133 lines
5.0 KiB
C++
133 lines
5.0 KiB
C++
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/*
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* @(#)IndicLayoutEngine.h 1.4 00/03/15
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*
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* (C) Copyright IBM Corp. 1998, 1999, 2000, 2001 - All Rights Reserved
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*
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*/
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#ifndef __INDICLAYOUTENGINE_H
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#define __INDICLAYOUTENGINE_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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#include <string.h>
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/**
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* This class implements OpenType layout for Indic OpenType fonts, as
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* specified by Microsoft in "Creating and Supporting OpenType Fonts for
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* Indic Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm)
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*
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* This class overrides the characterProcessing method to do Indic character processing
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* and reordering, and the glyphProcessing method to implement post-GSUB processing for
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* left matras. (See the MS spec. for more details)
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*/
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class IndicOpenTypeLayoutEngine : 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 IndicOpenTypeLayoutEngine 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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IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
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const 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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IndicOpenTypeLayoutEngine(const 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 ~IndicOpenTypeLayoutEngine();
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protected:
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/**
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* This method does Indic OpenType character processing. It assigns the OpenType feature
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* tags to the characters, and may generate output characters which have been reordered. For
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* some Indic scripts, it may also split some vowels, resulting in more output characters
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* than input characters.
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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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* @param success - set to an error code if the operation fails
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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, LEErrorCode &success);
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/**
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* This method does character to glyph mapping, applies the GSUB table and applies
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* any post GSUB fixups for left matras. It calls OpenTypeLayoutEngine::glyphProcessing
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* to do the character to glyph mapping, and apply the GSUB table.
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*
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* Note that in the case of "canned" GSUB tables, the output glyph indices may be
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* "fake" glyph indices that need to be converted to "real" glyph indices by the
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* glyphPostProcessing method.
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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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* @param featureTags - the feature tag array
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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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* @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 output glyph index array
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*
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* Note: if the character index array was already set by the characterProcessing
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* method, this method won't change it.
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*/
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// Input: characters, tags
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// Output: glyphs, char indices
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virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
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const LETag **featureTags, LEGlyphID *&glyphs, le_int32 *&charIndices, LEErrorCode &success);
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};
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#endif
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