使用者控制項自訂設計器

如果不知道什麼是使用者控制項請搜尋。如果不知道組件和控制項的區別，請到論壇問。

最近在做一些組件的時候，希望能夠像Tabcontrol那樣的AddTab，RemoveTab的動作。

我個人覺得是設計自動化很重要的技術，所以我一直在尋找。很可惜的是，找到的多是輔助修改屬性的東西，個人覺得沒什麼實際意義。動詞對於開發組件和控制項至關重要。

下面的例子是一個控制項的，帶有動詞的，很好的例子。組件的相似，要簡單些。讀者閱讀前需要瞭解Desiger的相關知識。不過複製代碼，可以看看效果。我在VS2003上做的。

 using System;
//using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.ComponentModel;
using System.Windows.Forms.Design;
using System.ComponentModel.Design;

namespace WindowsFormsApplication1
{
 [Designer(typeof(DemoControlDesigner))]
 public class DemoControl : Control
 {
 }

 internal class DemoControlDesigner : ControlDesigner
 {
  public override DesignerVerbCollection Verbs
  {
   get
   {
    DesignerVerbCollection verbs = new DesignerVerbCollection();
    verbs.Add(new DesignerVerb("Add a new Button", new EventHandler(AddNewButton)));
    verbs.Add(new DesignerVerb("Remove an existed Button", new EventHandler(RemoveExistedButton)));
    return verbs;
   }
  }

  private void AddNewButton(object sender, EventArgs e)
  {
   Control ctrl = this.Control;
   if (ctrl != null && ctrl.Parent != null)
   {
    IDesignerHost host = this.GetService(typeof(IDesignerHost)) as IDesignerHost;
    if (host != null)
    {
     DesignerTransaction trans = host.CreateTransaction("Add a new button");
     try
     {
      Control button = host.CreateComponent(typeof(Button)) as Control;
      // other control initialization, must use ProeprtyDescriptor to set properties!
      // Add to parent control's control collection.
      PropertyDescriptor pd = TypeDescriptor.GetProperties(ctrl.Parent)["Controls"];
      if (pd != null)
      {
       Control.ControlCollection cc = pd.GetValue(ctrl.Parent) as Control.ControlCollection;
       if (cc != null)
       {
        cc.Add(button);
        trans.Commit();
        return;
       }
      }
      trans.Cancel();
     }
     catch
     {
      trans.Cancel();
     }
    }
   }
  }

  private void RemoveExistedButton(object sender, EventArgs e)
  {
   Control ctrl = this.Control;
   if (ctrl != null && ctrl.Parent != null)
   {
    IDesignerHost host = this.GetService(typeof(IDesignerHost)) as IDesignerHost;
    if (host != null)
    {
     DesignerTransaction trans = host.CreateTransaction("Remove an existed Button");
     try
     {
      PropertyDescriptor pd = TypeDescriptor.GetProperties(ctrl.Parent)["Controls"];
      if (pd != null)
      {
       Control.ControlCollection cc = pd.GetValue(ctrl.Parent) as Control.ControlCollection;
       if (cc != null)
       {
        for (int i = cc.Count - 1; i >= 0; i--)
        {
         if(cc[i] is Button)
         {
          cc.RemoveAt(i);
          trans.Commit();
          return;
         }
        }
       }
      }
      trans.Cancel();
     }
     catch(Exception ex)
     {
      MessageBox.Show(ex.ToString());
      trans.Cancel();
     }
    }
   }
  }
 }
}