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      1 
      2 /*
      3  *
      4  * (C) Copyright IBM Corp. 1998-2008 - All Rights Reserved
      5  *
      6  */
      7 
      8 #ifndef __GXLAYOUTENGINE_H
      9 #define __GXLAYOUTENGINE_H
     10 
     11 #include "LETypes.h"
     12 #include "LayoutEngine.h"
     13 
     14 #include "MorphTables.h"
     15 
     16 U_NAMESPACE_BEGIN
     17 
     18 class LEFontInstance;
     19 class LEGlyphStorage;
     20 
     21 /**
     22  * This class implements layout for QuickDraw GX or Apple Advanced Typograyph (AAT)
     23  * fonts. A font is a GX or AAT font if it contains a 'mort' table. See Apple's
     24  * TrueType Reference Manual (http://fonts.apple.com/TTRefMan/index.html) for details.
     25  * Information about 'mort' tables is in the chapter titled "Font Files."
     26  *
     27  * @internal
     28  */
     29 class GXLayoutEngine : public LayoutEngine
     30 {
     31 public:
     32     /**
     33      * This is the main constructor. It constructs an instance of GXLayoutEngine for
     34      * a particular font, script and language. It takes the 'mort' table as a parameter since
     35      * LayoutEngine::layoutEngineFactory has to read the 'mort' table to know that it has a
     36      * GX font.
     37      *
     38      * Note: GX and AAT fonts don't contain any script and language specific tables, so
     39      * the script and language are ignored.
     40      *
     41      * @param fontInstance - the font
     42      * @param scriptCode - the script
     43      * @param langaugeCode - the language
     44      * @param morphTable - the 'mort' table
     45      * @param success - set to an error code if the operation fails
     46      *
     47      * @see LayoutEngine::layoutEngineFactory
     48      * @see ScriptAndLangaugeTags.h for script and language codes
     49      *
     50      * @internal
     51      */
     52     GXLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, const MorphTableHeader *morphTable, LEErrorCode &success);
     53 
     54     /**
     55      * The destructor, virtual for correct polymorphic invocation.
     56      *
     57      * @internal
     58      */
     59     virtual ~GXLayoutEngine();
     60 
     61     /**
     62      * ICU "poor man's RTTI", returns a UClassID for the actual class.
     63      *
     64      * @stable ICU 2.8
     65      */
     66     virtual UClassID getDynamicClassID() const;
     67 
     68     /**
     69      * ICU "poor man's RTTI", returns a UClassID for this class.
     70      *
     71      * @stable ICU 2.8
     72      */
     73     static UClassID getStaticClassID();
     74 
     75 protected:
     76 
     77     /**
     78      * The address of the 'mort' table
     79      *
     80      * @internal
     81      */
     82     const MorphTableHeader *fMorphTable;
     83 
     84     /**
     85      * This method does GX layout using the font's 'mort' table. It converts the
     86      * input character codes to glyph indices using mapCharsToGlyphs, and then
     87      * applies the 'mort' table.
     88      *
     89      * Input parameters:
     90      * @param chars - the input character context
     91      * @param offset - the index of the first character to process
     92      * @param count - the number of characters to process
     93      * @param max - the number of characters in the input context
     94      * @param rightToLeft - <code>TRUE</code> if the text is in a right to left directional run
     95      * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
     96      *
     97      * Output parameters:
     98      * @param success - set to an error code if the operation fails
     99      *
    100      * @return the number of glyphs in the glyph index array
    101      *
    102      * @internal
    103      */
    104     virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
    105         LEGlyphStorage &glyphStorage, LEErrorCode &success);
    106 
    107     /**
    108      * This method adjusts the glyph positions using the font's
    109      * 'kern', 'trak', 'bsln', 'opbd' and 'just' tables.
    110      *
    111      * Input parameters:
    112      * @param glyphStorage - the object holding the glyph storage. The positions will be updated as needed.
    113      *
    114      * Output parameters:
    115      * @param success - set to an error code if the operation fails
    116      *
    117      * @internal
    118      */
    119     virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse,
    120                                       LEGlyphStorage &glyphStorage, LEErrorCode &success);
    121 
    122 };
    123 
    124 U_NAMESPACE_END
    125 #endif
    126 
    127