207 lines
7.7 KiB
C++
207 lines
7.7 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 - 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(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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IndicOpenTypeLayoutEngine(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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*
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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 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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*
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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);
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};
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#if 0
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/**
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* This class implements Indic OpenType layout for CDAC fonts. Since CDAC fonts don't contain
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* a GSUB table, it uses a canned GSUB table, using logical glyph indices. Each logical glyph
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* may be rendered with several physical glyphs in the CDAC font. It uses the CDACLayout class
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* to do the layout.
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*
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* @see CDACLayout
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* @see IndicOpenTypeLayout
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*/
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class CDACOpenTypeLayoutEngine : public IndicOpenTypeLayoutEngine
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{
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public:
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/**
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* This constructs an instance of CDACOpenTypeLayoutEngine for a specific font, script and
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* language. The scriptInfo parameter contains the information that CDACLayout needs to
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* layout using the font, including the character to logical glyph mapping information,
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* the canned GSUB table, and the map from logical to physical glyphs. This will be obtained
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* by LayoutEngine::layoutEngineFactory to determine if the font is a CDAC 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 languageCode - the language
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* @param scriptInfo - the CDAC script information
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*
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* @see LEFontInstance
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* @see CDACLayout
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* @see ScriptAndLanguageTags.h for script and language codes
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*/
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CDACOpenTypeLayoutEngine(LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
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const CDACLayout::ScriptInfo *scriptInfo);
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/**
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* The destructor, virtual for correct polymorphic invocation.
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*/
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virtual ~CDACOpenTypeLayoutEngine();
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protected:
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const CDACLayout::ScriptInfo *fScriptInfo;
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/**
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* This method converts logical glyph indices to physical glyph indices.
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*
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* Input paramters:
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* @param tempGlyphs - the input "fake" glyph index array
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* @param tempCharIndices - the input "fake" character index array
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* @param tempGlyphCount - the number of "fake" glyph indices
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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 maps charcters to logical 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 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 should be in reverse order
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* @param mirror - if true, map characters like parenthesis to their mirror image
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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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#endif
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#endif
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