shadowsocks-windows/shadowsocks-csharp/3rd/zxing/common/BitMatrix.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;

namespace ZXing.Common
{
   /// <summary>
   ///   <p>Represents a 2D matrix of bits. In function arguments below, and throughout the common
   /// module, x is the column position, and y is the row position. The ordering is always x, y.
   /// The origin is at the top-left.</p>
   ///   <p>Internally the bits are represented in a 1-D array of 32-bit ints. However, each row begins
   /// with a new int. This is done intentionally so that we can copy out a row into a BitArray very
   /// efficiently.</p>
   ///   <p>The ordering of bits is row-major. Within each int, the least significant bits are used first,
   /// meaning they represent lower x values. This is compatible with BitArray's implementation.</p>
   /// </summary>
   /// <author>Sean Owen</author>
   /// <author>dswitkin@google.com (Daniel Switkin)</author>
   public sealed partial class BitMatrix
   {
      private readonly int width;
      private readonly int height;
      private readonly int rowSize;
      private readonly int[] bits;

      /// <returns> The width of the matrix
      /// </returns>
      public int Width
      {
         get
         {
            return width;
         }

      }
      /// <returns> The height of the matrix
      /// </returns>
      public int Height
      {
         get
         {
            return height;
         }

      }

      // A helper to construct a square matrix.
      public BitMatrix(int dimension)
         : this(dimension, dimension)
      {
      }

      public BitMatrix(int width, int height)
      {
         if (width < 1 || height < 1)
         {
            throw new System.ArgumentException("Both dimensions must be greater than 0");
         }
         this.width = width;
         this.height = height;
         this.rowSize = (width + 31) >> 5;
         bits = new int[rowSize * height];
      }

      private BitMatrix(int width, int height, int rowSize, int[] bits)
      {
         this.width = width;
         this.height = height;
         this.rowSize = rowSize;
         this.bits = bits;
      }

      /// <summary> <p>Gets the requested bit, where true means black.</p>
      /// 
      /// </summary>
      /// <param name="x">The horizontal component (i.e. which column)
      /// </param>
      /// <param name="y">The vertical component (i.e. which row)
      /// </param>
      /// <returns> value of given bit in matrix
      /// </returns>
      public bool this[int x, int y]
      {
         get
         {
            int offset = y * rowSize + (x >> 5);
            return (((int)((uint)(bits[offset]) >> (x & 0x1f))) & 1) != 0;
         }
         set
         {
            if (value)
            {
               int offset = y * rowSize + (x >> 5);
               bits[offset] |= 1 << (x & 0x1f);
            }
         }
      }

      /// <summary> <p>Flips the given bit.</p>
      /// 
      /// </summary>
      /// <param name="x">The horizontal component (i.e. which column)
      /// </param>
      /// <param name="y">The vertical component (i.e. which row)
      /// </param>
      public void flip(int x, int y)
      {
         int offset = y * rowSize + (x >> 5);
         bits[offset] ^= 1 << (x & 0x1f);
      }


      /// <summary> <p>Sets a square region of the bit matrix to true.</p>
      /// 
      /// </summary>
      /// <param name="left">The horizontal position to begin at (inclusive)
      /// </param>
      /// <param name="top">The vertical position to begin at (inclusive)
      /// </param>
      /// <param name="width">The width of the region
      /// </param>
      /// <param name="height">The height of the region
      /// </param>
      public void setRegion(int left, int top, int width, int height)
      {
         if (top < 0 || left < 0)
         {
            throw new System.ArgumentException("Left and top must be nonnegative");
         }
         if (height < 1 || width < 1)
         {
            throw new System.ArgumentException("Height and width must be at least 1");
         }
         int right = left + width;
         int bottom = top + height;
         if (bottom > this.height || right > this.width)
         {
            throw new System.ArgumentException("The region must fit inside the matrix");
         }
         for (int y = top; y < bottom; y++)
         {
            int offset = y * rowSize;
            for (int x = left; x < right; x++)
            {
               bits[offset + (x >> 5)] |= 1 << (x & 0x1f);
            }
         }
      }

      /// <summary> A fast method to retrieve one row of data from the matrix as a BitArray.
      /// 
      /// </summary>
      /// <param name="y">The row to retrieve
      /// </param>
      /// <param name="row">An optional caller-allocated BitArray, will be allocated if null or too small
      /// </param>
      /// <returns> The resulting BitArray - this reference should always be used even when passing
      /// your own row
      /// </returns>
      public BitArray getRow(int y, BitArray row)
      {
         if (row == null || row.Size < width)
         {
            row = new BitArray(width);
         }
         else
         {
            row.clear();
         }
         int offset = y * rowSize;
         for (int x = 0; x < rowSize; x++)
         {
            row.setBulk(x << 5, bits[offset + x]);
         }
         return row;
      }

      /// <summary>
      /// Sets the row.
      /// </summary>
      /// <param name="y">row to set</param>
      /// <param name="row">{@link BitArray} to copy from</param>
      public void setRow(int y, BitArray row)
      {
         Array.Copy(row.Array, 0, bits, y * rowSize, rowSize);
      }


      /// <summary>
      /// This is useful in detecting a corner of a 'pure' barcode.
      /// </summary>
      /// <returns>{x,y} coordinate of top-left-most 1 bit, or null if it is all white</returns>
      public int[] getTopLeftOnBit()
      {
         int bitsOffset = 0;
         while (bitsOffset < bits.Length && bits[bitsOffset] == 0)
         {
            bitsOffset++;
         }
         if (bitsOffset == bits.Length)
         {
            return null;
         }
         int y = bitsOffset / rowSize;
         int x = (bitsOffset % rowSize) << 5;

         int theBits = bits[bitsOffset];
         int bit = 0;
         while ((theBits << (31 - bit)) == 0)
         {
            bit++;
         }
         x += bit;
         return new[] { x, y };
      }

      public int[] getBottomRightOnBit()
      {
         int bitsOffset = bits.Length - 1;
         while (bitsOffset >= 0 && bits[bitsOffset] == 0)
         {
            bitsOffset--;
         }
         if (bitsOffset < 0)
         {
            return null;
         }

         int y = bitsOffset / rowSize;
         int x = (bitsOffset % rowSize) << 5;

         int theBits = bits[bitsOffset];
         int bit = 31;

         while (((int)((uint)theBits >> bit)) == 0) // (theBits >>> bit)
         {
            bit--;
         }
         x += bit;

         return new int[] { x, y };
      }

   }
}