polygon.cs

Sharp Map 用于制作GIS系统S harp Map 用于制作GIS系统S harp Map 用于制作GIS系统

// 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;

namespace SharpMap.Geometries
{
	/// <summary>
	/// A Polygon is a planar Surface, defined by 1 exterior boundary and 0 or more interior boundaries. Each
	/// interior boundary defines a hole in the Polygon.
	/// </summary>
	/// <remarks>
	/// Vertices of rings defining holes in polygons are in the opposite direction of the exterior ring.
	/// </remarks>
	[Serializable]
	public class Polygon : Surface
	{
		private LinearRing _ExteriorRing;
		private List<LinearRing> _InteriorRings;

		/// <summary>
		/// Instatiates a polygon based on one extorier ring and a collection of interior rings.
		/// </summary>
		/// <param name="exteriorRing">Exterior ring</param>
		/// <param name="interiorRings">Interior rings</param>
		public Polygon(LinearRing exteriorRing, List<LinearRing> interiorRings)
		{
			_ExteriorRing = exteriorRing;
			_InteriorRings = interiorRings;
		}

		/// <summary>
		/// Instatiates a polygon based on one extorier ring.
		/// </summary>
		/// <param name="exteriorRing">Exterior ring</param>
		public Polygon(LinearRing exteriorRing) : this(exteriorRing, new List<LinearRing>()) { }

		/// <summary>
		/// Instatiates a polygon
		/// </summary>
		public Polygon() : this(new LinearRing(), new List<LinearRing>()) { }

		/// <summary>
		/// Gets or sets the exterior ring of this Polygon
		/// </summary>
		/// <remarks>This method is supplied as part of the OpenGIS Simple Features Specification</remarks>
		public LinearRing ExteriorRing
		{
			get { return _ExteriorRing; }
			set { _ExteriorRing = value; }
		}

		/// <summary>
		/// Gets or sets the interior rings of this Polygon
		/// </summary>
		public List<LinearRing> InteriorRings
		{
			get { return _InteriorRings; }
			set { _InteriorRings = value; }
		}

		/// <summary>
		/// Returns the Nth interior ring for this Polygon as a LineString
		/// </summary>
		/// <remarks>This method is supplied as part of the OpenGIS Simple Features Specification</remarks>
		/// <param name="N"></param>
		/// <returns></returns>
		public LinearRing InteriorRing(int N)
		{
			return _InteriorRings[N];
		}

		/// <summary>
		/// Returns the number of interior rings in this Polygon
		/// </summary>
		/// <remarks>This method is supplied as part of the OpenGIS Simple Features Specification</remarks>
		/// <returns></returns>
		public int NumInteriorRing
		{
			get { return _InteriorRings.Count; }
		}

		/// <summary>
		/// Transforms the polygon to image coordinates, based on the map
		/// </summary>
		/// <param name="map">Map to base coordinates on</param>
		/// <returns>Polygon in image coordinates</returns>
		public System.Drawing.PointF[] TransformToImage(SharpMap.Map map)
		{

			int vertices = _ExteriorRing.Vertices.Count;
			for (int i = 0; i < _InteriorRings.Count;i++)
				vertices += _InteriorRings[i].Vertices.Count;

			System.Drawing.PointF[] v = new System.Drawing.PointF[vertices];
			for (int i = 0; i < _ExteriorRing.Vertices.Count; i++)
				v[i] = SharpMap.Utilities.Transform.WorldtoMap(_ExteriorRing.Vertices[i], map);
			int j = _ExteriorRing.Vertices.Count;
			for (int k = 0; k < _InteriorRings.Count;k++)
			{
				for (int i = 0; i < _InteriorRings[k].Vertices.Count; i++)
					v[j + i] = SharpMap.Utilities.Transform.WorldtoMap(_InteriorRings[k].Vertices[i], map);
				j += _InteriorRings[k].Vertices.Count;
			}
			return v;
		}



#region "Inherited methods from abstract class Geometry"

		/// <summary>
		/// Determines if this Polygon and the specified Polygon object has the same values
		/// </summary>
		/// <param name="p">Polygon to compare with</param>
		/// <returns></returns>
		public bool Equals(Polygon p)
		{
			if (p == null)
				return false;
			if (!p.ExteriorRing.Equals(this.ExteriorRing))
				return false;
			if (p.InteriorRings.Count != this.InteriorRings.Count)
				return false;
				for (int i = 0; i < p.InteriorRings.Count; i++)
				if (!p.InteriorRings[i].Equals(this.InteriorRings[i]))
					return false;
			return true;
		}

		/// <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()
		{
			int hash = ExteriorRing.GetHashCode(); ;
			for (int i = 0; i < InteriorRings.Count; i++)
				hash = hash ^ InteriorRings[i].GetHashCode();
			return hash;
		}

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