zxing/csharp/datamatrix/DataMatrixReader.cs

/*
* Copyright 2007 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 DecodeHintType = com.google.zxing.DecodeHintType;
using BinaryBitmap = com.google.zxing.BinaryBitmap;
using Reader = com.google.zxing.Reader;
using ReaderException = com.google.zxing.ReaderException;
using Result = com.google.zxing.Result;
using ResultPoint = com.google.zxing.ResultPoint;
using ResultMetadataType = com.google.zxing.ResultMetadataType;
using BitMatrix = com.google.zxing.common.BitMatrix;
using DecoderResult = com.google.zxing.common.DecoderResult;
using DetectorResult = com.google.zxing.common.DetectorResult;
using Decoder = com.google.zxing.datamatrix.decoder.Decoder;
using Detector = com.google.zxing.datamatrix.detector.Detector;
namespace com.google.zxing.datamatrix
{
	
	/// <summary> This implementation can detect and decode Data Matrix codes in an image.
	/// 
	/// </summary>
	/// <author>  bbrown@google.com (Brian Brown)
	/// </author>
	/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 
	/// </author>
	public sealed class DataMatrixReader : Reader
	{
		
		//UPGRADE_NOTE: Final was removed from the declaration of 'NO_POINTS '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private static readonly ResultPoint[] NO_POINTS = new ResultPoint[0];
		
		//UPGRADE_NOTE: Final was removed from the declaration of 'decoder '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private Decoder decoder = new Decoder();
		
		/// <summary> Locates and decodes a Data Matrix code in an image.
		/// 
		/// </summary>
		/// <returns> a String representing the content encoded by the Data Matrix code
		/// </returns>
		/// <throws>  ReaderException if a Data Matrix code cannot be found, or cannot be decoded </throws>
		public Result decode(BinaryBitmap image)
		{
			return decode(image, null);
		}
		
		public Result decode(BinaryBitmap image, System.Collections.Hashtable hints)
		{
			DecoderResult decoderResult;
			ResultPoint[] points;
			if (hints != null && hints.ContainsKey(DecodeHintType.PURE_BARCODE))
			{
				BitMatrix bits = extractPureBits(image.BlackMatrix);
				decoderResult = decoder.decode(bits);
				points = NO_POINTS;
			}
			else
			{
				DetectorResult detectorResult = new Detector(image.BlackMatrix).detect();
				decoderResult = decoder.decode(detectorResult.Bits);
				points = detectorResult.Points;
			}
			Result result = new Result(decoderResult.Text, decoderResult.RawBytes, points, BarcodeFormat.DATAMATRIX);
			if (decoderResult.ByteSegments != null)
			{
				result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.ByteSegments);
			}
			if (decoderResult.ECLevel != null)
			{
				result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, decoderResult.ECLevel.ToString());
			}
			return result;
		}
		
		/// <summary> This method detects a Data Matrix code in a "pure" image -- that is, pure monochrome image
		/// which contains only an unrotated, unskewed, image of a Data Matrix code, with some white border
		/// around it. This is a specialized method that works exceptionally fast in this special
		/// case.
		/// </summary>
		private static BitMatrix extractPureBits(BitMatrix image)
		{
			// Now need to determine module size in pixels
			
			int height = image.Height;
			int width = image.Width;
			int minDimension = System.Math.Min(height, width);
			
			// First, skip white border by tracking diagonally from the top left down and to the right:
			int borderWidth = 0;
			while (borderWidth < minDimension && !image.get_Renamed(borderWidth, borderWidth))
			{
				borderWidth++;
			}
			if (borderWidth == minDimension)
			{
				throw ReaderException.Instance;
			}
			
			// And then keep tracking across the top-left black module to determine module size
			int moduleEnd = borderWidth + 1;
			while (moduleEnd < width && image.get_Renamed(moduleEnd, borderWidth))
			{
				moduleEnd++;
			}
			if (moduleEnd == width)
			{
				throw ReaderException.Instance;
			}
			
			int moduleSize = moduleEnd - borderWidth;
			
			// And now find where the bottommost black module on the first column ends
			int columnEndOfSymbol = height - 1;
			while (columnEndOfSymbol >= 0 && !image.get_Renamed(borderWidth, columnEndOfSymbol))
			{
				columnEndOfSymbol--;
			}
			if (columnEndOfSymbol < 0)
			{
				throw ReaderException.Instance;
			}
			columnEndOfSymbol++;
			
			// Make sure width of barcode is a multiple of module size
			if ((columnEndOfSymbol - borderWidth) % moduleSize != 0)
			{
				throw ReaderException.Instance;
			}
			int dimension = (columnEndOfSymbol - borderWidth) / moduleSize;
			
			// Push in the "border" by half the module width so that we start
			// sampling in the middle of the module. Just in case the image is a
			// little off, this will help recover.
			borderWidth += (moduleSize >> 1);
			
			int sampleDimension = borderWidth + (dimension - 1) * moduleSize;
			if (sampleDimension >= width || sampleDimension >= height)
			{
				throw ReaderException.Instance;
			}
			
			// Now just read off the bits
			BitMatrix bits = new BitMatrix(dimension);
			for (int i = 0; i < dimension; i++)
			{
				int iOffset = borderWidth + i * moduleSize;
				for (int j = 0; j < dimension; j++)
				{
					if (image.get_Renamed(borderWidth + j * moduleSize, iOffset))
					{
						bits.set_Renamed(j, i);
					}
				}
			}
			return bits;
		}
	}
}