icuSources/layout/GXLayoutEngine.h

   1
   2 /*
   3  *
   4  * (C) Copyright IBM Corp. 1998-2004 - 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      *
  46      * @see LayoutEngine::layoutEngineFactory
  47      * @see ScriptAndLangaugeTags.h for script and language codes
  48      *
  49      * @internal
  50      */
  51     GXLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, const MorphTableHeader *morphTable);
  52
  53     /**
  54      * The destructor, virtual for correct polymorphic invocation.
  55      *
  56      * @internal
  57      */
  58     virtual ~GXLayoutEngine();
  59
  60     /**
  61      * ICU "poor man's RTTI", returns a UClassID for the actual class.
  62      *
  63      * @stable ICU 2.8
  64      */
  65     virtual UClassID getDynamicClassID() const;
  66
  67     /**
  68      * ICU "poor man's RTTI", returns a UClassID for this class.
  69      *
  70      * @stable ICU 2.8
  71      */
  72     static UClassID getStaticClassID();
  73
  74 protected:
  75
  76     /**
  77      * The address of the 'mort' table
  78      *
  79      * @internal
  80      */
  81     const MorphTableHeader *fMorphTable;
  82
  83     /**
  84      * This method does GX layout using the font's 'mort' table. It converts the
  85      * input character codes to glyph indices using mapCharsToGlyphs, and then
  86      * applies the 'mort' table.
  87      *
  88      * Input parameters:
  89      * @param chars - the input character context
  90      * @param offset - the index of the first character to process
  91      * @param count - the number of characters to process
  92      * @param max - the number of characters in the input context
  93      * @param rightToLeft - <code>TRUE</code> if the text is in a right to left directional run
  94      * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
  95      *
  96      * Output parameters:
  97      * @param success - set to an error code if the operation fails
  98      *
  99      * @return the number of glyphs in the glyph index array
 100      *
 101      * @internal
 102      */
 103     virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
 104         LEGlyphStorage &glyphStorage, LEErrorCode &success);
 105
 106     /**
 107      * This method adjusts the glyph positions using the font's
 108      * 'kern', 'trak', 'bsln', 'opbd' and 'just' tables.
 109      *
 110      * Input parameters:
 111      * @param glyphStorage - the object holding the glyph storage. The positions will be updated as needed.
 112      *
 113      * Output parameters:
 114      * @param success - set to an error code if the operation fails
 115      *
 116      * @internal
 117      */
 118     virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse,
 119                                       LEGlyphStorage &glyphStorage, LEErrorCode &success);
 120
 121 };
 122
 123 U_NAMESPACE_END
 124 #endif
 125