/*

 *

 * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved

 *

 */

#ifndef __INDICLAYOUTENGINE_H

#define __INDICLAYOUTENGINE_H

#include "LETypes.h"

#include "LEFontInstance.h"

#include "LEGlyphFilter.h"

#include "LayoutEngine.h"

#include "OpenTypeLayoutEngine.h"

#include "GlyphSubstitutionTables.h"

#include "GlyphDefinitionTables.h"

#include "GlyphPositioningTables.h"

U_NAMESPACE_BEGIN

class MPreFixups;

class LEGlyphStorage;

/**

 * This class implements OpenType layout for Indic OpenType fonts, as

 * specified by Microsoft in "Creating and Supporting OpenType Fonts for

 * Indic Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm)

 *

 * This class overrides the characterProcessing method to do Indic character processing

 * and reordering, and the glyphProcessing method to implement post-GSUB processing for

 * left matras. (See the MS spec. for more details)

 *

 * @internal

 */

class IndicOpenTypeLayoutEngine : public OpenTypeLayoutEngine

{

public:

    /**

     * This is the main constructor. It constructs an instance of IndicOpenTypeLayoutEngine for

     * a particular font, script and language. It takes the GSUB table as a parameter since

     * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an

     * Indic OpenType font.

     *

     * @param fontInstance - the font

     * @param scriptCode - the script

     * @param langaugeCode - the language

     * @param gsubTable - the GSUB table

     *

     * @see LayoutEngine::layoutEngineFactory

     * @see OpenTypeLayoutEngine

     * @see ScriptAndLangaugeTags.h for script and language codes

     *

     * @internal

     */

    IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,

                            le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable);

    /**

     * This constructor is used when the font requires a "canned" GSUB table which can't be known

     * until after this constructor has been invoked.

     *

     * @param fontInstance - the font

     * @param scriptCode - the script

     * @param langaugeCode - the language

     *

     * @see OpenTypeLayoutEngine

     * @see ScriptAndLangaugeTags.h for script and language codes

     *

     * @internal

     */

    IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,

			      le_int32 typoFlags);

    /**

     * The destructor, virtual for correct polymorphic invocation.

     *

     * @internal

     */

   virtual ~IndicOpenTypeLayoutEngine();

    /**

     * ICU "poor man's RTTI", returns a UClassID for the actual class.

     *

     * @stable ICU 2.8

     */

    virtual UClassID getDynamicClassID() const;

    /**

     * ICU "poor man's RTTI", returns a UClassID for this class.

     *

     * @stable ICU 2.8

     */

    static UClassID getStaticClassID();

protected:

    /**

     * This method does Indic OpenType character processing. It assigns the OpenType feature

     * tags to the characters, and may generate output characters which have been reordered. For

     * some Indic scripts, it may also split some vowels, resulting in more output characters

     * than input characters.

     *

     * Input parameters:

     * @param chars - the input character context

     * @param offset - the index of the first character to process

     * @param count - the number of characters to process

     * @param max - the number of characters in the input context

     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run

     * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.

     *                       the auxillary data array will be set to the feature tags.

     *

     * Output parameters:

     * @param success - set to an error code if the operation fails

     *

     * @return the output character count

     *

     * @internal

     */

    virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,

            LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);

    /**

     * This method does character to glyph mapping, applies the GSUB table and applies

     * any post GSUB fixups for left matras. It calls OpenTypeLayoutEngine::glyphProcessing

     * to do the character to glyph mapping, and apply the GSUB table.

     *

     * Note that in the case of "canned" GSUB tables, the output glyph indices may be

     * "fake" glyph indices that need to be converted to "real" glyph indices by the

     * glyphPostProcessing method.

     *

     * Input parameters:

     * @param chars - the input character context

     * @param offset - the index of the first character to process

     * @param count - the number of characters to process

     * @param max - the number of characters in the input context

     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run

     * @param featureTags - the feature tag array

     * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.

     *

     * Output parameters:

     * @param success - set to an error code if the operation fails

     *

     * @return the number of glyphs in the output glyph index array

     *

     * Note: if the character index array was already set by the characterProcessing

     * method, this method won't change it.

     *

     * @internal

     */

    virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,

            LEGlyphStorage &glyphStorage, LEErrorCode &success);

private:

    MPreFixups *fMPreFixups;

};

U_NAMESPACE_END

#endif