 | |||
321 | |||
322 | /*************************************************************************** |
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323 | * |
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324 | * @type: |
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325 | * FT_Incremental_Interface |
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326 | * |
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327 | * @description: |
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328 | * A pointer to an @FT_Incremental_InterfaceRec structure. |
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329 | * |
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330 | */ |
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331 | typedef FT_Incremental_InterfaceRec* FT_Incremental_Interface; |
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332 | |||
333 | |||
334 | /*************************************************************************** |
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335 | * |
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336 | * @constant: |
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337 | * FT_PARAM_TAG_INCREMENTAL |
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338 | * |
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339 | * @description: |
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340 | * A constant used as the tag of @FT_Parameter structures to indicate |
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341 | * an incremental loading object to be used by FreeType. |
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342 | * |
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343 | */ |
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344 | #define FT_PARAM_TAG_INCREMENTAL FT_MAKE_TAG( 'i', 'n', 'c', 'r' ) |
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345 | |||
346 | /* */ |
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347 | |||
348 | FT_END_HEADER |
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349 | |||
350 | #endif /* __FTINCREM_H__ */ |
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351 | |||
352 | |||
353 | /* END */ |