/// <summary>
/// 查找直达路线。
/// </summary>
/// <param name="startNode">开始节点。</param>
/// <param name="endNode">结束节点。</param>
/// <returns>乘车路线。</returns>
private MetroPath FindDirectPath(MetroNode startNode, MetroNode endNode)
{
MetroPath path = new MetroPath();
var startLines = startNode.Links.Select(c => c.Line).Distinct().ToList();
var endLines = endNode.Links.Select(c => c.Line).Distinct().ToList();
var lines = startLines.Where(c => endLines.Contains(c)).ToList();
if (lines.Count == 0)
{
return(path);
}
//查找直达路线
List <MetroPath> pathList = new List <MetroPath>();
foreach (var line in lines)
{
pathList.AddRange(FindShortestPaths(startNode, endNode, line));
}
//挑选最短路线
return(GetShortestPath(pathList));
}
/// <summary>
/// 合并路线。
/// </summary>
/// <exception cref="ArgumentNullException">如果path为空引用，则跑出该异常。</exception>
public MetroPath Merge(MetroPath path)
{
if (path == null)
{
throw new ArgumentNullException("path");
}
MetroPath newPath = new MetroPath();
newPath.Links.AddRange(this.Links);
newPath.Links.AddRange(path.Links);
return(newPath);
}
/// <summary>
/// 最佳一条新的Link，并返回一条新的路线。
/// </summary>
/// <exception cref="ArgumentNullException">如果link为空引用，则跑出该异常。</exception>
public MetroPath Append(MetroLink link)
{
if (link == null)
{
throw new ArgumentNullException("link");
}
MetroPath newPath = new MetroPath();
newPath.Links.AddRange(this.Links);
newPath.Links.Add(link);
return(newPath);
}
/// <summary>
/// 从指定的路线列表中挑选一个最短的路线。
/// </summary>
/// <param name="pathList"></param>
/// <returns></returns>
private MetroPath GetShortestPath(List <MetroPath> pathList)
{
MetroPath minPath = new MetroPath();
int minLength = int.MaxValue;
foreach (var item in pathList)
{
if (item.Links.Count < minLength)
{
minLength = item.Links.Count;
minPath = item;
}
}
return(minPath);
}
/// <summary>
/// 查找乘车路线。
/// </summary>
/// <param name="startNodeName">起点的名称。</param>
/// <param name="endNodeName">终点的名称。</param>
public void FindPath(string startNodeName, string endNodeName)
{
if (!this.Graph.Nodes.Contains(startNodeName))
{
return;
}
if (!this.Graph.Nodes.Contains(endNodeName))
{
return;
}
this.StartNode = this.Graph.Nodes[startNodeName];
this.EndNode = this.Graph.Nodes[endNodeName];
this.CurPath = FindPath(this.StartNode, this.EndNode);
Invalidate();
}
/// <summary>
/// 重写OnMouseUp方法。
/// </summary>
/// <param name="e"></param>
protected override void OnMouseUp(MouseEventArgs e)
{
//选择起点或终点
var node = GetNodeAt(e.Location);
if (node != null && node.Name != "1" && node.Name != "2" && node.Name != "3")
{
if (this.StartNode == null)
{
this.StartNode = node;
}
else
{
this.EndNode = node;
//查找乘车线路
Cursor.Current = Cursors.WaitCursor;
try
{
m_curPath = FindPath(this.StartNode, this.EndNode);
}
finally
{
Cursor.Current = Cursors.Default;
}
}
}
else if (Distance(e.Location, m_mouseDownPoint) < 3)//是否发生拖拽
{
this.StartNode = this.EndNode = null;
this.CurPath.Links.Clear();
if (CurPath.Links.Count > 0)
{
this.BackColor = Color.White;
}
else
{
this.BackColor = Color.WhiteSmoke;
}
}
Invalidate();
}
/// <summary>
/// 查找指定两个节点之间的最短路径。
/// </summary>
/// <param name="startNode">开始节点。</param>
/// <param name="endNode">结束节点。</param>
/// <param name="line">目标线路（为null表示不限制线路）。</param>
/// <returns>乘车路线列表。</returns>
private List <MetroPath> FindShortestPaths(MetroNode startNode, MetroNode endNode, MetroLine line)
{
List <MetroPath> pathtList = new List <MetroPath>();
if (startNode == endNode)
{
return(pathtList);
}
//路径队列，用于遍历路径
Queue <MetroPath> pathQueue = new Queue <MetroPath>();
pathQueue.Enqueue(new MetroPath());
while (pathQueue.Count > 0)
{
var path = pathQueue.Dequeue();
//如果已经超过最短路径，则直接返回
if (pathtList.Count > 0 && path.Links.Count > pathtList[0].Links.Count)
{
continue;
}
//路径的最后一个节点
MetroNode prevNode = path.Links.Count > 0 ? path.Links[path.Links.Count - 1].From : null;
MetroNode lastNode = path.Links.Count > 0 ? path.Links[path.Links.Count - 1].To : startNode;
//继续寻找后续节点
//int Gx_min = int.MaxValue;
//int Gx;
foreach (var link in lastNode.Links.Where(c => c.To != prevNode && (line == null || c.Line == line)))
{
/*Gx = Math.Abs(link.To.X - endNode.X) + Math.Abs(link.To.Y - endNode.Y) + 500 * path.Links.Count;
*
* if (Gx < Gx_min)
* Gx_min = Gx;
* else
* continue;*/
if (link.Weight == 2)
{
continue;
}
if (link.To == endNode)
{
MetroPath newPath = path.Append(link);
if (pathtList.Count == 0 || newPath.Links.Count == pathtList[0].Links.Count)
{//找到一条路径
pathtList.Add(newPath);
}
else if (newPath.Links.Count < pathtList[0].Links.Count)
{//找到一条更短的路径
pathtList.Clear();
pathtList.Add(newPath);
}
else
{
break; //更长的路径没有意义
}
}
else if (!path.ContainsNode(link.To))
{
pathQueue.Enqueue(path.Append(link));
}
link.Weight = 2;
}
}
return(pathtList);
}
/// <summary>
/// 查找乘车路线。
/// </summary>
/// <param name="startNode">起点。</param>
/// <param name="endNode">终点。</param>
/// <returns>乘车路线。</returns>
public MetroPath FindPath(MetroNode startNode, MetroNode endNode)
{
MetroPath path = new MetroPath();
if (startNode == null || endNode == null)
{
return(path);
}
if (startNode == endNode)
{
return(path);
}
foreach (var item in this.Graph.Nodes)
{
foreach (var link in item.Links)
{
link.Weight = 3;
}
}
//如果起点和终点拥有共同线路，则查找直达路线
path = FindDirectPath(startNode, endNode);
if (path.Links.Count > 0)
{
return(path);
}
//如果起点和终点拥有一个共同的换乘站点，则查找一次换乘路线
//path = FindOneTransferPath(startNode, endNode);
//if (path.Links.Count > 0) return path;
//查找路径最短的乘车路线
var pathList = FindShortestPaths(startNode, endNode, null);
//查找换乘次数最少的一条路线
int minTransfers = int.MaxValue;
foreach (var item in pathList)
{
var curTransfers = item.Transfers;
if (curTransfers < minTransfers)
{
minTransfers = curTransfers;
path = item;
}
}
if (CurPath.Links.Count > 0)
{
this.BackColor = Color.White;
}
else
{
this.BackColor = Color.WhiteSmoke;
}
return(path);
}