shadowsocks-windows/shadowsocks-csharp/3rd/zxing/Binarizer.cs

/*
* Copyright 2009 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 ZXing.Common;

namespace ZXing
{
   /// <summary> This class hierarchy provides a set of methods to convert luminance data to 1 bit data.
   /// It allows the algorithm to vary polymorphically, for example allowing a very expensive
   /// thresholding technique for servers and a fast one for mobile. It also permits the implementation
   /// to vary, e.g. a JNI version for Android and a Java fallback version for other platforms.
   /// 
   /// <author>dswitkin@google.com (Daniel Switkin)</author>
   /// </summary>
   public abstract class Binarizer
   {
      private readonly LuminanceSource source;

      /// <summary>
      /// Initializes a new instance of the <see cref="Binarizer"/> class.
      /// </summary>
      /// <param name="source">The source.</param>
      protected internal Binarizer(LuminanceSource source)
      {
         if (source == null)
         {
            throw new ArgumentException("Source must be non-null.");
         }
         this.source = source;
      }

      /// <summary>
      /// Gets the luminance source object.
      /// </summary>
      virtual public LuminanceSource LuminanceSource
      {
         get
         {
            return source;
         }
      }

      /// <summary> Converts one row of luminance data to 1 bit data. May actually do the conversion, or return
      /// cached data. Callers should assume this method is expensive and call it as seldom as possible.
      /// This method is intended for decoding 1D barcodes and may choose to apply sharpening.
      /// For callers which only examine one row of pixels at a time, the same BitArray should be reused
      /// and passed in with each call for performance. However it is legal to keep more than one row
      /// at a time if needed.
      /// </summary>
      /// <param name="y">The row to fetch, 0 &lt;= y &lt; bitmap height.</param>
      /// <param name="row">An optional preallocated array. If null or too small, it will be ignored.
      /// If used, the Binarizer will call BitArray.clear(). Always use the returned object.
      /// </param>
      /// <returns> The array of bits for this row (true means black).</returns>
      public abstract BitArray getBlackRow(int y, BitArray row);

      /// <summary> Converts a 2D array of luminance data to 1 bit data. As above, assume this method is expensive
      /// and do not call it repeatedly. This method is intended for decoding 2D barcodes and may or
      /// may not apply sharpening. Therefore, a row from this matrix may not be identical to one
      /// fetched using getBlackRow(), so don't mix and match between them.
      /// </summary>
      /// <returns> The 2D array of bits for the image (true means black).</returns>
      public abstract BitMatrix BlackMatrix { get; }

      /// <summary> Creates a new object with the same type as this Binarizer implementation, but with pristine
      /// state. This is needed because Binarizer implementations may be stateful, e.g. keeping a cache
      /// of 1 bit data. See Effective Java for why we can't use Java's clone() method.
      /// </summary>
      /// <param name="source">The LuminanceSource this Binarizer will operate on.</param>
      /// <returns> A new concrete Binarizer implementation object.</returns>
      public abstract Binarizer createBinarizer(LuminanceSource source);

      /// <summary>
      /// Gets the width of the luminance source object.
      /// </summary>
      public int Width
      {
         get { return source.Width; }
      }

      /// <summary>
      /// Gets the height of the luminance source object.
      /// </summary>
      public int Height
      {
         get { return source.Height; }
      }
   }
}