zxing/csharp/datamatrix/DataMatrixReader.cs

using System;
using System.Collections.Generic;
using System.Linq;
using com.google.zxing;
using com.google.zxing.common;
using com.google.zxing.datamatrix.decoder;
using com.google.zxing.datamatrix.detector;

namespace com.google.zxing.datamatrix
{
    public sealed class DataMatrixReader
    {
          private static  ResultPoint[] NO_POINTS = new ResultPoint[0];
          private Decoder decoder = new Decoder();

          /**
           * Locates and decodes a Data Matrix code in an image.
           *
           * @return a String representing the content encoded by the Data Matrix code
           * @throws ReaderException if a Data Matrix code cannot be found, or cannot be decoded
           */
          public Result decode(MonochromeBitmapSource image) {
            return decode(image, null);
          }

          public Result decode(MonochromeBitmapSource image, System.Collections.Hashtable hints)
              {
            DecoderResult decoderResult;
            ResultPoint[] points;
            if (hints != null && hints.ContainsKey(DecodeHintType.PURE_BARCODE)) {
              BitMatrix bits = extractPureBits(image);
              decoderResult = decoder.decode(bits);
              points = NO_POINTS;
            } else {
              DetectorResult detectorResult = new Detector(image).detect();
              decoderResult = decoder.decode(detectorResult.getBits());
              points = detectorResult.getPoints();
            }
            Result result = new Result(decoderResult.getText(), decoderResult.getRawBytes(), points, BarcodeFormat.DATAMATRIX);
            if (decoderResult.getByteSegments() != null) {
              result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.getByteSegments());
            }
            return result;
          }

          /**
           * 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.
           */
          private static BitMatrix extractPureBits(MonochromeBitmapSource image) {
            // Now need to determine module size in pixels

            int height = image.getHeight();
            int width = image.getWidth();
            int minDimension = 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.isBlack(borderWidth, borderWidth)) {
              borderWidth++;
            }
            if (borderWidth == minDimension) {
              throw new ReaderException();
            }

            // And then keep tracking across the top-left black module to determine module size
            int moduleEnd = borderWidth + 1;
            while (moduleEnd < width && image.isBlack(moduleEnd, borderWidth)) {
              moduleEnd++;
            }
            if (moduleEnd == width) {
              throw new ReaderException();
            }

            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.isBlack(borderWidth, columnEndOfSymbol)) {
    	        columnEndOfSymbol--;
            }
            if (columnEndOfSymbol < 0) {
              throw new ReaderException();
            }
            columnEndOfSymbol++;

            // Make sure width of barcode is a multiple of module size
            if ((columnEndOfSymbol - borderWidth) % moduleSize != 0) {
              throw new ReaderException();
            }
            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 new ReaderException();
            }

            // 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.isBlack(borderWidth + j * moduleSize, iOffset)) {
                  bits.set(i, j);
                }
              }
            }
            return bits;
          }
    }
}