os/textandloc/fontservices/textshaperplugin/IcuSource/layout/KhmerLayoutEngine.h
author sl
Tue, 10 Jun 2014 14:32:02 +0200
changeset 1 260cb5ec6c19
permissions -rw-r--r--
Update contrib.
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/*
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 *
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 * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved 
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 *
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 * This file is a modification of the ICU file IndicLayoutEngine.h
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 * by Jens Herden and Javier Sola for Khmer language 
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 *
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 */
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#ifndef __KHMERLAYOUTENGINE_H
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#define __KHMERLAYOUTENGINE_H
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// #include "LETypes.h"
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// #include "LEFontInstance.h"
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// #include "LEGlyphFilter.h"
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// #include "LayoutEngine.h"
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// #include "OpenTypeLayoutEngine.h"
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// #include "GlyphSubstitutionTables.h"
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// #include "GlyphDefinitionTables.h"
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// #include "GlyphPositioningTables.h"
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U_NAMESPACE_BEGIN
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// class MPreFixups;
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// class LEGlyphStorage;
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/**
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 * This class implements OpenType layout for Khmer OpenType fonts, as
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 * specified by Microsoft in "Creating and Supporting OpenType Fonts for
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 * Khmer Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm) TODO: change url
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 *
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 * This class overrides the characterProcessing method to do Khmer character processing
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 * and reordering (See the MS spec. for more details)
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 *
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 * @internal
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 */
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class KhmerOpenTypeLayoutEngine : public OpenTypeLayoutEngine
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{
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public:
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    /**
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     * This is the main constructor. It constructs an instance of KhmerOpenTypeLayoutEngine for
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     * a particular font, script and language. It takes the GSUB table as a parameter since
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     * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
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     * Khmer OpenType font.
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     *
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     * @param fontInstance - the font
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     * @param scriptCode - the script
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     * @param langaugeCode - the language
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     * @param gsubTable - the GSUB table
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     *
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     * @see LayoutEngine::layoutEngineFactory
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     * @see OpenTypeLayoutEngine
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     * @see ScriptAndLangaugeTags.h for script and language codes
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     *
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     * @internal
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     */
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    KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
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                            le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable);
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    /**
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     * This constructor is used when the font requires a "canned" GSUB table which can't be known
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     * until after this constructor has been invoked.
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     *
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     * @param fontInstance - the font
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     * @param scriptCode - the script
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     * @param langaugeCode - the language
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     *
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     * @see OpenTypeLayoutEngine
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     * @see ScriptAndLangaugeTags.h for script and language codes
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     *
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     * @internal
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     */
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    KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
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			      le_int32 typoFlags);
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    /**
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     * The destructor, virtual for correct polymorphic invocation.
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     *
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     * @internal
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     */
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   virtual ~KhmerOpenTypeLayoutEngine();
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    /**
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     * ICU "poor man's RTTI", returns a UClassID for the actual class.
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     *
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     * @stable ICU 2.8
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     */
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    virtual UClassID getDynamicClassID() const;
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    /**
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     * ICU "poor man's RTTI", returns a UClassID for this class.
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     *
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     * @stable ICU 2.8
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     */
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    static UClassID getStaticClassID();
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protected:
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    /**
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     * This method does Khmer OpenType character processing. It assigns the OpenType feature
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     * tags to the characters, and may generate output characters which have been reordered. 
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     * It may also split some vowels, resulting in more output characters than input characters.
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     *
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     * Input parameters:
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     * @param chars - the input character context
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     * @param offset - the index of the first character to process
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     * @param count - the number of characters to process
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     * @param max - the number of characters in the input context
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     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
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     * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.
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     *                       the auxillary data array will be set to the feature tags.
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     *
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     * Output parameters:
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     * @param success - set to an error code if the operation fails
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     *
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     * @return the output character count
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     *
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     * @internal
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     */
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    virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
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            LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
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};
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U_NAMESPACE_END
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#endif
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