关于在AE的TOC控件中拖动图层时TOC闪动的问题

<P>在本版上看到有用VB（或VB.NET)实现的在AE的TOC控件中拖动图层功能，我改成C#（.net2003）的，出现的问题是：在拖动一个图层之后，TOC刷新之后，带来的闪动，让人感觉很不舒服。VB.NET版的哪个，用到了SendMessage(...)这个函数，但在C#里面，这个函数是受保护的，不让访问；那么该如何控制TOC的刷新的，实现象在ARCMAP里面拖动图层一样的功能呢？？请给予指导，谢谢。</P>

<P>在C#中使用SendMessage </P>
<P>主要描述在调用API函数SendMessage时数据类型的转换。 <BR><BR>-------------------------------------------------------------------------------- <BR><BR>SendMessage是一个在user32.dll中声明的API函数，在C#中导入如下： <BR><BR>using System.Runtime.InteropServices; <BR>[DllImport("user32.dll", EntryPoint="SendMessageA")] <BR>public static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam); <BR>本文描述其参数 lParam 的用法，主要是数据类型之间的转化。 <BR><BR>● 一种最简单的处理方式是声明多个SendMessage函数(overload)，用所需的数据类型直接替换IntPtr。例如： <BR><BR>//声明: <BR>[DllImport("user32.dll", EntryPoint="SendMessageA")] <BR>private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, string lParam); <BR>[DllImport("user32.dll", EntryPoint="SendMessageA")] <BR>private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, ref Rectangle lParam); <BR>//调用: <BR>string s = "hello, floodzhu"; <BR>SendMessage(this.textBox1.Handle, WM_SETTEXT, IntPtr.Zero, s); <BR><BR>Rectangle rect = new Rectangle(); <BR>SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, ref rect); <BR>● 对要求返回字符串的类型（out string）可以用 StringBuilder 代替，此时不需要 out/ref。例如： <BR><BR>[DllImport("user32.dll", EntryPoint="SendMessageA")] <BR>private static extern int SendMessage (IntPtr hwnd, int wMsg, int wParam, StringBuilder lParam); <BR>private void button1_Click(object sender, System.EventArgs e) <BR>{ <BR>const int buffer_size = 1024; <BR>StringBuilder buffer = new StringBuilder(buffer_size); <BR>SendMessage(this.textBox1.Handle, WM_GETTEXT, buffer_size, buffer); <BR>//MessageBox.Show(buffer.ToString()); <BR>} <BR>● 如果想用 InPtr 类型统一处理的话，可以借助于 Marshal 或者 GCHandle 的相关方法。例如： <BR><BR>[DllImport("user32.dll", EntryPoint="SendMessageA")] <BR>private static extern int SendMessage (IntPtr hwnd, int wMsg, IntPtr wParam, IntPtr lParam); <BR><BR>private void button2_Click(object sender, System.EventArgs e) <BR>{ <BR>Rectangle rect = new Rectangle(); <BR>IntPtr buffer = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Rectangle))); <BR>Marshal.StructureToPtr(rect, buffer ,true); <BR><BR>SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, buffer); <BR><BR>rect = (Rectangle)Marshal.PtrToStructure(buffer, typeof(Rectangle)); <BR><BR>Marshal.FreeHGlobal(buffer); <BR>} <BR>或者 <BR><BR>private void button2_Click(object sender, System.EventArgs e) <BR>{ <BR>Rectangle rect = new Rectangle(); <BR>GCHandle gch = GCHandle.Alloc(rect); <BR><BR>SendMessage(this.richTextBox1.Handle, EM_GETRECT, (IntPtr)0, (IntPtr)gch); <BR>rect = (Rectangle)Marshal.PtrToStructure((IntPtr)gch, typeof(Rectangle)); <BR><BR>gch.Free(); <BR>} <BR></P>