bars2symean.cpp

barcode readers [ from Image]

//
// Bars2SymEan
// Given an array of bar code widths read an EAN bar
// code, if present.
//
// This code was written based on Alexander Bogomolny's page describing the
// EAN barcode: http://www.cut-the-knot.org/do_you_know/BarcodeEncoding.shtml.
//
// 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
//
//

#include "Bars2SymEan.h"

using namespace Barcode;

CBars2SymEan::~CBars2SymEan() 
	{}


	EXPORT_C CBars2SymEan* CBars2SymEan::NewL()
	{
		CBars2SymEan *pMe = new (ELeave) CBars2SymEan();
		CleanupStack::PushL(pMe);
		pMe->ConstructL();
		CleanupStack::Pop(pMe);
		return pMe;
	}

	CBars2SymEan::CBars2SymEan() :	CBars2Sym()
	{
	}

	void CBars2SymEan::ConstructL()
	{
		// In the below, the R codes for the digits are the 1-complements
		// of the L codes. But we encode the R digits by 
		// encoded a white bar as 1 and a black bar as 0
		// so we automatically get the 1-complement without
		// while using the same tables
		int i;
		// initialize table to no successful lookup all characters
		for (i=0; i<128; i++) {
			iLookupOdd[i] = '*';
			iLookupEven[i] = '*';
			iLookupUpc[i] = '*';
		}
		// UPC table
		/*  The (L) codes for the ten digits are:
			0 = 3-2-1-1 = 0001101 = 0x0d
			1 = 2-2-2-1 = 0011001 = 0x19
			2 = 2-2-1-2 = 0011011 = 0x1b
			3 = 1-4-1-1 = 0111101 = 0x3d
			4 = 1-1-3-2 = 0100011 = 0x23
			5 = 1-2-3-1 = 0110001 = 0x31
			6 = 4-1-1-1 = 0000101 = 0x05
			7 = 1-3-1-2 = 0111011 = 0x3b
			8 = 3-1-2-1 = 0001001 = 0x09
			9 = 2-1-1-3 = 0010111 = 0x17
		*/
		const char char0 = 0x0d;
		const char char1 = 0x19;
		const char char2 = 0x1b;
		const char char3 = 0x3d;
		const char char4 = 0x23;
		const char char5 = 0x31;
		const char char6 = 0x05;
		const char char7 = 0x3b;
		const char char8 = 0x09;
		const char char9 = 0x17;
		iLookupUpc[char0] = '0';
		iLookupUpc[char1] = '1';
		iLookupUpc[char2] = '2';
		iLookupUpc[char3] = '3';
		iLookupUpc[char4] = '4';
		iLookupUpc[char5] = '5';
		iLookupUpc[char6] = '6';
		iLookupUpc[char7] = '7';
		iLookupUpc[char8] = '8';
		iLookupUpc[char9] = '9';
		// EAN even parity table
		/*  The left even parity codes for the ten digits are:
			0 = 1-1-2-3 = 0100111 = 0x27
			1 = 1-2-2-2 = 0110011 = 0x33
			2 = 2-2-1-2 = 0011011 = 0x1b
			3 = 1-1-4-1 = 0100001 = 0x21
			4 = 2-3-1-1 = 0011101 = 0x1d
			5 = 1-3-2-1 = 0111001 = 0x39
			6 = 4-1-1-1 = 0000101 = 0x05
			7 = 2-1-3-1 = 0010001 = 0x11
			8 = 3-1-2-1 = 0001001 = 0x09
			9 = 2-1-1-3 = 0010111 = 0x17
		*/
		iLookupEven[0x27] = '0';
		iLookupEven[0x33] = '1';
		iLookupEven[0x1b] = '2';
		iLookupEven[0x21] = '3';
		iLookupEven[0x1d] = '4';
		iLookupEven[0x39] = '5';
		iLookupEven[0x05] = '6';
		iLookupEven[0x11] = '7';
		iLookupEven[0x09] = '8';
		iLookupEven[0x17] = '9';
		// EAN odd parity table
		/*  The left odd parity codes for the ten digits are:
			0 = 3-2-1-1 = 0001101 = 0x0d
			1 = 2-2-2-1 = 0011001 = 0x19
			2 = 2-1-2-2 = 0010011 = 0x13
			3 = 1-4-1-1 = 0111101 = 0x3d
			4 = 1-1-3-2 = 0100011 = 0x23
			5 = 1-2-3-1 = 0110001 = 0x31
			6 = 1-1-1-4 = 0101111 = 0x30
			7 = 1-3-1-2 = 0111011 = 0x3b
			8 = 1-2-1-3 = 0110111 = 0x37
			9 = 3-1-1-2 = 0001011 = 0x0b
		*/
		iLookupOdd[0x0d] = '0';
		iLookupOdd[0x19] = '1';
		iLookupOdd[0x13] = '2';
		iLookupOdd[0x3d] = '3';
		iLookupOdd[0x23] = '4';
		iLookupOdd[0x31] = '5';
		iLookupOdd[0x30] = '6';
		iLookupOdd[0x3b] = '7';
		iLookupOdd[0x37] = '8';
		iLookupOdd[0x0b] = '9';	

		// initialize iParityOdd
		//       row is the first digit from the UPC code
		//       column is the digit position - 1
		//        0       1       2       3       4       5
		// 0    odd   	odd   	odd   	odd   	odd   	odd 
		// 1 	odd 	odd 	even 	odd 	even 	even
		// 2 	odd 	odd 	even 	even 	odd 	even
		// 3 	odd 	odd 	even 	even 	even 	odd
		// 4 	odd 	even 	odd 	odd 	even 	even
		// 5 	odd 	even 	even 	odd 	odd 	even
		// 6 	odd 	even 	even 	even 	odd 	odd
		// 7 	odd 	even 	odd 	even 	odd 	even
		// 8 	odd 	even 	odd 	even 	even 	odd
		// 9 	odd 	even 	even 	odd 	even 	odd
		iParityOdd[0][0] = true; 
		iParityOdd[0][1] = true;
		iParityOdd[0][2] = true;
		iParityOdd[0][3] = true;
		iParityOdd[0][4] = true;
		iParityOdd[0][5] = true;

		iParityOdd[1][0] = true; 
		iParityOdd[1][1] = true;
		iParityOdd[1][2] = false;
		iParityOdd[1][3] = true;
		iParityOdd[1][4] = false;
		iParityOdd[1][5] = false;

		iParityOdd[2][0] = true; 
		iParityOdd[2][1] = true;
		iParityOdd[2][2] = false;
		iParityOdd[2][3] = false;
		iParityOdd[2][4] = true;
		iParityOdd[2][5] = false;

		iParityOdd[3][0] = true; 
		iParityOdd[3][1] = true;
		iParityOdd[3][2] = false;
		iParityOdd[3][3] = false;
		iParityOdd[3][4] = false;
		iParityOdd[3][5] = true;

		iParityOdd[4][0] = true; 
		iParityOdd[4][1] = false;
		iParityOdd[4][2] = true;
		iParityOdd[4][3] = true;
		iParityOdd[4][4] = false;
		iParityOdd[4][5] = false;

		iParityOdd[5][0] = true; 
		iParityOdd[5][1] = false;
		iParityOdd[5][2] = false;
		iParityOdd[5][3] = true;
		iParityOdd[5][4] = true;
		iParityOdd[5][5] = false;

		iParityOdd[6][0] = true; 
		iParityOdd[6][1] = false;
		iParityOdd[6][2] = false;
		iParityOdd[6][3] = false;
		iParityOdd[6][4] = true;
		iParityOdd[6][5] = true;

		iParityOdd[7][0] = true; 
		iParityOdd[7][1] = false;
		iParityOdd[7][2] = true;
		iParityOdd[7][3] = false;
		iParityOdd[7][4] = true;
		iParityOdd[7][5] = false;

		iParityOdd[8][0] = true; 
		iParityOdd[8][1] = false;
		iParityOdd[8][2] = true;
		iParityOdd[8][3] = false;
		iParityOdd[8][4] = false;
		iParityOdd[8][5] = true;

		iParityOdd[9][0] = true; 
		iParityOdd[9][1] = false;
		iParityOdd[9][2] = false;
		iParityOdd[9][3] = true;
		iParityOdd[9][4] = false;
		iParityOdd[9][5] = true;
	}

		// 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 CBars2SymEan::DecodeFirstDigit(CArrayFix<char>& bars, int pos, TChar& digit)
	{
		// look up the code
		digit = iLookupUpc[EncodeBars(bars, pos)];
		if (digit != '*') {
			iFirstDigit = int(digit) - int('0');
			return true;
		} else {
			return false;
		}
	}

		// 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 CBars2SymEan::DecodeOtherDigits(CArrayFix<char>& bars, int pos, int digitPos, TChar& digit)
	{
		if (iParityOdd[iFirstDigit][digitPos]) {
			// odd parity digit
			digit = iLookupOdd[EncodeBars(bars, pos)];
		} else {
			// even parity digit
			digit = iLookupEven[EncodeBars(bars, pos)];
		}
		// now look up the code
		return (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 CBars2SymEan::EncodeBars(CArrayFix<char>& bars, int pos)
	{
		// encode bars as 7-bit number
		int encoded = 0;
		// each group of 4 bars consists of a white bar, black bar, white bar, black bar
		// sequence
		// below encode left (right) bars starting with white (black)
		// encoded white (black) bars as 0 (1)
		unsigned char j;
		for (j=0x00; j<bars[pos]; j++) {
			encoded = encoded << 1;
		}
		// encode black (white) bars as 1 (0)
		for (j=0x00; j<bars[pos+1]; j++) {
			encoded = encoded << 1;
			encoded |= 1;
		}
		// encode white (black) bars as 0 (1)
		for (j=0x00; j<bars[pos+2]; j++) {
			encoded = encoded << 1;
		}
		// encode black (white) bars as 1 (0)
		for (j=0x00; j<bars[pos+3]; j++) {
			encoded = encoded << 1;
				encoded |= 1;
		}
		return encoded;
	}


    IMPORT_C bool CBars2SymEan::DecodeL(
		Core::CImage image, 
		CBars2Sym::CodeType*& pCode)
	{
		return false;
	}

	const TDesC& CBars2SymEan::Name() const
	{
		_LIT(KUpcName, "EAN");
		return KUpcName;
	}