icuSources/layout/GXLayoutEngine.h

   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