145 lines
4.5 KiB
C++
145 lines
4.5 KiB
C++
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/*
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*
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* (C) Copyright IBM Corp. 1998-2008 - All Rights Reserved
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*
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*/
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#ifndef __THAILAYOUTENGINE_H
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#define __THAILAYOUTENGINE_H
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#include "LETypes.h"
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#include "LEFontInstance.h"
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#include "LayoutEngine.h"
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#include "ThaiShaping.h"
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U_NAMESPACE_BEGIN
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class LEGlyphStorage;
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/**
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* This class implements layout for the Thai script, using the ThaiShapingClass.
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* All existing Thai fonts use an encoding which assigns character codes to all
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* the variant forms needed to display accents and tone marks correctly in context.
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* This class can deal with fonts using the Microsoft, Macintosh, and WorldType encodings.
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*
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* @internal
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*/
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class ThaiLayoutEngine : public LayoutEngine
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{
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public:
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/**
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* This constructs an instance of ThaiLayoutEngine for the given font, script and
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* language. It examines the font, using LEFontInstance::canDisplay, to set fGlyphSet
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* and fErrorChar. (see below)
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*
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* @param fontInstance - the font
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* @param scriptCode - the script
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* @param languageCode - the language
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* @param success - set to an error code if the operation fails
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*
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* @see LEFontInstance
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* @see ScriptAndLanguageTags.h for script and language codes
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*
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* @internal
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*/
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ThaiLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, le_int32 typoFlags, LEErrorCode &success);
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/**
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* The destructor, virtual for correct polymorphic invocation.
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*
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* @internal
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*/
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virtual ~ThaiLayoutEngine();
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/**
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* ICU "poor man's RTTI", returns a UClassID for the actual class.
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*
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* @stable ICU 2.8
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*/
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virtual UClassID getDynamicClassID() const;
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/**
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* ICU "poor man's RTTI", returns a UClassID for this class.
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*
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* @stable ICU 2.8
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*/
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static UClassID getStaticClassID();
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protected:
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/**
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* A small integer indicating which Thai encoding
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* the font uses.
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*
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* @see ThaiShaping
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*
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* @internal
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*/
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le_uint8 fGlyphSet;
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/**
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* The character used as a base for vowels and
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* tone marks that are out of sequence. Usually
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* this will be Unicode 0x25CC, if the font can
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* display it.
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*
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* @see ThaiShaping
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*
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* @internal
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*/
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LEUnicode fErrorChar;
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/**
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* This method performs Thai layout. It calls ThaiShaping::compose to
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* generate the correct contextual character codes, and then calls
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* mapCharsToGlyphs to generate the glyph indices.
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*
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* Input parameters:
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* @param chars - the input character context
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* @param offset - the index of the first character to process
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* @param count - the number of characters to process
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* @param max - the number of characters in the input context
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* @param rightToLeft - <code>TRUE</code> if the text is in a right to left directional run
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* @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
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*
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* Output parameters:
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* @param success - set to an error code if the operation fails
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*
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* @return the number of glyphs in the glyph index array
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*
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* @see ThaiShaping
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*
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* @internal
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*/
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virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
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LEGlyphStorage &glyphStorage, LEErrorCode &success);
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/**
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* This method does positioning adjustments like accent positioning and
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* kerning. The default implementation does nothing. Subclasses needing
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* position adjustments must override this method.
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*
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* Note that this method has both characters and glyphs as input so that
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* it can use the character codes to determine glyph types if that information
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* isn't directly available. (e.g. Some Arabic OpenType fonts don't have a GDEF
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* table)
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*
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* @param chars - the input character context
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* @param offset - the offset of the first character to process
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* @param count - the number of characters to process
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* @param reverse - <code>TRUE</code> if the glyphs in the glyph array have been reordered
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* @param glyphStorage - the object which holds the per-glyph storage. The glyph positions will be
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* adjusted as needed.
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* @param success - output parameter set to an error code if the operation fails
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*
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* @internal
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*/
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virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success);
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};
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U_NAMESPACE_END
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#endif
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