zxing/csharp/common/GenericResultPoint.cs

/*
* Copyright 2008 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.
*/
namespace com.google.zxing.common
{
    using System;
    using System.Text;

    /// <summary> A class which wraps a 2D array of bytes. The default usage is signed. If you want to use it as a
    /// unsigned container, it's up to you to do byteValue & 0xff at each location.
    /// *
    /// JAVAPORT: I'm not happy about the argument ordering throughout the file, as I always like to have
    /// the horizontal component first, but this is for compatibility with the C++ code. The original
    /// code was a 2D array of ints, but since it only ever gets assigned -1, 0, and 1, I'm going to use
    /// less memory and go with bytes.
    /// *
    /// </summary>
    /// <author>  dswitkin@google.com (Daniel Switkin)
    /// 
    /// </author>
    public sealed class GenericResultPoint : ResultPoint
    { 
          private float posX;
          private float posY;

          public GenericResultPoint(float posX, float posY) {
            this.posX = posX;
            this.posY = posY;
          }

          public float getX() {
            return posX;
          }

          public float getY() {
            return posY;
          }

          public String toString() {
            StringBuilder result = new StringBuilder(25);
            result.Append('(');
            result.Append(posX);
            result.Append(',');
            result.Append(posY);
            result.Append(')');
            return result.ToString();
          }

          public bool equals(Object other) {
            
            if (other.GetType() == typeof(GenericResultPoint)) {
              GenericResultPoint otherPoint = (GenericResultPoint) other;
              return posX == otherPoint.posX && posY == otherPoint.posY;
            }
            return false;
          }

          public int hashCode() {
              return 31 * posX.GetHashCode() + posY.GetHashCode();
          }

            /**
           * <p>Orders an array of three ResultPoints in an order [A,B,C] such that AB < AC and
           * BC < AC and the angle between BC and BA is less than 180 degrees.
           */
          public static void orderBestPatterns(ResultPoint[] patterns) {

            // Find distances between pattern centers
            float zeroOneDistance = distance(patterns[0], patterns[1]);
            float oneTwoDistance = distance(patterns[1], patterns[2]);
            float zeroTwoDistance = distance(patterns[0], patterns[2]);

            ResultPoint pointA, pointB, pointC;
            // Assume one closest to other two is B; A and C will just be guesses at first
            if (oneTwoDistance >= zeroOneDistance && oneTwoDistance >= zeroTwoDistance) {
              pointB = patterns[0];
              pointA = patterns[1];
              pointC = patterns[2];
            } else if (zeroTwoDistance >= oneTwoDistance && zeroTwoDistance >= zeroOneDistance) {
              pointB = patterns[1];
              pointA = patterns[0];
              pointC = patterns[2];
            } else {
              pointB = patterns[2];
              pointA = patterns[0];
              pointC = patterns[1];
            }

            // Use cross product to figure out whether A and C are correct or flipped.
            // This asks whether BC x BA has a positive z component, which is the arrangement
            // we want for A, B, C. If it's negative, then we've got it flipped around and
            // should swap A and C.
            if (crossProductZ(pointA, pointB, pointC) < 0.0f) {
              ResultPoint temp = pointA;
              pointA = pointC;
              pointC = temp;
            }

            patterns[0] = pointA;
            patterns[1] = pointB;
            patterns[2] = pointC;
          }


          /**
           * @return distance between two points
           */
          public static float distance(ResultPoint pattern1, ResultPoint pattern2) {
            float xDiff = pattern1.getX() - pattern2.getX();
            float yDiff = pattern1.getY() - pattern2.getY();
            return (float) Math.Sqrt((double) (xDiff * xDiff + yDiff * yDiff));
          }

          /**
           * Returns the z component of the cross product between vectors BC and BA.
           */
          public static float crossProductZ(ResultPoint pointA, ResultPoint pointB, ResultPoint pointC) {
            float bX = pointB.getX();
            float bY = pointB.getY();
            return ((pointC.getX() - bX) * (pointA.getY() - bY)) - ((pointC.getY() - bY) * (pointA.getX() - bX));
          }     
    
    }
}