point.cs

来自「Sharp Map 用于制作GIS系统S harp Map 用于制作GIS系统S」· CS 代码 · 共 222 行

// Copyright 2005, 2006 - Morten Nielsen (www.iter.dk)
//
// This file is part of SharpMap.
// SharpMap is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// SharpMap is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with SharpMap; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization;
using System.Runtime.InteropServices;

namespace SharpMap.Geometries
{
	/// <summary>
	/// A Point is a 0-dimensional geometry and represents a single location in 2D coordinate space. A Point has a x coordinate
	/// value and a y-coordinate value. The boundary of a Point is the empty set.
	/// </summary>
	[Serializable]
	public class Point : Geometry, IComparable<Point>
	{
		private double _X;
		private double _Y;
		private bool _IsEmpty = false;
		/// <summary>
		/// Sets whether this object is empty
		/// </summary>
		protected bool SetIsEmpty
		{
			set { _IsEmpty = value; }
		}

		/// <summary>
		/// Initializes a new Point
		/// </summary>
		/// <param name="x">X coordinate</param>
		/// <param name="y">Y coordinate</param>
		public Point(double x, double y)
		{
			_X = x; _Y = y;
		}

		/// <summary>
		/// Initializes a new empty Point
		/// </summary>
		public Point() : this(0, 0) { _IsEmpty = true; }

		/// <summary>
		/// Returns a point based on degrees, minutes and seconds notation.
		/// For western or southern coordinates, add minus '-' in front of all longitude and/or latitude values
		/// </summary>
		/// <param name="longDegrees">Longitude degrees</param>
		/// <param name="longMinutes">Longitude minutes</param>
		/// <param name="longSeconds">Longitude seconds</param>
		/// <param name="latDegrees">Latitude degrees</param>
		/// <param name="latMinutes">Latitude minutes</param>
		/// <param name="latSeconds">Latitude seconds</param>
		/// <returns>Point</returns>
		public static Point FromDMS(double longDegrees, double longMinutes, double longSeconds,
			double latDegrees, double latMinutes, double latSeconds)
		{
			return new Point(longDegrees + longMinutes / 60 + longSeconds / 3600,
				latDegrees + latMinutes / 60 + latSeconds / 3600);
		}

		/// <summary>
		/// Returns a 2D <see cref="Point"/> instance from this <see cref="Point3D"/>
		/// </summary>
		/// <returns><see cref="Point"/></returns>
		public Point AsPoint()
		{
			return new Point(_X, _Y);
		}

		/// <summary>
		/// Gets or sets the X coordinate of the point
		/// </summary>
		public double X
		{
			get
			{
				if (!_IsEmpty)
					return _X;
				else throw new ApplicationException("Point is empty");
			}
			set { _X = value; _IsEmpty = false; }
		}

		/// <summary>
		/// Gets or sets the Y coordinate of the point
		/// </summary>
		public double Y
		{
			get
			{
				if (!_IsEmpty)
					return _Y;
				else throw new ApplicationException("Point is empty");
			}
			set { _Y = value; _IsEmpty = false; }
		}
		/// <summary>
		/// Returns part of coordinate. Index 0 = X, Index 1 = Y
		/// </summary>
		/// <param name="index"></param>
		/// <returns></returns>
		public virtual double this[uint index]
		{
			get
			{
				if (_IsEmpty)
					throw new ApplicationException("Point is empty");
				else if (index == 0)
					return this.X;
				else if
					(index == 1)
					return this.Y;
				else
					throw (new System.Exception("Point index out of bounds"));
			}
			set
			{
				if (index == 0)
					this.X = value;
				else if (index == 1)
					this.Y = value;
				else
					throw (new System.Exception("Point index out of bounds"));
				_IsEmpty = false;
			}
		}
		/// <summary>
		/// Returns the number of ordinates for this point
		/// </summary>
		public virtual int NumOrdinates
		{
			get { return 2; }
		}
		/// <summary>
		/// Transforms the point to image coordinates, based on the map
		/// </summary>
		/// <param name="map">Map to base coordinates on</param>
		/// <returns>point in image coordinates</returns>
		public System.Drawing.PointF TransformToImage(Map map)
		{
			return SharpMap.Utilities.Transform.WorldtoMap(this, map);
		}

		#region Operators
		/// <summary>
		/// Vector + Vector
		/// </summary>
		/// <param name="v1">Vector</param>
		/// <param name="v2">Vector</param>
		/// <returns></returns>
		public static Point operator +(Point v1, Point v2)
		{ return new Point(v1.X + v2.X, v1.Y + v2.Y); }


		/// <summary>
		/// Vector - Vector
		/// </summary>
		/// <param name="v1">Vector</param>
		/// <param name="v2">Vector</param>
		/// <returns>Cross product</returns>
		public static Point operator -(Point v1, Point v2)
		{ return new Point(v1.X - v2.X, v1.Y - v2.Y); }

		/// <summary>
		/// Vector * Scalar
		/// </summary>
		/// <param name="m">Vector</param>
		/// <param name="d">Scalar (double)</param>
		/// <returns></returns>
		public static Point operator *(Point m, double d)
		{ return new Point(m.X * d, m.Y * d); }

		#endregion

		#region "Inherited methods from abstract class Geometry"

		/// <summary>
		/// Checks whether this instance is spatially equal to the Point 'o'
		/// </summary>
		/// <param name="p">Point to compare to</param>
		/// <returns></returns>
		public virtual bool Equals(Point p)
		{
			return p != null && p.X == _X && p.Y == _Y && this._IsEmpty == p.IsEmpty();
		}

		/// <summary>
		/// Serves as a hash function for a particular type. <see cref="GetHashCode"/> is suitable for use 
		/// in hashing algorithms and data structures like a hash table.
		/// </summary>
		/// <returns>A hash code for the current <see cref="GetHashCode"/>.</returns>
		public override int GetHashCode()
		{
			return _X.GetHashCode() ^ _Y.GetHashCode() ^ _IsEmpty.GetHashCode();
		}

		/// <summary>
		///  The inherent dimension of this Geometry object, which must be less than or equal to the coordinate dimension.
		/// </summary>
		public override int Dimension
		{
			get { return 0; }
		}

		/// <summary>
		/// If true, then this Geometry represents the empty point set,