icuSources/layout/KhmerLayoutEngine.h

   1
   2 /*
   3  *
   4  * (C) Copyright IBM Corp. 1998-2008 - 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      * @param success - set to an error code if the operation fails
  53      *
  54      * @see LayoutEngine::layoutEngineFactory
  55      * @see OpenTypeLayoutEngine
  56      * @see ScriptAndLangaugeTags.h for script and language codes
  57      *
  58      * @internal
  59      */
  60     KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  61                             le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable, LEErrorCode &success);
  62
  63     /**
  64      * This constructor is used when the font requires a "canned" GSUB table which can't be known
  65      * until after this constructor has been invoked.
  66      *
  67      * @param fontInstance - the font
  68      * @param scriptCode - the script
  69      * @param langaugeCode - the language
  70      * @param success - set to an error code if the operation fails
  71      *
  72      * @see OpenTypeLayoutEngine
  73      * @see ScriptAndLangaugeTags.h for script and language codes
  74      *
  75      * @internal
  76      */
  77     KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
  78                               le_int32 typoFlags, LEErrorCode &success);
  79
  80     /**
  81      * The destructor, virtual for correct polymorphic invocation.
  82      *
  83      * @internal
  84      */
  85    virtual ~KhmerOpenTypeLayoutEngine();
  86
  87     /**
  88      * ICU "poor man's RTTI", returns a UClassID for the actual class.
  89      *
  90      * @stable ICU 2.8
  91      */
  92     virtual UClassID getDynamicClassID() const;
  93
  94     /**
  95      * ICU "poor man's RTTI", returns a UClassID for this class.
  96      *
  97      * @stable ICU 2.8
  98      */
  99     static UClassID getStaticClassID();
 100
 101 protected:
 102
 103     /**
 104      * This method does Khmer OpenType character processing. It assigns the OpenType feature
 105      * tags to the characters, and may generate output characters which have been reordered.
 106      * It may also split some vowels, resulting in more output characters than input characters.
 107      *
 108      * Input parameters:
 109      * @param chars - the input character context
 110      * @param offset - the index of the first character to process
 111      * @param count - the number of characters to process
 112      * @param max - the number of characters in the input context
 113      * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
 114      * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.
 115      *                       the auxillary data array will be set to the feature tags.
 116      *
 117      * Output parameters:
 118      * @param success - set to an error code if the operation fails
 119      *
 120      * @return the output character count
 121      *
 122      * @internal
 123      */
 124     virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
 125             LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
 126
 127 };
 128
 129 U_NAMESPACE_END
 130 #endif
 131