为什么自定义控制任务窗格不更新其属性？

Question

我设计了一个可以在运行时扩展或折叠窗体的自定义面板。

当我从自定义设计的任务改变其高度时，它不会更新它。

我的控制类的代码：

taskpanedesign类的

using System; 
using System.Windows.Forms; 
using System.ComponentModel; 
using System.ComponentModel.Design; 
using System.Windows.Forms.Design; 

[Designer(typeof(MyControlDesigner))] 
public partial class ExpandCollapsePanel : UserControl 
    {  
     private bool flag = false; 
     private Size size; 
     public int usrVerticalSize; 

     public ExpandCollapsePanel() 
     { 
      InitializeComponent(); 

     }  
     [DefaultValueAttribute(true)] 
     public int SetVerticalSize 
     { 
      get 
      { 
       return usrVerticalSize; 
      } 
      set 
      { 
       usrVerticalSize = value; 
      } 
     } 

代码：

namespace ExpandCollapseFormLibrary 
{ 
    class CustomDialogue : ControlDesigner 
    { 
     private DesignerActionListCollection actionLists; 
     public override DesignerActionListCollection ActionLists 
     { 
      get 
      { 
       if (actionLists == null) 
       { 
        actionLists = new DesignerActionListCollection(); 
        actionLists.Add(new MyActionListItem(this)); 
       } 
       return actionLists; 
      } 
     } 
    } 
    internal class MyActionListItem : DesignerActionList 
    { 
     public MyActionListItem(ControlDesigner owner) : base(owner.Component) 
     { 
     } 
     public override DesignerActionItemCollection GetSortedActionItems() 
     { 
      var items = new DesignerActionItemCollection(); 
      //items.Add(new DesignerActionTextItem("Hello world", "Misc")); 
      items.Add(new DesignerActionPropertyItem("Checked", "Vertical Drop Down Size")); 
      return items; 
     } 

     public int Checked 
     { 
      get { return ((ExpandCollapsePanel)base.Component).SetVerticalSize; } 
      set { ((ExpandCollapsePanel)base.Component).SetVerticalSize = value; } 
     } 

    }  
} 

当我改变值在Form1（其中拖动和删除）设计类永远保存。

Answer 1

您的自定义窗格的SetVerticalSize属性值确实发生了变化，但问题在于设计器主机根本不知道它。为了通知设计者主机您的自定义面板改变了你应该实现这样的事情（我建议你了解更多详情阅读IComponentChangeService MSDN article）：

int usrVerticalSize; 
    [DefaultValue(true)] 
    public int SetVerticalSize { 
     get { return usrVerticalSize; } 
     set { 
      FireChanging(); //changing notification 
      try { 
       usrVerticalSize = value; 
      } 
      finally { FireChanged(); } //changed notification 
     } 
    } 
    void FireChanging() { 
     IComponentChangeService service = GetComponentChangeService(); 
     if(service != null) 
      service.OnComponentChanging(this, null); 
    } 
    void FireChanged() { 
     IComponentChangeService service = GetComponentChangeService(); 
     if(service != null) 
      service.OnComponentChanged(this, null, null, null); 
    } 
    IComponentChangeService GetComponentChangeService() { 
     return GetService(typeof(IComponentChangeService)) as IComponentChangeService; 
    }