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      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 
    132