1 2 /* 3 * 4 * (C) Copyright IBM Corp. 1998-2009 - All Rights Reserved 5 * 6 */ 7 8 #ifndef __INDICLAYOUTENGINE_H 9 #define __INDICLAYOUTENGINE_H 10 11 #include "LETypes.h" 12 #include "LEFontInstance.h" 13 #include "LEGlyphFilter.h" 14 #include "LayoutEngine.h" 15 #include "OpenTypeLayoutEngine.h" 16 17 #include "GlyphSubstitutionTables.h" 18 #include "GlyphDefinitionTables.h" 19 #include "GlyphPositioningTables.h" 20 21 U_NAMESPACE_BEGIN 22 23 class MPreFixups; 24 class LEGlyphStorage; 25 26 /** 27 * This class implements OpenType layout for Indic OpenType fonts, as 28 * specified by Microsoft in "Creating and Supporting OpenType Fonts for 29 * Indic Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm) 30 * 31 * This class overrides the characterProcessing method to do Indic character processing 32 * and reordering, and the glyphProcessing method to implement post-GSUB processing for 33 * left matras. (See the MS spec. for more details) 34 * 35 * @internal 36 */ 37 class IndicOpenTypeLayoutEngine : public OpenTypeLayoutEngine 38 { 39 public: 40 /** 41 * This is the main constructor. It constructs an instance of IndicOpenTypeLayoutEngine for 42 * a particular font, script and language. It takes the GSUB table as a parameter since 43 * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an 44 * Indic OpenType font. 45 * 46 * @param fontInstance - the font 47 * @param scriptCode - the script 48 * @param langaugeCode - the language 49 * @param gsubTable - the GSUB table 50 * @param success - set to an error code if the operation fails 51 * 52 * @see LayoutEngine::layoutEngineFactory 53 * @see OpenTypeLayoutEngine 54 * @see ScriptAndLangaugeTags.h for script and language codes 55 * 56 * @internal 57 */ 58 IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, 59 le_int32 typoFlags, le_bool version2, const GlyphSubstitutionTableHeader *gsubTable, LEErrorCode &success); 60 61 /** 62 * This constructor is used when the font requires a "canned" GSUB table which can't be known 63 * until after this constructor has been invoked. 64 * 65 * @param fontInstance - the font 66 * @param scriptCode - the script 67 * @param langaugeCode - the language 68 * @param success - set to an error code if the operation fails 69 * 70 * @see OpenTypeLayoutEngine 71 * @see ScriptAndLangaugeTags.h for script and language codes 72 * 73 * @internal 74 */ 75 IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, 76 le_int32 typoFlags, LEErrorCode &success); 77 78 /** 79 * The destructor, virtual for correct polymorphic invocation. 80 * 81 * @internal 82 */ 83 virtual ~IndicOpenTypeLayoutEngine(); 84 85 /** 86 * ICU "poor man's RTTI", returns a UClassID for the actual class. 87 * 88 * @stable ICU 2.8 89 */ 90 virtual UClassID getDynamicClassID() const; 91 92 /** 93 * ICU "poor man's RTTI", returns a UClassID for this class. 94 * 95 * @stable ICU 2.8 96 */ 97 static UClassID getStaticClassID(); 98 99 protected: 100 101 /** 102 * This method does Indic OpenType character processing. It assigns the OpenType feature 103 * tags to the characters, and may generate output characters which have been reordered. For 104 * some Indic scripts, it may also split some vowels, resulting in more output characters 105 * than input characters. 106 * 107 * Input parameters: 108 * @param chars - the input character context 109 * @param offset - the index of the first character to process 110 * @param count - the number of characters to process 111 * @param max - the number of characters in the input context 112 * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run 113 * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set. 114 * the auxillary data array will be set to the feature tags. 115 * 116 * Output parameters: 117 * @param success - set to an error code if the operation fails 118 * 119 * @return the output character count 120 * 121 * @internal 122 */ 123 virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft, 124 LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success); 125 126 /** 127 * This method does character to glyph mapping, applies the GSUB table and applies 128 * any post GSUB fixups for left matras. It calls OpenTypeLayoutEngine::glyphProcessing 129 * to do the character to glyph mapping, and apply the GSUB table. 130 * 131 * Note that in the case of "canned" GSUB tables, the output glyph indices may be 132 * "fake" glyph indices that need to be converted to "real" glyph indices by the 133 * glyphPostProcessing method. 134 * 135 * Input parameters: 136 * @param chars - the input character context 137 * @param offset - the index of the first character to process 138 * @param count - the number of characters to process 139 * @param max - the number of characters in the input context 140 * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run 141 * @param featureTags - the feature tag array 142 * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set. 143 * 144 * Output parameters: 145 * @param success - set to an error code if the operation fails 146 * 147 * @return the number of glyphs in the output glyph index array 148 * 149 * Note: if the character index array was already set by the characterProcessing 150 * method, this method won't change it. 151 * 152 * @internal 153 */ 154 virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft, 155 LEGlyphStorage &glyphStorage, LEErrorCode &success); 156 157 le_bool fVersion2; 158 159 private: 160 161 MPreFixups *fMPreFixups; 162 163 }; 164 165 U_NAMESPACE_END 166 #endif 167 168
