一起谈.NET技术，Silverlight中使用递归构造关系图

　　这两天遇到一个问题，项目中需要在silverlight中使用连接图的方式来显示任务之间的关系，总体有父子和平行两种，昨天在改同事的代码，一直出问题，索性晚上写了一下实现方法。

　　需求

　　有一个List对象中存了若干个Task，这些Task对象通过ParentID属性进行关联，现在要求将这个List中的任务使用图的方式形成如父子关系和平行关系的图示例如下图：

　　实现方法思考

　　刚开始接到这个任务我就想着递归应该可以搞定了，但是仔细考虑才发现每个任务的子任务需要在一定区域内才行，需要计算子级和子级之间的距离，如果使用递归，例如上图的元素“12”的位置就没有办法很好确定了。

　　我决定将途中的节点抽象为一个类，这个类至少应该含有上边界top,左边届left及节点的名称等属性，然后从这个List对象中构造出每个节点的属性。

　　实现步骤

　　1，首先我们为图模拟一个数据源，注意其中的任务是通过ParentID关联的。

private static List<Task> listTask; 
        public MainPage() 
        { 
            InitializeComponent(); 
            listTask = new List<Task>(); 
            listTask.Add(new Task() { ID = 1, ParentID = 0, Name = "1" }); 
            listTask.Add(new Task() { ID = 2, ParentID = 1, Name = "11" }); 
            listTask.Add(new Task() { ID = 3, ParentID = 1, Name = "12" }); 
            listTask.Add(new Task() { ID = 4, ParentID = 2, Name = "21" }); 
            listTask.Add(new Task() { ID = 5, ParentID = 2, Name = "22" }); 
            listTask.Add(new Task() { ID = 6, ParentID = 3, Name = "31" }); 
            listTask.Add(new Task() { ID = 7, ParentID = 3, Name = "32" }); 
            listTask.Add(new Task() { ID = 8, ParentID = 3, Name = "33" }); 
            listTask.Add(new Task() { ID = 9, ParentID = 4, Name = "42" }); 
            listTask.Add(new Task() { ID = 10, ParentID =4, Name = "42" }); 
            listTask.Add(new Task() { ID = 11, ParentID =3, Name = "34" }); 
            listTask.Add(new Task() { ID = 12, ParentID = 5, Name = "51" }); 
            listTask.Add(new Task() { ID = 13, ParentID = 8, Name = "81" }); 
            this.Loaded += new RoutedEventHandler(MainPage_Loaded); 
        }

　　2，然后我们为要生成的图中节点构造一个类。

class TaskPro 
        { 
            public Task task { set; get; } 
            public double top { set; get; } 
            public double left { set; get; } 
            public int index { set; get; }//这是为了找到节点在某层的位置来计算left 
        }

　　3，使用递归将List中的数据做初步整理，存入一个List<TaskPro>中，此时节点对象将具备top属性，上边距搞定。

void AddMethod(Task task) 
        { 
            if (task.ParentID == 0) 
            { 
                listOfTaskPro.Add(new TaskPro() { task = task, top = 0, index = 0, left = 0  }); 
            } 
            else 
            { 
                var t=listTask.Where(m=>m.ID==task.ParentID).FirstOrDefault(); 
                var tpro=listOfTaskPro.Where(m=>m.task.ID==t.ID).FirstOrDefault(); 
                listOfTaskPro.Add(new TaskPro() { task=task, index=0, top=tpro.top+50, left=0 }); 
            } 
            foreach (Task t in listTask.Where(m=>m.ParentID==task.ID).ToList()) 
            { 
                AddMethod(t);          
            } 
        }

　　4，我们需要算出节点对象的左边距，在第3步中我没能找到方法，于是想到利用每一级的元素个数来计算每个节点的位置，然后使用每一级的平均节点距离*节点的索引便可得到left。

//构造各层及数量 
            foreach (TaskPro t in listOfTaskPro) 
            { 
                bool IsExist = false; 
                foreach (TaskCount tc in listTopAndTasks) 
                { 
                    IsExist = tc.Top==t.top?true:false; 
                } 
                if (!IsExist) 
                { 
                    listTopAndTasks.Add(new TaskCount() { Top = t.top, Tasks = new List<Task>() }); 
                } 
                var topAndTasks = listTopAndTasks.Where(m => m.Top == t.top).FirstOrDefault(); 
                topAndTasks.Tasks.Add(t.task); 
            } 
            //构造index 
            foreach (TaskPro t in listOfTaskPro) 
            { 
                for (int i = 0; i < listTopAndTasks.Count; i++) 
                { 
                    for (int j = 0; j < listTopAndTasks[i].Tasks.Count; j++) 
                    { 
                        if (listTopAndTasks[i].Tasks[j].ID == t.task.ID) 
                        { 
                            t.index = j + 1; 
                        } 
                    } 
                } 
            } 
            //构造left 
            for (int i = 0; i < listOfTaskPro.Count; i++) 
            { 
                if (listOfTaskPro[i].task.ParentID == 0) 
                { 
                    listOfTaskPro[i].left = this.canvas1.Width / 2; 
                } 
                else 
                { 
                    var childCount = listOfTaskPro.Where(m => m.task.ParentID == listOfTaskPro[i].task.ParentID).Count(); 
                    var parentLeft = listOfTaskPro.Where(m => m.task.ID == listOfTaskPro[i].task.ParentID).FirstOrDefault().left; 
                    var perLength = parentLeft * 1.5 / (childCount + 1); 
                    listOfTaskPro[i].left = listOfTaskPro[i].index * perLength; 
                } 
            }

　　5，至此，节点对象已经具备了left,top属性，我们只需要找到每个节点的父节点即可将两个几点的坐标确定，进而进行划线的操作了。

foreach (TaskPro t in listOfTaskPro) 
            { 
                AddBtn(t.task.Name, t.left, t.top); 
                if (t.task.ParentID != 0) 
                { 
                    TaskPro tp = listOfTaskPro.Where(m => m.task.ID == t.task.ParentID).FirstOrDefault(); 
                    AddLine(tp.left + buttonWidth / 2, tp.top + buttonHeight, t.left + buttonWidth / 2, t.top); 
                } 
            }

　　6，添加按钮及划线的方法。

#region 添加按钮及线条 
        double buttonHeight = 20; 
        double buttonWidth = 50; 

        void AddBtn(string content, double left, double top) 
        { 
            Button btn = new Button(); 
            btn.Content = content; 
            btn.Width = buttonWidth; 
            btn.Height = buttonHeight; 
            this.canvas1.Children.Add(btn); 
            Canvas.SetLeft(btn, left); 
            Canvas.SetTop(btn, top); 
        } 

//画线方法，只需要有起始亮点的坐标即可

        void AddLine(double startLeft, double startTop, double endLeft, double endTop) 
        { 
            Path p = new Path(); 
            LineGeometry geometry = new LineGeometry(); 
            SolidColorBrush brush = new SolidColorBrush(); 
            brush.Color = Colors.Black; 
            geometry.StartPoint = new Point(startLeft, startTop); 
            geometry.EndPoint = new Point(endLeft, endTop); 
            p.Data = geometry; 
            p.Stroke = brush; 
            p.StrokeThickness = 1; 
            canvas1.Children.Add(p); 
        } 
        #endregion

　　运行一下，如上图。之前没有使用递归的方法是只有这样的。

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Net; 
using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Documents; 
using System.Windows.Input; 
using System.Windows.Media; 
using System.Windows.Media.Animation; 
using System.Windows.Shapes; 

namespace SilverlightApplication2 
{ 
    public class Task 
    { 
        public int ID { set; get; } 
        public int ParentID { set; get; } 
        public string Name { set; get; } 
    } 
    public partial class MainPage : UserControl 
    { 
        private static List<Task> listTask; 
        public MainPage() 
        { 
            InitializeComponent(); 
            listTask = new List<Task>(); 
            listTask.Add(new Task() { ID = 1, ParentID = 0, Name = "1" }); 
            listTask.Add(new Task() { ID = 2, ParentID = 1, Name = "11" }); 
            listTask.Add(new Task() { ID = 3, ParentID = 1, Name = "12" }); 
            listTask.Add(new Task() { ID = 4, ParentID = 2, Name = "21" }); 
            listTask.Add(new Task() { ID = 5, ParentID = 2, Name = "22" }); 
            listTask.Add(new Task() { ID = 6, ParentID = 3, Name = "31" }); 
            listTask.Add(new Task() { ID = 7, ParentID = 3, Name = "32" }); 
            listTask.Add(new Task() { ID = 8, ParentID = 3, Name = "33" }); 
            listTask.Add(new Task() { ID = 9, ParentID = 4, Name = "42" }); 
            listTask.Add(new Task() { ID = 10, ParentID =4, Name = "42" }); 
            listTask.Add(new Task() { ID = 11, ParentID =3, Name = "34" }); 
            listTask.Add(new Task() { ID = 12, ParentID = 5, Name = "51" }); 
            listTask.Add(new Task() { ID = 13, ParentID = 8, Name = "81" }); 
            this.Loaded += new RoutedEventHandler(MainPage_Loaded); 
        } 
        void MainPage_Loaded(object sender, RoutedEventArgs e) 
        {             
            AddAll();         
        }        
        class TaskPro 
        { 
            public Task task { set; get; } 
            public double top { set; get; } 
            public double left { set; get; } 
            public int index { set; get; } 
        } 
        class TaskCount 
        { 
            public double Top { set; get; } 
            public List<Task> Tasks { set; get; } 
        } 
        static List<TaskPro> listTaskPro = new List<TaskPro>(); 
        static List<TaskCount> listTopAndTasks = new List<TaskCount>(); 
        void AddAll() 
        { 
            foreach(Task t in listTask) 
            { 
                if (t.ParentID == 0) 
                { 
                    listTaskPro.Add(new TaskPro() { task = t, index = 1, left = this.canvas1.Width / 2, top = 0 }); 
                } 
                else 
                { 
                    for(int i=0;i<listTaskPro.Count;i++) 
                    { 
                        if (t.ParentID == listTaskPro[i].task.ID) 
                        { 
                            listTaskPro.Add(new TaskPro() { task = t, top = listTaskPro[i].top + 80, index = 0, left = 0 }); 
                        } 
                    } 
                } 
            } 

            #region 汇总层及层内的元素个数 
            foreach (TaskPro t in listTaskPro) 
            { 
                bool IsExist = false; 
                foreach(TaskCount tc in listTopAndTasks) 
                { 
                    if(tc.Top==t.top) 
                    { 
                        IsExist = true; 
                    } 
                } 
                if(!IsExist) 
                { 
                    listTopAndTasks.Add(new TaskCount() { Top=t.top, Tasks=new List<Task>() }); 
                } 
                var topAndTasks = listTopAndTasks.Where(m=>m.Top==t.top).FirstOrDefault(); 
                topAndTasks.Tasks.Add(t.task);               
            } 
            #endregion 

            foreach (TaskPro t in listTaskPro) 
            { 
                for (int i = 0; i < listTopAndTasks.Count;i++ ) 
                { 
                    for (int j = 0; j < listTopAndTasks[i].Tasks.Count;j++ ) 
                    { 
                        if (listTopAndTasks[i].Tasks[j].ID == t.task.ID) 
                        { 
                            t.index = j + 1; 
                        } 
                    } 
                } 
            } 

            for (int i = 0; i < listTaskPro.Count; i++) 
            { 
                if (listTaskPro[i].task.ParentID == 0) 
                { 
                    listTaskPro[i].left = this.canvas1.Width / 2; 
                } 
                else 
                { 
                    var childCount = listTaskPro.Where(m => m.task.ParentID == listTaskPro[i].task.ParentID).Count(); 
                    var parentLeft = listTaskPro.Where(m => m.task.ID == listTaskPro[i].task.ParentID).FirstOrDefault().left; 
                    var perLength = parentLeft*1.5 / (childCount + 1); 
                    listTaskPro[i].left=listTaskPro[i].index*perLength;                                     
                } 
            } 
            foreach (TaskPro t in listTaskPro) 
            { 
                AddBtn(t.task.Name, t.left, t.top); 
                if(t.task.ParentID!=0) 
                { 
                    TaskPro tp = listTaskPro.Where(m=>m.task.ID==t.task.ParentID).FirstOrDefault(); 
                    AddLine(tp.left+buttonWidth/2, tp.top+buttonHeight, t.left+buttonWidth/2, t.top); 
                } 
            } 
        } 
        double buttonHeight = 20; 
        double buttonWidth = 50; 
        void AddBtn(string content,double left,double top) 
        { 
            Button btn = new Button(); 
            btn.Content = content; 
            btn.Width = buttonWidth; 
            btn.Height = buttonHeight; 
            this.canvas1.Children.Add(btn); 
            Canvas.SetLeft(btn, left); 
            Canvas.SetTop(btn, top); 
        } 

        void AddLine(double startLeft,double startTop,double endLeft,double endTop) 
        { 
            Path p = new Path(); 
            LineGeometry geometry = new LineGeometry(); 
            SolidColorBrush brush = new SolidColorBrush();             

            brush.Color = Colors.Black; 
            geometry.StartPoint = new Point(startLeft, startTop); 
            geometry.EndPoint = new Point(endLeft, endTop); 
            p.Data = geometry; 
            p.Stroke = brush; 
            p.StrokeThickness = 1; 

            canvas1.Children.Add(p); 
        } 
    } 
}