/*

  *

  * (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