icuSources/layout/KhmerLayoutEngine.h

   1
   2 /*
   3  *
   4  * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved
   5  *
   6  * This file is a modification of the ICU file IndicLayoutEngine.h
   7  * by Jens Herden and Javier Sola for Khmer language
   8  *
   9  */
  10
  11 #ifndef __KHMERLAYOUTENGINE_H
  12 #define __KHMERLAYOUTENGINE_H
  13
  14 // #include "LETypes.h"
  15 // #include "LEFontInstance.h"
  16 // #include "LEGlyphFilter.h"
  17 // #include "LayoutEngine.h"
  18 // #include "OpenTypeLayoutEngine.h"
  19
  20 // #include "GlyphSubstitutionTables.h"
  21 // #include "GlyphDefinitionTables.h"
  22 // #include "GlyphPositioningTables.h"
  23
  24 U_NAMESPACE_BEGIN
  25
  26 // class MPreFixups;
  27 // class LEGlyphStorage;
  28
  29 /**
  30  * This class implements OpenType layout for Khmer OpenType fonts, as
  31  * specified by Microsoft in "Creating and Supporting OpenType Fonts for
  32  * Khmer Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm) TODO: change url
  33  *
  34  * This class overrides the characterProcessing method to do Khmer character processing
  35  * and reordering (See the MS spec. for more details)
  36  *
  37  * @internal
  38  */
  39 class KhmerOpenTypeLayoutEngine : public OpenTypeLayoutEngine
  40 {
  41 public:
  42     /**
  43      * This is the main constructor. It constructs an instance of KhmerOpenTypeLayoutEngine for
  44      * a particular font, script and language. It takes the GSUB table as a parameter since
  45      * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
  46      * Khmer OpenType font.
  47      *
  48      * @param fontInstance - the font
  49      * @param scriptCode - the script
  50      * @param langaugeCode - the language
  51      * @param gsubTable - the GSUB table
  52      *
  53      * @see LayoutEngine::layoutEngineFactory
  54      * @see OpenTypeLayoutEngine
  55      * @see ScriptAndLangaugeTags.h for script and language codes
  56      *
  57      * @internal
  58      */
  59     KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  60                             le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable);
  61
  62     /**
  63      * This constructor is used when the font requires a "canned" GSUB table which can't be known
  64      * until after this constructor has been invoked.
  65      *
  66      * @param fontInstance - the font
  67      * @param scriptCode - the script
  68      * @param langaugeCode - the language
  69      *
  70      * @see OpenTypeLayoutEngine
  71      * @see ScriptAndLangaugeTags.h for script and language codes
  72      *
  73      * @internal
  74      */
  75     KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  76                               le_int32 typoFlags);
  77
  78     /**
  79      * The destructor, virtual for correct polymorphic invocation.
  80      *
  81      * @internal
  82      */
  83    virtual ~KhmerOpenTypeLayoutEngine();
  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 Khmer OpenType character processing. It assigns the OpenType feature
 103      * tags to the characters, and may generate output characters which have been reordered.
 104      * It may also split some vowels, resulting in more output characters than input characters.
 105      *
 106      * Input parameters:
 107      * @param chars - the input character context
 108      * @param offset - the index of the first character to process
 109      * @param count - the number of characters to process
 110      * @param max - the number of characters in the input context
 111      * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
 112      * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.
 113      *                       the auxillary data array will be set to the feature tags.
 114      *
 115      * Output parameters:
 116      * @param success - set to an error code if the operation fails
 117      *
 118      * @return the output character count
 119      *
 120      * @internal
 121      */
 122     virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
 123             LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 124
 125 };
 126
 127 U_NAMESPACE_END
 128 #endif
 129