zxing/csharp/oned/MultiFormatUPCEANReader.cs

/*
* 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.
*/
namespace com.google.zxing.oned
{
    /**
     * @author dswitkin@google.com (Daniel Switkin)
     * @author Sean Owen
     */
    using System.Text;
    using com.google.zxing.common;

    public sealed class MultiFormatUPCEANReader : AbstractOneDReader
    { 
          private  System.Collections.ArrayList readers;
          public MultiFormatUPCEANReader(System.Collections.Hashtable hints) {
            System.Collections.ArrayList possibleFormats = hints == null ? null : (System.Collections.ArrayList) hints[DecodeHintType.POSSIBLE_FORMATS];
            readers = new System.Collections.ArrayList();
            if (possibleFormats != null) {
              if (possibleFormats.Contains(BarcodeFormat.EAN_13)) {
                readers.Add(new EAN13Reader());
              } else if (possibleFormats.Contains(BarcodeFormat.UPC_A)) {
                readers.Add(new UPCAReader());
              }
              if (possibleFormats.Contains(BarcodeFormat.EAN_8)) {
                readers.Add(new EAN8Reader());
              }
              if (possibleFormats.Contains(BarcodeFormat.UPC_E)) {
                readers.Add(new UPCEReader());
              }
            }
            if (readers.Count==0) {
              readers.Add(new EAN13Reader());
              // UPC-A is covered by EAN-13
              readers.Add(new EAN8Reader());
              readers.Add(new UPCEReader());
            }
          }

          public override Result decodeRow(int rowNumber, BitArray row, System.Collections.Hashtable hints) {
            // Compute this location once and reuse it on multiple implementations
            int[] startGuardPattern = AbstractUPCEANReader.findStartGuardPattern(row);
            int size = readers.Count;
            for (int i = 0; i < size; i++) {
              UPCEANReader reader = (UPCEANReader) readers[i];
              Result result;
              try {
                result = reader.decodeRow(rowNumber, row, startGuardPattern);
              } catch (ReaderException re) {
                continue;
              }
              // Special case: a 12-digit code encoded in UPC-A is identical to a "0"
              // followed by those 12 digits encoded as EAN-13. Each will recognize such a code,
              // UPC-A as a 12-digit string and EAN-13 as a 13-digit string starting with "0".
              // Individually these are correct and their readers will both read such a code
              // and correctly call it EAN-13, or UPC-A, respectively.
              //
              // In this case, if we've been looking for both types, we'd like to call it
              // a UPC-A code. But for efficiency we only run the EAN-13 decoder to also read
              // UPC-A. So we special case it here, and convert an EAN-13 result to a UPC-A
              // result if appropriate.
              if (result.getBarcodeFormat().Equals(BarcodeFormat.EAN_13) && result.getText()[0] == '0') {
                return new Result(result.getText().Substring(1), null, result.getResultPoints(), BarcodeFormat.UPC_A);
              }
              return result;
            }

            throw new ReaderException();
          }
    
    }
}