* UITreeView： CheckBoxes增加三态，感谢群友：笑口常开

SunnyUI/Controls/UITreeView.cs

@@ -20,14 +20,18 @@
  * 2020-07-07: V2.2.6 全部重写，增加圆角，CheckBoxes等
  * 2020-08-12: V2.2.7 更新可设置背景色
  * 2021-07-19: V3.0.5 调整了显示CheckBoxes时图片位置
+ * 2021-08-26: V3.0.6 CheckBoxes增加三态，感谢群友：笑口常开 
 ******************************************************************************/
 
 using System;
 using System.Collections;
+using System.Collections.Generic;
 using System.ComponentModel;
+using System.Data;
 using System.Drawing;
 using System.Drawing.Design;
 using System.Drawing.Drawing2D;
+using System.Linq;
 using System.Windows.Forms;
 
 namespace Sunny.UI
@@ -698,12 +702,13 @@ namespace Sunny.UI
             {
                 base.OnDrawNode(e);
 
-                if (e.Node == null) return;
+                if (e.Node == null || Nodes.Count == 0) return;
 
+                try
+                {
                     if (BorderStyle == BorderStyle.Fixed3D) BorderStyle = BorderStyle.FixedSingle;
 
-                if (e.Node == null || e.Node.Bounds.Width <= 0 && e.Node.Bounds.Height <= 0 && e.Node.Bounds.X <= 0 &&
+                    if (e.Node == null || e.Node.Bounds.Width <= 0 && e.Node.Bounds.Height <= 0 && e.Node.Bounds.X <= 0 && e.Node.Bounds.Y <= 0)
-                    e.Node.Bounds.Y <= 0)
                     {
                         e.DrawDefault = true;
                     }
@@ -729,6 +734,8 @@ namespace Sunny.UI
                         }
 
                         var checkboxColor = ForeColor;
+                        if (e.Node != null)
+                        {
                             if (e.Node == SelectedNode)
                             {
                                 e.Graphics.FillRectangle((e.State & TreeNodeStates.Hot) != 0 ? HoverColor : SelectedColor,
@@ -768,12 +775,12 @@ namespace Sunny.UI
                             if (CheckBoxes)
                             {
                                 if (!e.Node.Checked)
-                            using (var pn = new Pen(checkboxColor, 1))
                                 {
-                                e.Graphics.DrawRectangle(pn,
+                                    e.Graphics.DrawRectangle(checkboxColor,
                                         new Rectangle(checkBoxLeft + 2, e.Bounds.Y + (ItemHeight - 12) / 2 - 1, 12, 12));
                                 }
                                 else
+                                {
                                     using (var pn = new Pen(checkboxColor, 2))
                                     {
                                         var pt1 = new Point(checkBoxLeft + 2 + 2, e.Bounds.Y + (ItemHeight - 12) / 2 - 1 + 5);
@@ -790,10 +797,27 @@ namespace Sunny.UI
                                     }
                                 }
 
+                                if (!DicNodeStatus.Keys.Contains(e.Node.GetHashCode()))
+                                {
+                                    DicNodeStatus.Add(e.Node.GetHashCode(), false);
+                                }
+
+                                if (DicNodeStatus[e.Node.GetHashCode()])
+                                {
+                                    var location = e.Node.Bounds.Location;
+                                    location.Offset(-29, 10);
+                                    var size = new Size(7, 7);
+                                    e.Graphics.FillRectangle(checkboxColor, new Rectangle(location, size)); //这里绘制的是正方形
+
+                                }
+                            }
+                        }
+
                         var lineY = e.Bounds.Y + e.Node.Bounds.Height / 2 - 1;
                         var lineX = 3 + e.Node.Level * Indent + 9;
 
                         if (ShowLinesEx)
+                        {
                             try
                             {
                                 //绘制虚线
@@ -812,16 +836,21 @@ namespace Sunny.UI
                                     {
                                         lineX -= Indent;
 
+                                        if (pNode != null && Nodes.Count > 0)
+                                        {
                                             if (pNode.NextNode != null)
                                                 e.Graphics.DrawLine(pn, lineX, lineY, lineX, e.Node.Bounds.Top);
 
                                             if (pNode.NextNode != null)
                                                 e.Graphics.DrawLine(pn, lineX, lineY, lineX, e.Node.Bounds.Bottom);
+                                        }
 
                                         pNode = pNode.Parent;
                                     }
                                 }
                                 else
+                                {
+                                    if (e.Node != null && Nodes.Count > 0)
                                     {
                                         if (e.Node.PrevNode != null)
                                             e.Graphics.DrawLine(pn, lineX, lineY, lineX, e.Node.Bounds.Top);
@@ -829,6 +858,7 @@ namespace Sunny.UI
                                         if (e.Node.NextNode != null)
                                             e.Graphics.DrawLine(pn, lineX, lineY, lineX, e.Node.Bounds.Bottom);
                                     }
+                                }
 
                                 pn.Dispose();
                             }
@@ -836,6 +866,7 @@ namespace Sunny.UI
                             {
                                 Console.WriteLine(exception);
                             }
+                        }
 
                         lineX = 3 + e.Node.Level * Indent + 9;
                         //绘制左侧+号
@@ -849,6 +880,11 @@ namespace Sunny.UI
                         }
                     }
                 }
+                catch (Exception ex)
+                {
+                    Console.WriteLine(ex.Message);
+                }
+            }
 
             private bool TreeNodeSelected(DrawTreeNodeEventArgs e)
             {
@@ -867,6 +903,74 @@ namespace Sunny.UI
 
                 base.WndProc(ref m);
             }
+
+            private Dictionary<int, bool> DicNodeStatus = new Dictionary<int, bool>();
+
+            protected override void OnAfterCheck(TreeViewEventArgs e)
+            {
+
+                base.OnAfterCheck(e);
+                if (e.Action == TreeViewAction.ByMouse) //鼠标点击
+                {
+                    DicNodeStatus[e.Node.GetHashCode()] = false;
+
+                    SetChildNodeCheckedState(e.Node, e.Node.Checked);
+                    if (e.Node.Parent != null)
+                    {
+                        SetParentNodeCheckedState(e.Node);
+                    }
+
+                }
+
+            }
+
+            private void SetParentNodeCheckedState(TreeNode currNode)
+            {
+                TreeNode parentNode = currNode.Parent; //获得当前节点的父节点
+
+                var count = parentNode.Nodes.Cast<TreeNode>().Where(n => n.Checked).ToList().Count;
+
+                parentNode.Checked = count == parentNode.Nodes.Count;
+
+                var half = parentNode.Nodes.Cast<TreeNode>().Where(n => DicNodeStatus[n.GetHashCode()]).ToList().Count;
+
+                if ((count > 0 && count < parentNode.Nodes.Count) || half > 0)
+                {
+                    DicNodeStatus[parentNode.GetHashCode()] = true;
+                }
+                else
+                {
+                    DicNodeStatus[parentNode.GetHashCode()] = false;
+                }
+
+
+                var g = CreateGraphics();
+                OnDrawNode(new DrawTreeNodeEventArgs(g, parentNode,
+                    new Rectangle(0, parentNode.Bounds.Y, Width, parentNode.Bounds.Height), TreeNodeStates.Hot));
+                g.Dispose();
+
+
+                if (parentNode.Parent != null) //如果父节点之上还有父节点
+                {
+                    SetParentNodeCheckedState(parentNode); //递归调用
+                }
+            }
+
+
+            //选中节点之后，选中节点的所有子节点
+            private void SetChildNodeCheckedState(TreeNode currNode, bool state)
+            {
+                TreeNodeCollection nodes = currNode.Nodes; //获取所有子节点
+                if (nodes.Count > 0) //存在子节点
+                {
+                    foreach (TreeNode tn in nodes)
+                    {
+                        DicNodeStatus[tn.GetHashCode()] = false;
+                        tn.Checked = state;
+                        SetChildNodeCheckedState(tn, state);//递归调用子节点的子节点
+                    }
+                }
+            }
         }
     }
 }

SunnyUI/Pages/UIPage.cs

@@ -21,7 +21,7 @@
  * 2021-06-20: V3.0.4 增加标题行，替代UITitlePage
  * 2021-07-18: V3.0.5 修复OnLoad在加载时重复加载两次的问题，增加Final函数，每次页面切换，退出页面都会执行
  * 2021-08-17: V3.0.6 增加TitleFont属性
- * 2021-08-24: V3.0.3 修复OnLoad在加载时重复加载两次的问题
+ * 2021-08-24: V3.0.6 修复OnLoad在加载时重复加载两次的问题
 ******************************************************************************/
 
 using System;