zxing/csharp/oned/UPCEReader.cs

/*
* Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using BarcodeFormat = com.google.zxing.BarcodeFormat;
using ReaderException = com.google.zxing.ReaderException;
using BitArray = com.google.zxing.common.BitArray;
namespace com.google.zxing.oned
{
	
	/// <summary> <p>Implements decoding of the UPC-E format.</p>
	/// <p/>
	/// <p><a href="http://www.barcodeisland.com/upce.phtml">This</a> is a great reference for
	/// UPC-E information.</p>
	/// 
	/// </summary>
	/// <author>  Sean Owen
	/// </author>
	/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 
	/// </author>
	public sealed class UPCEReader:UPCEANReader
	{
		override internal BarcodeFormat BarcodeFormat
		{
			get
			{
				return BarcodeFormat.UPC_E;
			}
			
		}
		
		/// <summary> The pattern that marks the middle, and end, of a UPC-E pattern.
		/// There is no "second half" to a UPC-E barcode.
		/// </summary>
		//UPGRADE_NOTE: Final was removed from the declaration of 'MIDDLE_END_PATTERN'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private static readonly int[] MIDDLE_END_PATTERN = new int[]{1, 1, 1, 1, 1, 1};
		
		/// <summary> See {@link #L_AND_G_PATTERNS}; these values similarly represent patterns of
		/// even-odd parity encodings of digits that imply both the number system (0 or 1)
		/// used, and the check digit.
		/// </summary>
		//UPGRADE_NOTE: Final was removed from the declaration of 'NUMSYS_AND_CHECK_DIGIT_PATTERNS'. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private static readonly int[][] NUMSYS_AND_CHECK_DIGIT_PATTERNS = new int[][]{new int[]{0x38, 0x34, 0x32, 0x31, 0x2C, 0x26, 0x23, 0x2A, 0x29, 0x25}, new int[]{0x07, 0x0B, 0x0D, 0x0E, 0x13, 0x19, 0x1C, 0x15, 0x16, 0x1A}};
		
		//UPGRADE_NOTE: Final was removed from the declaration of 'decodeMiddleCounters '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private int[] decodeMiddleCounters;
		
		public UPCEReader()
		{
			decodeMiddleCounters = new int[4];
		}
		
		protected internal override int decodeMiddle(BitArray row, int[] startRange, System.Text.StringBuilder result)
		{
			int[] counters = decodeMiddleCounters;
			counters[0] = 0;
			counters[1] = 0;
			counters[2] = 0;
			counters[3] = 0;
			int end = row.Size;
			int rowOffset = startRange[1];
			
			int lgPatternFound = 0;
			
			for (int x = 0; x < 6 && rowOffset < end; x++)
			{
				int bestMatch = decodeDigit(row, counters, rowOffset, L_AND_G_PATTERNS);
				result.Append((char) ('0' + bestMatch % 10));
				for (int i = 0; i < counters.Length; i++)
				{
					rowOffset += counters[i];
				}
				if (bestMatch >= 10)
				{
					lgPatternFound |= 1 << (5 - x);
				}
			}
			
			determineNumSysAndCheckDigit(result, lgPatternFound);
			
			return rowOffset;
		}
		
		protected internal override int[] decodeEnd(BitArray row, int endStart)
		{
			return findGuardPattern(row, endStart, true, MIDDLE_END_PATTERN);
		}
		
		protected internal override bool checkChecksum(System.String s)
		{
			return base.checkChecksum(convertUPCEtoUPCA(s));
		}
		
		private static void  determineNumSysAndCheckDigit(System.Text.StringBuilder resultString, int lgPatternFound)
		{
			
			for (int numSys = 0; numSys <= 1; numSys++)
			{
				for (int d = 0; d < 10; d++)
				{
					if (lgPatternFound == NUMSYS_AND_CHECK_DIGIT_PATTERNS[numSys][d])
					{
						resultString.Insert(0, (char) ('0' + numSys));
						resultString.Append((char) ('0' + d));
						return ;
					}
				}
			}
			throw ReaderException.Instance;
		}
		
		/// <summary> Expands a UPC-E value back into its full, equivalent UPC-A code value.
		/// 
		/// </summary>
		/// <param name="upce">UPC-E code as string of digits
		/// </param>
		/// <returns> equivalent UPC-A code as string of digits
		/// </returns>
		public static System.String convertUPCEtoUPCA(System.String upce)
		{
			char[] upceChars = new char[6];
			SupportClass.GetCharsFromString(upce, 1, 7, upceChars, 0);
			System.Text.StringBuilder result = new System.Text.StringBuilder(12);
			result.Append(upce[0]);
			char lastChar = upceChars[5];
			switch (lastChar)
			{
				
				case '0': 
				case '1': 
				case '2': 
					result.Append(upceChars, 0, 2);
					result.Append(lastChar);
					result.Append("0000");
					result.Append(upceChars, 2, 3);
					break;
				
				case '3': 
					result.Append(upceChars, 0, 3);
					result.Append("00000");
					result.Append(upceChars, 3, 2);
					break;
				
				case '4': 
					result.Append(upceChars, 0, 4);
					result.Append("00000");
					result.Append(upceChars[4]);
					break;
				
				default: 
					result.Append(upceChars, 0, 5);
					result.Append("0000");
					result.Append(lastChar);
					break;
				
			}
			result.Append(upce[7]);
			return result.ToString();
		}
	}
}