labelcollisiondetection.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 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.Rendering
{
	/// <summary>
	/// Class defining delegate for label collision detection and static predefined methods
	/// </summary>
	public class LabelCollisionDetection
	{
		/// <summary>
		/// Delegate method for filtering labels. Useful for performing custom collision detection on labels
		/// </summary>
		/// <param name="labels"></param>
		/// <returns></returns>
		public delegate void LabelFilterMethod(List<SharpMap.Rendering.Label> labels);

		#region Label filter methods
		/// <summary>
		/// Simple and fast label collision detection.
		/// </summary>
		/// <param name="labels"></param>
		public static void SimpleCollisionDetection(List<SharpMap.Rendering.Label> labels)
		{
			labels.Sort(); // sort labels by intersectiontests of labelbox
			//remove labels that intersect other labels
			for (int i = labels.Count - 1; i > 0; i--)
				if (labels[i].CompareTo(labels[i - 1]) == 0)
				{
					if (labels[i].Priority > labels[i - 1].Priority)
						labels.RemoveAt(i - 1);
					else
						labels.RemoveAt(i);
				}
		}
		/// <summary>
		/// Thorough label collision detection.
		/// </summary>
		/// <param name="labels"></param>
		public static void ThoroughCollisionDetection(List<SharpMap.Rendering.Label> labels)
		{
			labels.Sort(); // sort labels by intersectiontests of labelbox
			//remove labels that intersect other labels
			for (int i = labels.Count - 1; i > 0; i--)
				for (int j = i - 1; j > 0; j--)
					if (labels[i].CompareTo(labels[j]) == 0)
						if (labels[i].Priority >= labels[j].Priority)
						{
							labels.RemoveAt(j);
							i--;
						}
						else
						{
							labels.RemoveAt(i);
							i--;
							break;
						}
		}
		#endregion
	}
}