bars2symean.h

barcode readers [ from Image]

//
// Given an array of bar code widths read an EAN bar
// code, if present.
//
// Copyright (C) 2006 by Jon A. Webb
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//

#ifndef Bars2SymEan_h
#define Bars2SymEan_h

#include "Bars2Sym.h"

#include <e32cons.h>
#include <e32math.h>

namespace Barcode
{
	class CBars2SymEan: public CBars2Sym
    {
        // Lifecycle
    public:
        IMPORT_C static CBars2SymEan* NewL();
        ~CBars2SymEan(void);

    private:
		// First-phase constructor
        CBars2SymEan();
		// Second-phase constructor
		void ConstructL();

        // Operations
    public:
        // FindBarsL
		//   Given a barcode image produce an array
		//   representing the string encoded, or return false if nothing was found.
        //
		// Input
		//  pPositions is an array of bar widths
		// Output
		//  pCode is the decoded string
        IMPORT_C bool DecodeL(
			Core::CImage image, 
			CodeType*& pCode);

	private:
		// DecodeFirstDigit
		//    Decode the first digit using the UPC lookup table
		//    and record the digit for use when determining which
		//    parity to use when decoding other digits.
		//    bars is the array of bar widths.
		//    pos is the position of the bars for this digit in the array.
		//    Returns true if the digit was decoded successfully.
		//    Returns decoded digit in 'digit'.
		bool DecodeFirstDigit(CArrayFix<char>& bars, int pos, TChar& digit);

		// DecodeOtherDigits
		//    Decode the other digits using the appropriate parity table
		//    from the first digit. 
		//    bars is the array of bar widths.
		//    pos is the position of the bars for this digit in the array.
		//    Returns true if the digit was decoded successfully.
		//    Returns decoded digit in 'digit'.
		bool DecodeOtherDigits(CArrayFix<char>& bars, int pos, int digitPos, TChar& digit);

		// EncodeBars
		//    Encodes the four bars starting at position pos in bars
		//    as a bit pattern for lookup in the iLookup tables.
		//    Returns the encoded value.
		int EncodeBars(CArrayFix<char>& bars, int pos);

		// Accessors
	public:
		const TDesC& Name() const;
    private:
		// Attributes
		// This is the even parity digit lookup table
		char iLookupEven[128];
		// This is the odd parity digit lookup table
		char iLookupOdd[128];
		// This is the UPC lookup table (used for first digit)
		char iLookupUpc[128];
		// this records the first digit
		int iFirstDigit;
		// this is the mapping from first
		// digit and digit position 
		// to whether this digit uses odd parity or not
		bool iParityOdd[10][6];
    };

};
#endif // Bars2SymEan_h