using?System;
using?System.Collections.Generic;
using?System.Text;
using?System.Collections;
using?System.Drawing;

namespace?MapControlApplication2
{
????class?Douglasclass
????{
????????///?

????????///?使用“道格拉斯—普克”算法減少點的數量
????????///?

????????///?需要減少的點
????????///?偏差
????????///?得到減少過后的結果點
????????public?List?DouglasPeuckerReduction（List?Points?Double?Tolerance）
????????{
????????????//if?（Tolerance?==?0）?return?Points;
????????????if?（Points?==?null?||?Points.Count?????????????????return?Points;
????????????Int32?firstPoint?=?0;
????????????Int32?lastPoint?=?Points.Count?-?1;
????????????List?pointIndexsToKeep?=?new?List（）;
????????????//把第一個點和最后一個點的序號加入要保存的序號?對于數據中第一個和最后一個點重合的情況不壓縮
????????????pointIndexsToKeep.Add（firstPoint）;
????????????pointIndexsToKeep.Add（lastPoint）;
????????????//第一個點和最后一個點不能為同一個點
????????????while?（Points[firstPoint].Equals（Points[lastPoint]））
????????????{
????????????????lastPoint--;
????????????}
????????????DouglasPeuckerReduction（Points?firstPoint?lastPoint?Tolerance?ref?pointIndexsToKeep）;//道格拉斯-普克壓縮
????????????List?returnPoints?=?new?List（）;
????????????pointIndexsToKeep.Sort（）;//對保留下來的序號進行排序
????????????foreach?（Int32?index?in?pointIndexsToKeep）
????????????{
????????????????returnPoints.Add（Points[index]）;//將對應序號的點加入
????????????}
????????????return?returnPoints;//返回壓縮后的點
????????}
????????

????????///?

????????///?道格拉斯-普克壓縮
????????///?

????????///?要處理的點
????????///?第一個點
????????///?最后一個點
????????///?偏差
????????///?要保留點的索引號
????????private?static?void?DouglasPeuckerReduction（List?points?Int32?firstPoint?Int32?lastPoint?Double?tolerance?ref?List?pointIndexsToKeep）
????????{
????????????Double?maxDistance?=?0;
????????????Int32?indexFarthest?=?0;
????????????for?（Int32?inde