icuSources/layout/ThaiLayoutEngine.h

   1
   2 /*
   3  *
   4  * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved
   5  *
   6  */
   7
   8 #ifndef __THAILAYOUTENGINE_H
   9 #define __THAILAYOUTENGINE_H
  10
  11 #include "LETypes.h"
  12 #include "LEFontInstance.h"
  13 #include "LayoutEngine.h"
  14
  15 #include "ThaiShaping.h"
  16
  17 U_NAMESPACE_BEGIN
  18
  19 class LEGlyphStorage;
  20
  21 /**
  22  * This class implements layout for the Thai script, using the ThaiShapingClass.
  23  * All existing Thai fonts use an encoding which assigns character codes to all
  24  * the variant forms needed to display accents and tone marks correctly in context.
  25  * This class can deal with fonts using the Microsoft, Macintosh, and WorldType encodings.
  26  *
  27  * @internal
  28  */
  29 class ThaiLayoutEngine : public LayoutEngine
  30 {
  31 public:
  32     /**
  33      * This constructs an instance of ThaiLayoutEngine for the given font, script and
  34      * language. It examines the font, using LEFontInstance::canDisplay, to set fGlyphSet
  35      * and fErrorChar. (see below)
  36      *
  37      * @param fontInstance - the font
  38      * @param scriptCode - the script
  39      * @param languageCode - the language
  40      *
  41      * @see LEFontInstance
  42      * @see ScriptAndLanguageTags.h for script and language codes
  43      *
  44      * @internal
  45      */
  46     ThaiLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode);
  47
  48     /**
  49      * The destructor, virtual for correct polymorphic invocation.
  50      *
  51      * @internal
  52      */
  53     virtual ~ThaiLayoutEngine();
  54
  55     /**
  56      * ICU "poor man's RTTI", returns a UClassID for the actual class.
  57      *
  58      * @stable ICU 2.8
  59      */
  60     virtual UClassID getDynamicClassID() const;
  61
  62     /**
  63      * ICU "poor man's RTTI", returns a UClassID for this class.
  64      *
  65      * @stable ICU 2.8
  66      */
  67     static UClassID getStaticClassID();
  68
  69 protected:
  70     /**
  71      * A small integer indicating which Thai encoding
  72      * the font uses.
  73      *
  74      * @see ThaiShaping
  75      *
  76      * @internal
  77      */
  78     le_uint8 fGlyphSet;
  79
  80     /**
  81      * The character used as a base for vowels and
  82      * tone marks that are out of sequence. Usually
  83      * this will be Unicode 0x25CC, if the font can
  84      * display it.
  85      *
  86      * @see ThaiShaping
  87      *
  88      * @internal
  89      */
  90     LEUnicode fErrorChar;
  91
  92     /**
  93      * This method performs Thai layout. It calls ThaiShaping::compose to
  94      * generate the correct contextual character codes, and then calls
  95      * mapCharsToGlyphs to generate the glyph indices.
  96      *
  97      * Input parameters:
  98      * @param chars - the input character context
  99      * @param offset - the index of the first character to process
 100      * @param count - the number of characters to process
 101      * @param max - the number of characters in the input context
 102      * @param rightToLeft - <code>TRUE</code> if the text is in a right to left directional run
 103      * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
 104      *
 105      * Output parameters:
 106      * @param success - set to an error code if the operation fails
 107      *
 108      * @return the number of glyphs in the glyph index array
 109      *
 110      * @see ThaiShaping
 111      *
 112      * @internal
 113      */
 114     virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
 115         LEGlyphStorage &glyphStorage, LEErrorCode &success);
 116
 117 };
 118
 119 U_NAMESPACE_END
 120 #endif
 121