194 lines
7.3 KiB
C
194 lines
7.3 KiB
C
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/*
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* @(#)ArabicLayoutEngine.h 1.3 00/03/15
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*
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* (C) Copyright IBM Corp. 1998, 1999, 2000 - All Rights Reserved
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*
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*/
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#ifndef __ARABICLAYOUTENGINE_H
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#define __ARABICLAYOUTENGINE_H
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#include "LETypes.h"
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#include "LEFontInstance.h"
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#include "LEGlyphFilter.h"
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#include "LayoutEngine.h"
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#include "OpenTypeLayoutEngine.h"
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#include "GlyphSubstitutionTables.h"
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#include "GlyphDefinitionTables.h"
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#include "GlyphPositioningTables.h"
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/**
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* This class implements OpenType layout for Arabic fonts. It overrides
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* the characerProcessing method to assign the correct OpenType feature
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* tags for the Arabic contextual forms. It also overrides the adjustGlyphPositions
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* method to guarantee that all vowel and accent glyphs have zero advance width.
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*/
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class ArabicOpenTypeLayoutEngine : public OpenTypeLayoutEngine
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{
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public:
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/**
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* This is the main constructor. It constructs an instance of ArabicOpenTypeLayoutEngine for
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* a particular font, script and language. It takes the GSUB table as a parameter since
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* LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
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* Indic OpenType font.
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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 langaugeCode - the language
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* @param gsubTable - the GSUB table
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*
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* @see LayoutEngine::layoutEngineFactory
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* @see OpenTypeLayoutEngine
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* @see ScriptAndLangaugeTags.h for script and language codes
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*/
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ArabicOpenTypeLayoutEngine(LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
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GlyphSubstitutionTableHeader *gsubTable);
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/**
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* This constructor is used when the font requires a "canned" GSUB table which can't be known
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* until after this constructor has been invoked.
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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 langaugeCode - the language
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*
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* @see OpenTypeLayoutEngine
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* @see ScriptAndLangaugeTags.h for script and language codes
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*/
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ArabicOpenTypeLayoutEngine(LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode);
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/**
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* The destructor, virtual for correct polymorphic invocation.
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*/
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virtual ~ArabicOpenTypeLayoutEngine();
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protected:
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/**
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* This method does Arabic OpenType character processing. It assigns the OpenType feature
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* tags to the characters to generate the correct contextual forms and ligatures.
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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 - true if the characters are in a right to left directional run
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*
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* Output parameters:
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* @param outChars - the output character arrayt
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* @param charIndices - the output character index array
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* @param featureTags - the output feature tag array
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*
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* @return the output character count
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*/
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virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
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LEUnicode *&outChars, le_int32 *&charIndices, const LETag **&featureTags);
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/**
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* This method applies the GPOS table if it is present, otherwise it ensures that all vowel
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* and accent glyphs have a zero advance width by calling the adjustMarkGlyphs method.
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* If the font contains a GDEF table, that is used to identify voewls and accents. Otherwise
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* the character codes are used.
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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 - true if the glyphs in the glyph array have been reordered
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* @param glyphs - the input glyph array
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* @param glyphCount - the number of glyphs
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* @param positions - the position array, will be updated as needed
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*/
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virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphID glyphs[], le_int32 glyphCount, float positions[]);
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};
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/**
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* The class implements OpenType layout for Arabic fonts which don't
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* contain a GSUB table, using a canned GSUB table based on Unicode
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* Arabic Presentation Forms. It overrides the mapCharsToGlyphs method
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* to use the Presentation Forms as logical glyph indices. It overrides the
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* glyphPostProcessing method to convert the Presentation Forms to actual
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* glyph indices.
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*
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* @see ArabicOpenTypeLayoutEngine
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*/
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class UnicodeArabicOpenTypeLayoutEngine : public ArabicOpenTypeLayoutEngine
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{
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public:
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/**
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* This constructs an instance of UnicodeArabicOpenTypeLayoutEngine for a specific font,
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* script and language.
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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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*
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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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UnicodeArabicOpenTypeLayoutEngine(LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode);
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/**
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* The destructor, virtual for correct polymorphic invocation.
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*/
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virtual ~UnicodeArabicOpenTypeLayoutEngine();
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protected:
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/**
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* This method converts the Arabic Presentation Forms in the temp glyph array
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* into actual glyph indices using ArabicOpenTypeLayoutEngine::mapCharsToGlyps.
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*
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* Input paramters:
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* @param tempGlyphs - the input presentation forms
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* @param tempCharIndices - the input character index array
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* @param tempGlyphCount - the number of Presentation Froms
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*
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* Output parameters:
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* @param glyphs - the output glyph index array
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* @param charIndices - the output character index array
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*
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* @return the number of glyph indices in the output glyph index array
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*/
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virtual le_int32 glyphPostProcessing(LEGlyphID tempGlyphs[], le_int32 tempCharIndices[], le_int32 tempGlyphCount,
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LEGlyphID *&glyphs, le_int32 *&charIndices);
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/**
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* This method copies the input characters into the output glyph index array,
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* for use by the canned GSUB table. It also generates the character index array.
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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 offset of the first character to be mapped
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* @param count - the number of characters to be mapped
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* @param reverse - if true, the output will be in reverse order
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* @param mirror - if true, do character mirroring
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*
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* Output parameters:
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* @param glyphs - the glyph array
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* @param charIndices - the character index array
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*/
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virtual void mapCharsToGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, le_bool mirror,
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LEGlyphID *&glyphs, le_int32 *&charIndices);
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/**
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* This method ensures that all vowel and accent glyphs have a zero advance width by calling
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* the adjustMarkGlyphs method. The character codes are used to identify the vowel and mark
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* glyphs.
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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 - true if the glyphs in the glyph array have been reordered
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* @param glyphs - the input glyph array
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* @param glyphCount - the number of glyphs
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* @param positions - the position array, will be updated as needed
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*/
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virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphID glyphs[], le_int32 glyphCount, float positions[]);
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};
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#endif
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