CoordinateCompare.cs :  » GIS » DeepEarth » GisSharpBlog » NetTopologySuite » Utilities » C# / CSharp Open Source

using System;
using System.Collections;
using GeoAPI.Geometries;

namespace GisSharpBlog.NetTopologySuite.Utilities{
  /// <summary>
  /// CoordinateCompare is used in the sorting of arrays of Coordinate objects.
  /// Implements a lexicographic comparison.
  /// </summary>
  public class CoordinateCompare : IComparer
  {
    /// <summary>
    /// Constructor.
    /// </summary>
    public CoordinateCompare() { }

    /// <summary>
    /// Compares two object and returns a value indicating whether one is less than, equal to or greater
    /// than the other.
    /// </summary>
    /// <param name="x">First Coordinate object to compare.</param>
    /// <param name="y">Second Coordinate object to compare.</param>
    /// <returns>
    ///&lt;table cellspacing="0" class="dtTABLE"&gt;
    ///&lt;TR VALIGN="top"&gt;
    ///   &lt;TH width=50%&gt;Value&lt;/TH&gt;
    ///&lt;TH width=50%&gt;Condition&lt;/TH&gt;
    ///&lt;/TR&gt;
    ///&lt;TR VALIGN="top"&gt;
    ///   &lt;TD width=50%&gt;Less than zero&lt;/TD&gt;
    ///&lt;TD width=50%&gt;&lt;I&gt;a&lt;/I&gt; is less than &lt;I&gt;b&lt;/I&gt;.&lt;/TD&gt;
    ///&lt;/TR&gt;
    ///&lt;TR VALIGN="top"&gt;
    ///   &lt;TD width=50%&gt;Zero&lt;/TD&gt;
    ///&lt;TD width=50%&gt;&lt;I&gt;a&lt;/I&gt; equals &lt;I&gt;b&lt;/I&gt;.&lt;/TD&gt;
    ///&lt;/TR&gt;
    ///&lt;TR VALIGN="top"&gt;
    ///   &lt;TD width=50%&gt;Greater than zero&lt;/TD&gt;
    ///&lt;TD width=50%&gt;&lt;I&gt;a&lt;/I&gt; is greater than &lt;I&gt;b&lt;/I&gt;.&lt;/TD&gt;
    ///&lt;/TR&gt;
    ///&lt;/table&gt;
    /// </returns>
    /// <remarks>If a implements IComparable, then a. CompareTo (b) is returned; otherwise, if b 
    /// implements IComparable, then b. CompareTo (a) is returned.
    /// Comparing a null reference (Nothing in Visual Basic) with any type is allowed and does not
    /// generate an exception when using IComparable. When sorting, a null reference (Nothing) is 
    /// considered to be less than any other object.
    /// </remarks>
    public int Compare(object x, object y)
    {
      int returnValue = 0;
            if (x is ICoordinate && y is  ICoordinate)
            {
      
          ICoordinate coord1 = (ICoordinate) x;
                ICoordinate coord2 = (ICoordinate) y;
        if (coord1.X < coord2.X) 
          returnValue = -1;
        else if (coord1.X > coord2.X) 
          returnValue = 1;
        else if (coord1.Y < coord2.Y) 
          returnValue = -1;
        else if (coord1.Y > coord2.Y) 
          returnValue = 1;
        else returnValue = 0;
      }
      else throw new ArgumentException("Wrong arguments type: ICoordinate expected");
      return returnValue;
    }
  }
}