TextBox 文本框水印文字

     #region TextBox 文本框水印文字

     /// <summary>

     /// 基于.NET 2.0的TextBox工具类

     /// </summary>

     public static class TextBoxToolV2 {

         private const int EM_SETCUEBANNER = 0x1501;

         [DllImport("user32.dll", CharSet = CharSet.Auto)]

         private static extern Int32 SendMessage

          (IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam);

         /// <summary>

         /// 为TextBox设置水印文字

         /// </summary>

         /// <param name="textBox">TextBox</param>

         /// <param name="watermark">水印文字</param>

         public static void SetWatermark(this TextBox textBox, string watermark) {

             SendMessage(textBox.Handle, EM_SETCUEBANNER, , watermark);

         }

         /// <summary>

         /// 清除水印文字

         /// </summary>

         /// <param name="textBox">TextBox</param>

         public static void ClearWatermark(this TextBox textBox) {

             SendMessage(textBox.Handle, EM_SETCUEBANNER, , string.Empty);

         }

     }

     #endregion