J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 3 | * |
| 4 | * This code is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License version 2 only, as |
| 6 | * published by the Free Software Foundation. Sun designates this |
| 7 | * particular file as subject to the "Classpath" exception as provided |
| 8 | * by Sun in the LICENSE file that accompanied this code. |
| 9 | * |
| 10 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 11 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 12 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 13 | * version 2 for more details (a copy is included in the LICENSE file that |
| 14 | * accompanied this code). |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License version |
| 17 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 18 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 19 | * |
| 20 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 21 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 22 | * have any questions. |
| 23 | * |
| 24 | */ |
| 25 | |
| 26 | |
| 27 | /* |
| 28 | * |
| 29 | * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved |
| 30 | * |
| 31 | */ |
| 32 | |
| 33 | #ifndef __OPENTYPELAYOUTENGINE_H |
| 34 | #define __OPENTYPELAYOUTENGINE_H |
| 35 | |
| 36 | #include "LETypes.h" |
| 37 | #include "LEGlyphFilter.h" |
| 38 | #include "LEFontInstance.h" |
| 39 | #include "LayoutEngine.h" |
| 40 | |
| 41 | #include "GlyphSubstitutionTables.h" |
| 42 | #include "GlyphDefinitionTables.h" |
| 43 | #include "GlyphPositioningTables.h" |
| 44 | |
| 45 | /** |
| 46 | * OpenTypeLayoutEngine implements complex text layout for OpenType fonts - that is |
| 47 | * fonts which have GSUB and GPOS tables associated with them. In order to do this, |
| 48 | * the glyph processsing step described for LayoutEngine is further broken into three |
| 49 | * steps: |
| 50 | * |
| 51 | * 1) Character processing - this step analyses the characters and assigns a list of OpenType |
| 52 | * feature tags to each one. It may also change, remove or add characters, and change |
| 53 | * their order. |
| 54 | * |
| 55 | * 2) Glyph processing - This step performs character to glyph mapping,and uses the GSUB |
| 56 | * table associated with the font to perform glyph substitutions, such as ligature substitution. |
| 57 | * |
| 58 | * 3) Glyph post processing - in cases where the font doesn't directly contain a GSUB table, |
| 59 | * the previous two steps may have generated "fake" glyph indices to use with a "canned" GSUB |
| 60 | * table. This step turns those glyph indices into actual font-specific glyph indices, and may |
| 61 | * perform any other adjustments requried by the previous steps. |
| 62 | * |
| 63 | * OpenTypeLayoutEngine will also use the font's GPOS table to apply position adjustments |
| 64 | * such as kerning and accent positioning. |
| 65 | * |
| 66 | * @see LayoutEngine |
| 67 | * |
| 68 | * @internal |
| 69 | */ |
| 70 | class OpenTypeLayoutEngine : public LayoutEngine |
| 71 | { |
| 72 | public: |
| 73 | /** |
| 74 | * This is the main constructor. It constructs an instance of OpenTypeLayoutEngine for |
| 75 | * a particular font, script and language. It takes the GSUB table as a parameter since |
| 76 | * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an |
| 77 | * OpenType font. |
| 78 | * |
| 79 | * @param fontInstance - the font |
| 80 | * @param scriptCode - the script |
| 81 | * @param langaugeCode - the language |
| 82 | * @param gsubTable - the GSUB table |
| 83 | * |
| 84 | * @see LayoutEngine::layoutEngineFactory |
| 85 | * @see ScriptAndLangaugeTags.h for script and language codes |
| 86 | * |
| 87 | * @internal |
| 88 | */ |
| 89 | OpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, |
| 90 | le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable); |
| 91 | |
| 92 | /** |
| 93 | * This constructor is used when the font requires a "canned" GSUB table which can't be known |
| 94 | * until after this constructor has been invoked. |
| 95 | * |
| 96 | * @param fontInstance - the font |
| 97 | * @param scriptCode - the script |
| 98 | * @param languageCode - the language |
| 99 | * |
| 100 | * @internal |
| 101 | */ |
| 102 | OpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, le_int32 typoFlags); |
| 103 | |
| 104 | /** |
| 105 | * The destructor, virtual for correct polymorphic invocation. |
| 106 | * |
| 107 | * @internal |
| 108 | */ |
| 109 | virtual ~OpenTypeLayoutEngine(); |
| 110 | |
| 111 | /** |
| 112 | * A convenience method used to convert the script code into |
| 113 | * the four byte script tag required by OpenType. |
| 114 | * |
| 115 | * @param scriptCode - the script code |
| 116 | * |
| 117 | * @return the four byte script tag |
| 118 | * |
| 119 | * @internal |
| 120 | */ |
| 121 | static LETag getScriptTag(le_int32 scriptCode); |
| 122 | |
| 123 | /** |
| 124 | * A convenience method used to convert the langauge code into |
| 125 | * the four byte langauge tag required by OpenType. |
| 126 | * |
| 127 | * @param languageCode - the language code |
| 128 | * |
| 129 | * @return the four byte language tag |
| 130 | * |
| 131 | * @internal |
| 132 | */ |
| 133 | static LETag getLangSysTag(le_int32 languageCode); |
| 134 | |
| 135 | private: |
| 136 | |
| 137 | /** |
| 138 | * This method is used by the constructors to convert the script |
| 139 | * and language codes to four byte tags and save them. |
| 140 | */ |
| 141 | void setScriptAndLanguageTags(); |
| 142 | |
| 143 | /** |
| 144 | * The array of script tags, indexed by script code. |
| 145 | */ |
| 146 | static const LETag scriptTags[]; |
| 147 | |
| 148 | /** |
| 149 | * The array of language tags, indexed by language code. |
| 150 | */ |
| 151 | static const LETag languageTags[]; |
| 152 | |
| 153 | protected: |
| 154 | /** |
| 155 | * A set of "default" features. The default characterProcessing method |
| 156 | * will apply all of these features to every glyph. |
| 157 | * |
| 158 | * @internal |
| 159 | */ |
| 160 | FeatureMask fFeatureMask; |
| 161 | |
| 162 | /** |
| 163 | * A set of mappings from feature tags to feature masks. These may |
| 164 | * be in the order in which the featues should be applied, but they |
| 165 | * don't need to be. |
| 166 | * |
| 167 | * @internal |
| 168 | */ |
| 169 | const FeatureMap *fFeatureMap; |
| 170 | |
| 171 | /** |
| 172 | * The length of the feature map. |
| 173 | * |
| 174 | * @internal |
| 175 | */ |
| 176 | le_int32 fFeatureMapCount; |
| 177 | |
| 178 | /** |
| 179 | * <code>TRUE</code> if the features in the |
| 180 | * feature map are in the order in which they |
| 181 | * must be applied. |
| 182 | * |
| 183 | * @internal |
| 184 | */ |
| 185 | le_bool fFeatureOrder; |
| 186 | |
| 187 | /** |
| 188 | * The address of the GSUB table. |
| 189 | * |
| 190 | * @internal |
| 191 | */ |
| 192 | const GlyphSubstitutionTableHeader *fGSUBTable; |
| 193 | |
| 194 | /** |
| 195 | * The address of the GDEF table. |
| 196 | * |
| 197 | * @internal |
| 198 | */ |
| 199 | const GlyphDefinitionTableHeader *fGDEFTable; |
| 200 | |
| 201 | /** |
| 202 | * The address of the GPOS table. |
| 203 | * |
| 204 | * @internal |
| 205 | */ |
| 206 | const GlyphPositioningTableHeader *fGPOSTable; |
| 207 | |
| 208 | /** |
| 209 | * An optional filter used to inhibit substitutions |
| 210 | * preformed by the GSUB table. This is used for some |
| 211 | * "canned" GSUB tables to restrict substitutions to |
| 212 | * glyphs that are in the font. |
| 213 | * |
| 214 | * @internal |
| 215 | */ |
| 216 | LEGlyphFilter *fSubstitutionFilter; |
| 217 | |
| 218 | /** |
| 219 | * The four byte script tag. |
| 220 | * |
| 221 | * @internal |
| 222 | */ |
| 223 | LETag fScriptTag; |
| 224 | |
| 225 | /** |
| 226 | * The four byte language tag |
| 227 | * |
| 228 | * @internal |
| 229 | */ |
| 230 | LETag fLangSysTag; |
| 231 | |
| 232 | /** |
| 233 | * This method does the OpenType character processing. It assigns the OpenType feature |
| 234 | * tags to the characters, and may generate output characters that differ from the input |
| 235 | * charcters due to insertions, deletions, or reorderings. In such cases, it will also |
| 236 | * generate an output character index array reflecting these changes. |
| 237 | * |
| 238 | * Subclasses must override this method. |
| 239 | * |
| 240 | * Input parameters: |
| 241 | * @param chars - the input character context |
| 242 | * @param offset - the index of the first character to process |
| 243 | * @param count - the number of characters to process |
| 244 | * @param max - the number of characters in the input context |
| 245 | * @param rightToLeft - TRUE if the characters are in a right to left directional run |
| 246 | * |
| 247 | * Output parameters: |
| 248 | * @param outChars - the output character array, if different from the input |
| 249 | * @param charIndices - the output character index array |
| 250 | * @param featureTags - the output feature tag array |
| 251 | * @param success - set to an error code if the operation fails |
| 252 | * |
| 253 | * @return the output character count (input character count if no change) |
| 254 | * |
| 255 | * @internal |
| 256 | */ |
| 257 | virtual le_int32 characterProcessing(const LEUnicode /*chars*/[], le_int32 offset, |
| 258 | le_int32 count, le_int32 max, le_bool /*rightToLeft*/, |
| 259 | LEUnicode *&/*outChars*/, LEGlyphStorage &glyphStorage, LEErrorCode &success); |
| 260 | |
| 261 | /** |
| 262 | * This method does character to glyph mapping, and applies the GSUB table. The |
| 263 | * default implementation calls mapCharsToGlyphs and then applies the GSUB table, |
| 264 | * if there is one. |
| 265 | * |
| 266 | * Note that in the case of "canned" GSUB tables, the output glyph indices may be |
| 267 | * "fake" glyph indices that need to be converted to "real" glyph indices by the |
| 268 | * glyphPostProcessing method. |
| 269 | * |
| 270 | * Input parameters: |
| 271 | * @param chars - the input character context |
| 272 | * @param offset - the index of the first character to process |
| 273 | * @param count - the number of characters to process |
| 274 | * @param max - the number of characters in the input context |
| 275 | * @param rightToLeft - TRUE if the characters are in a right to left directional run |
| 276 | * @param featureTags - the feature tag array |
| 277 | * |
| 278 | * Output parameters: |
| 279 | * @param glyphs - the output glyph index array |
| 280 | * @param charIndices - the output character index array |
| 281 | * @param success - set to an error code if the operation fails |
| 282 | * |
| 283 | * @return the number of glyphs in the output glyph index array |
| 284 | * |
| 285 | * Note: if the character index array was already set by the characterProcessing |
| 286 | * method, this method won't change it. |
| 287 | * |
| 288 | * @internal |
| 289 | */ |
| 290 | virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, |
| 291 | le_int32 count, le_int32 max, le_bool rightToLeft, |
| 292 | LEGlyphStorage &glyphStorage, LEErrorCode &success); |
| 293 | |
| 294 | /** |
| 295 | * This method does any processing necessary to convert "fake" |
| 296 | * glyph indices used by the glyphProcessing method into "real" glyph |
| 297 | * indices which can be used to render the text. Note that in some |
| 298 | * cases, such as CDAC Indic fonts, several "real" glyphs may be needed |
| 299 | * to render one "fake" glyph. |
| 300 | * |
| 301 | * The default implementation of this method just returns the input glyph |
| 302 | * index and character index arrays, assuming that no "fake" glyph indices |
| 303 | * were needed to do GSUB processing. |
| 304 | * |
| 305 | * Input paramters: |
| 306 | * @param tempGlyphs - the input "fake" glyph index array |
| 307 | * @param tempCharIndices - the input "fake" character index array |
| 308 | * @param tempGlyphCount - the number of "fake" glyph indices |
| 309 | * |
| 310 | * Output parameters: |
| 311 | * @param glyphs - the output glyph index array |
| 312 | * @param charIndices - the output character index array |
| 313 | * @param success - set to an error code if the operation fails |
| 314 | * |
| 315 | * @return the number of glyph indices in the output glyph index array |
| 316 | * |
| 317 | * @internal |
| 318 | */ |
| 319 | virtual le_int32 glyphPostProcessing(LEGlyphStorage &tempGlyphStorage, |
| 320 | LEGlyphStorage &glyphStorage, LEErrorCode &success); |
| 321 | |
| 322 | /** |
| 323 | * This method applies the characterProcessing, glyphProcessing and glyphPostProcessing |
| 324 | * methods. Most subclasses will not need to override this method. |
| 325 | * |
| 326 | * Input parameters: |
| 327 | * @param chars - the input character context |
| 328 | * @param offset - the index of the first character to process |
| 329 | * @param count - the number of characters to process |
| 330 | * @param max - the number of characters in the input context |
| 331 | * @param rightToLeft - TRUE if the text is in a right to left directional run |
| 332 | * |
| 333 | * Output parameters: |
| 334 | * @param glyphs - the glyph index array |
| 335 | * @param charIndices - the character index array |
| 336 | * @param success - set to an error code if the operation fails |
| 337 | * |
| 338 | * @return the number of glyphs in the glyph index array |
| 339 | * |
| 340 | * @see LayoutEngine::computeGlyphs |
| 341 | * |
| 342 | * @internal |
| 343 | */ |
| 344 | virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, |
| 345 | le_int32 max, le_bool rightToLeft, LEGlyphStorage &glyphStorage, LEErrorCode &success); |
| 346 | |
| 347 | /** |
| 348 | * This method uses the GPOS table, if there is one, to adjust the glyph positions. |
| 349 | * |
| 350 | * Input parameters: |
| 351 | * @param glyphs - the input glyph array |
| 352 | * @param glyphCount - the number of glyphs in the glyph array |
| 353 | * @param x - the starting X position |
| 354 | * @param y - the starting Y position |
| 355 | * |
| 356 | * Output parameters: |
| 357 | * @param positions - the output X and Y positions (two entries per glyph) |
| 358 | * @param success - set to an error code if the operation fails |
| 359 | * |
| 360 | * @internal |
| 361 | */ |
| 362 | virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, |
| 363 | le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success); |
| 364 | |
| 365 | /** |
| 366 | * This method frees the feature tag array so that the |
| 367 | * OpenTypeLayoutEngine can be reused for different text. |
| 368 | * It is also called from our destructor. |
| 369 | * |
| 370 | * @internal |
| 371 | */ |
| 372 | virtual void reset(); |
| 373 | }; |
| 374 | |
| 375 | #endif |