source/layout/GXLayoutEngine.h

/*
 * @(#)GXLayoutEngine.h	1.4 00/03/15
 *
 * (C) Copyright IBM Corp. 1998, 1999, 2000, 2001 - All Rights Reserved
 *
 */

#ifndef __GXLAYOUTENGINE_H
#define __GXLAYOUTENGINE_H

#include "LETypes.h"
#include "LEFontInstance.h"
#include "LEGlyphFilter.h"
#include "LayoutEngine.h"

#include "MorphTables.h"

U_NAMESPACE_BEGIN

/**
 * This class implements layout for QuickDraw GX or Apple Advanced Typograyph (AAT)
 * fonts. A font is a GX or AAT font if it contains a 'mort' table. See Apple's
 * TrueType Reference Manual (http://fonts.apple.com/TTRefMan/index.html) for details.
 * Information about 'mort' tables is in the chapter titled "Font Files."
 */
class GXLayoutEngine : public LayoutEngine
{
public:
	/**
	 * This is the main constructor. It constructs an instance of GXLayoutEngine for
	 * a particular font, script and language. It takes the 'mort' table as a parameter since
	 * LayoutEngine::layoutEngineFactory has to read the 'mort' table to know that it has a
	 * GX font.
	 *
	 * Note: GX and AAT fonts don't contain any script and language specific tables, so
	 * the script and language are ignored.
	 *
	 * @param fontInstance - the font
	 * @param scriptCode - the script
	 * @param langaugeCode - the language
	 * @param morphTable - the 'mort' table
	 *
	 * @see LayoutEngine::layoutEngineFactory
	 * @see ScriptAndLangaugeTags.h for script and language codes
	 */
    GXLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, const MorphTableHeader *morphTable);

	/**
	 * The destructor, virtual for correct polymorphic invocation.
	 */
    virtual ~GXLayoutEngine();

protected:

	/**
	 * The address of the 'mort' table
	 */
    const MorphTableHeader *fMorphTable;

    /**
	 * This method does GX layout using the font's 'mort' table. It converts the
	 * input character codes to glyph indices using mapCharsToGlyphs, and then
	 * applies the 'mort' table.
	 *
	 * Input parameters:
	 * @param chars - the input character context
	 * @param offset - the index of the first character to process
	 * @param count - the number of characters to process
	 * @param max - the number of characters in the input context
	 * @param rightToLeft - true if the text is in a right to left directional run
	 *
	 * Output parameters:
	 * @param glyphs - the glyph index array
	 * @param charIndices - the character index array
	 * @param success - set to an error code if the operation fails
	 *
	 * @return the number of glyphs in the glyph index array
	 */
    virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
        LEGlyphID *&glyphs, le_int32 *&charIndices, LEErrorCode &success);

    /**
	 * This method adjusts the glyph positions using the font's
	 * 'kern', 'trak', 'bsln', 'opbd' and 'just' tables.
	 *
	 * Input parameters:
	 * @param glyphs - the input glyph array
	 * @param glyphCount - the number of glyphs in the glyph array
	 * @param x - the starting X position
	 * @param y - the starting Y position
	 *
	 * Output parameters:
	 * @param positions - the output X and Y positions (two entries per glyph)
	 * @param success - set to an error code if the operation fails
	 */
    virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphID glyphs[],
        le_int32 glyphCount, float positions[], LEErrorCode &success);
};

U_NAMESPACE_END
#endif