MultiFormatReader.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 MultiFormatOneDReader = com.google.zxing.oned.MultiFormatOneDReader;
using PDF417Reader = com.google.zxing.pdf417.PDF417Reader;
using QRCodeReader = com.google.zxing.qrcode.QRCodeReader;
using DataMatrixReader = com.google.zxing.datamatrix.DataMatrixReader;
namespace com.google.zxing
{
	
	/// <summary> MultiFormatReader is a convenience class and the main entry point into the library for most uses.
	/// By default it attempts to decode all barcode formats that the library supports. Optionally, you
	/// can provide a hints object to request different behavior, for example only decoding QR codes.
	/// 
	/// </summary>
	/// <author>  Sean Owen
	/// </author>
	/// <author>  dswitkin@google.com (Daniel Switkin)
	/// </author>
	/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 
	/// </author>
	public sealed class MultiFormatReader : Reader
	{
		/// <summary> This method adds state to the MultiFormatReader. By setting the hints once, subsequent calls
		/// to decodeWithState(image) can reuse the same set of readers without reallocating memory. This
		/// is important for performance in continuous scan clients.
		/// 
		/// </summary>
		/// <param name="hints">The set of hints to use for subsequent calls to decode(image)
		/// </param>
		public System.Collections.Hashtable Hints
		{
			set
			{
				this.hints = value;
				
				bool tryHarder = value != null && value.ContainsKey(DecodeHintType.TRY_HARDER);
				System.Collections.ArrayList formats = value == null?null:(System.Collections.ArrayList) value[DecodeHintType.POSSIBLE_FORMATS];
				readers = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
				if (formats != null)
				{
					bool addOneDReader = formats.Contains(BarcodeFormat.UPC_A) || formats.Contains(BarcodeFormat.UPC_E) || formats.Contains(BarcodeFormat.EAN_13) || formats.Contains(BarcodeFormat.EAN_8) || formats.Contains(BarcodeFormat.CODE_39) || formats.Contains(BarcodeFormat.CODE_128) || formats.Contains(BarcodeFormat.ITF);
					// Put 1D readers upfront in "normal" mode
					if (addOneDReader && !tryHarder)
					{
						readers.Add(new MultiFormatOneDReader(value));
					}
					if (formats.Contains(BarcodeFormat.QR_CODE))
					{
						readers.Add(new QRCodeReader());
					}
					if (formats.Contains(BarcodeFormat.DATAMATRIX))
					{
						readers.Add(new DataMatrixReader());
					}
					if (formats.Contains(BarcodeFormat.PDF417))
					{
						readers.Add(new PDF417Reader());
					}
					// At end in "try harder" mode
					if (addOneDReader && tryHarder)
					{
						readers.Add(new MultiFormatOneDReader(value));
					}
				}
				if ((readers.Count == 0))
				{
					if (!tryHarder)
					{
						readers.Add(new MultiFormatOneDReader(value));
					}
					readers.Add(new QRCodeReader());
					
					// TODO re-enable once Data Matrix is ready
					// readers.addElement(new DataMatrixReader());
					
					// TODO: Enable once PDF417 has passed QA
					//readers.addElement(new PDF417Reader());
					
					if (tryHarder)
					{
						readers.Add(new MultiFormatOneDReader(value));
					}
				}
			}
			
		}
		
		private System.Collections.Hashtable hints;
		private System.Collections.ArrayList readers;
		
		/// <summary> This version of decode honors the intent of Reader.decode(BinaryBitmap) in that it
		/// passes null as a hint to the decoders. However, that makes it inefficient to call repeatedly.
		/// Use setHints() followed by decodeWithState() for continuous scan applications.
		/// 
		/// </summary>
		/// <param name="image">The pixel data to decode
		/// </param>
		/// <returns> The contents of the image
		/// </returns>
		/// <throws>  ReaderException Any errors which occurred </throws>
		public Result decode(BinaryBitmap image)
		{
			Hints = null;
			return decodeInternal(image);
		}
		
		/// <summary> Decode an image using the hints provided. Does not honor existing state.
		/// 
		/// </summary>
		/// <param name="image">The pixel data to decode
		/// </param>
		/// <param name="hints">The hints to use, clearing the previous state.
		/// </param>
		/// <returns> The contents of the image
		/// </returns>
		/// <throws>  ReaderException Any errors which occurred </throws>
		public Result decode(BinaryBitmap image, System.Collections.Hashtable hints)
		{
			Hints = hints;
			return decodeInternal(image);
		}
		
		/// <summary> Decode an image using the state set up by calling setHints() previously. Continuous scan
		/// clients will get a <b>large</b> speed increase by using this instead of decode().
		/// 
		/// </summary>
		/// <param name="image">The pixel data to decode
		/// </param>
		/// <returns> The contents of the image
		/// </returns>
		/// <throws>  ReaderException Any errors which occurred </throws>
		public Result decodeWithState(BinaryBitmap image)
		{
			// Make sure to set up the default state so we don't crash
			if (readers == null)
			{
				Hints = null;
			}
			return decodeInternal(image);
		}
		
		private Result decodeInternal(BinaryBitmap image)
		{
			int size = readers.Count;
			for (int i = 0; i < size; i++)
			{
				Reader reader = (Reader) readers[i];
				try
				{
					return reader.decode(image, hints);
				}
				catch (ReaderException re)
				{
					// continue
				}
			}
			
			throw ReaderException.Instance;
		}
	}
}