icuSources/layout/ArabicLayoutEngine.h

   1
   2 /*
   3  *
   4  * (C) Copyright IBM Corp. 1998-2008 - All Rights Reserved
   5  *
   6  */
   7
   8 #ifndef __ARABICLAYOUTENGINE_H
   9 #define __ARABICLAYOUTENGINE_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 /**
  24  * This class implements OpenType layout for Arabic fonts. It overrides
  25  * the characerProcessing method to assign the correct OpenType feature
  26  * tags for the Arabic contextual forms. It also overrides the adjustGlyphPositions
  27  * method to guarantee that all vowel and accent glyphs have zero advance width.
  28  *
  29  * @internal
  30  */
  31 class ArabicOpenTypeLayoutEngine : public OpenTypeLayoutEngine
  32 {
  33 public:
  34     /**
  35      * This is the main constructor. It constructs an instance of ArabicOpenTypeLayoutEngine for
  36      * a particular font, script and language. It takes the GSUB table as a parameter since
  37      * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
  38      * Indic OpenType font.
  39      *
  40      * @param fontInstance - the font
  41      * @param scriptCode - the script
  42      * @param langaugeCode - the language
  43      * @param gsubTable - the GSUB table
  44      * @param success - set to an error code if the operation fails
  45      *
  46      * @see LayoutEngine::layoutEngineFactory
  47      * @see OpenTypeLayoutEngine
  48      * @see ScriptAndLanguageTags.h for script and language codes
  49      *
  50      * @internal
  51      */
  52     ArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  53                             le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable, LEErrorCode &success);
  54
  55     /**
  56      * This constructor is used when the font requires a "canned" GSUB table which can't be known
  57      * until after this constructor has been invoked.
  58      *
  59      * @param fontInstance - the font
  60      * @param scriptCode - the script
  61      * @param langaugeCode - the language
  62      * @param success - set to an error code if the operation fails
  63      *
  64      * @see OpenTypeLayoutEngine
  65      * @see ScriptAndLanguageTags.h for script and language codes
  66      *
  67      * @internal
  68      */
  69     ArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  70                                le_int32 typoFlags, LEErrorCode &success);
  71
  72     /**
  73      * The destructor, virtual for correct polymorphic invocation.
  74      *
  75      * @internal
  76      */
  77     virtual ~ArabicOpenTypeLayoutEngine();
  78
  79     /**
  80      * ICU "poor man's RTTI", returns a UClassID for the actual class.
  81      *
  82      * @stable ICU 2.8
  83      */
  84     virtual UClassID getDynamicClassID() const;
  85
  86     /**
  87      * ICU "poor man's RTTI", returns a UClassID for this class.
  88      *
  89      * @stable ICU 2.8
  90      */
  91     static UClassID getStaticClassID();
  92
  93 protected:
  94
  95     /**
  96      * This method does Arabic OpenType character processing. It assigns the OpenType feature
  97      * tags to the characters to generate the correct contextual forms and ligatures.
  98      *
  99      * Input parameters:
 100      * @param chars - the input character context
 101      * @param offset - the index of the first character to process
 102      * @param count - the number of characters to process
 103      * @param max - the number of characters in the input context
 104      * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
 105      *
 106      * Output parameters:
 107      * @param outChars - the output character arrayt
 108      * @param charIndices - the output character index array
 109      * @param featureTags - the output feature tag array
 110      * @param success - set to an error code if the operation fails
 111      *
 112      * @return the output character count
 113      *
 114      * @internal
 115      */
 116     virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
 117             LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 118
 119     /**
 120      * This method applies the GPOS table if it is present, otherwise it ensures that all vowel
 121      * and accent glyphs have a zero advance width by calling the adjustMarkGlyphs method.
 122      * If the font contains a GDEF table, that is used to identify voewls and accents. Otherwise
 123      * the character codes are used.
 124      *
 125      * @param chars - the input character context
 126      * @param offset - the offset of the first character to process
 127      * @param count - the number of characters to process
 128      * @param reverse - <code>TRUE</code> if the glyphs in the glyph array have been reordered
 129      * @param glyphs - the input glyph array
 130      * @param glyphCount - the number of glyphs
 131      * @param positions - the position array, will be updated as needed
 132      * @param success - output parameter set to an error code if the operation fails
 133      *
 134      * @internal
 135      */
 136     virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 137
 138     // static void adjustMarkGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool rightToLeft, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 139
 140 };
 141
 142 /**
 143  * The class implements OpenType layout for Arabic fonts which don't
 144  * contain a GSUB table, using a canned GSUB table based on Unicode
 145  * Arabic Presentation Forms. It overrides the mapCharsToGlyphs method
 146  * to use the Presentation Forms as logical glyph indices. It overrides the
 147  * glyphPostProcessing method to convert the Presentation Forms to actual
 148  * glyph indices.
 149  *
 150  * @see ArabicOpenTypeLayoutEngine
 151  *
 152  * @internal
 153  */
 154 class UnicodeArabicOpenTypeLayoutEngine : public ArabicOpenTypeLayoutEngine
 155 {
 156 public:
 157     /**
 158      * This constructs an instance of UnicodeArabicOpenTypeLayoutEngine for a specific font,
 159      * script and language.
 160      *
 161      * @param fontInstance - the font
 162      * @param scriptCode - the script
 163      * @param languageCode - the language
 164      * @param success - set to an error code if the operation fails
 165      *
 166      * @see LEFontInstance
 167      * @see ScriptAndLanguageTags.h for script and language codes
 168      *
 169      * @internal
 170      */
 171     UnicodeArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
 172                 le_int32 typoFlags, LEErrorCode &success);
 173
 174     /**
 175      * The destructor, virtual for correct polymorphic invocation.
 176      *
 177      * @internal
 178      */
 179     virtual ~UnicodeArabicOpenTypeLayoutEngine();
 180
 181 protected:
 182
 183     /**
 184      * This method converts the Arabic Presentation Forms in the temp glyph array
 185      * into actual glyph indices using ArabicOpenTypeLayoutEngine::mapCharsToGlyps.
 186      *
 187      * Input paramters:
 188      * @param tempGlyphs - the input presentation forms
 189      * @param tempCharIndices - the input character index array
 190      * @param tempGlyphCount - the number of Presentation Froms
 191      *
 192      * Output parameters:
 193      * @param glyphs - the output glyph index array
 194      * @param charIndices - the output character index array
 195      * @param success - set to an error code if the operation fails
 196      *
 197      * @return the number of glyph indices in the output glyph index array
 198      *
 199      * @internal
 200      */
 201     virtual le_int32 glyphPostProcessing(LEGlyphStorage &tempGlyphStorage, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 202
 203     /**
 204      * This method copies the input characters into the output glyph index array,
 205      * for use by the canned GSUB table. It also generates the character index array.
 206      *
 207      * Input parameters:
 208      * @param chars - the input character context
 209      * @param offset - the offset of the first character to be mapped
 210      * @param count - the number of characters to be mapped
 211      * @param reverse - if <code>TRUE</code>, the output will be in reverse order
 212      * @param mirror - if <code>TRUE</code>, do character mirroring
 213      * @param glyphStorage - the glyph storage object. Glyph and char index arrays will be updated.
 214      *
 215      * @param success - set to an error code if the operation fails
 216      *
 217      * @internal
 218      */
 219     virtual void mapCharsToGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, le_bool mirror,
 220         LEGlyphStorage &glyphStorage, LEErrorCode &success);
 221
 222     /**
 223      * This method ensures that all vowel and accent glyphs have a zero advance width by calling
 224      * the adjustMarkGlyphs method. The character codes are used to identify the vowel and mark
 225      * glyphs.
 226      *
 227      * @param chars - the input character context
 228      * @param offset - the offset of the first character to process
 229      * @param count - the number of characters to process
 230      * @param reverse - <code>TRUE</code> if the glyphs in the glyph array have been reordered
 231      * @param glyphStorage - the glyph storage object. The glyph positions will be updated as needed.
 232      * @param success - output parameter set to an error code if the operation fails
 233      *
 234      * @internal
 235      */
 236     virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 237 };
 238
 239 U_NAMESPACE_END
 240 #endif
 241