csharp: winform using Microsoft.Ink(Tablet PC API) create Signature image

/*
下載：
//Microsoft Windows XP Tablet PC Edition 2005 Recognizer Pack http://www.microsoft.com/zh-cn/download/details.aspx?id=1601
//Microsoft Windows XP Tablet PC Edition Software Development Kit 1.7  http://www.microsoft.com/en-us/download/details.aspx?id=20039
 * Microsoft Speech Platform - Software Development Kit (SDK) (Version 11) http://www.microsoft.com/en-us/download/details.aspx?id=27226
 * Microsoft SDKs http://msdn.microsoft.com/en-us/dd299405.aspx
 *Microsoft.Ink 命名空间  http://msdn.microsoft.com/zh-cn/library/microsoft.ink%28v=vs.90%29.aspx
 * 
 *  安裝的文件在：//Program Files\Microsoft Tablet PC Platform SDK\Include\Microsoft.Ink.dll
 *  在Windows XP sp3 環境下測試
 */

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using Microsoft.Ink; //引用：Micosoft Tablet PC





namespace ChineseCalenderGeovinDu
{
    /// <summary>
    /// 20120914
    /// 塗聚文
    /// 捷為工作室
    /// 締友計算機信息技術有限公司
    /// </summary>
    public partial class TabletPCForm : Form
    {

        InkOverlay inkOverlay;
        InkPicture InkPicture1 = new InkPicture();

        /// <summary>
        /// 
        /// </summary>
        public TabletPCForm()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void TabletPCForm_Load(object sender, EventArgs e)
        {
            inkOverlay = new InkOverlay();
            inkOverlay.Handle = this.pictureBox1.Handle;// this.Handle;//整個窗體
            inkOverlay.Enabled = true;

        }
       
        /// <summary>
        /// 保存圖片
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonSave_Click(object sender, EventArgs e)
        {
            SaveFileDialog sfd = new SaveFileDialog();
            sfd.Filter = "GIF IMAGES(*.gif)|*.gif";
            if (sfd.ShowDialog() == DialogResult.OK)
            {
                txtpath.Text = sfd.FileName;
                FileStream gifFile;
                byte[] fortifiedGif = null;
                // open the file for writing
                gifFile = File.OpenWrite(txtpath.Text);
                // Generate the fortified GIF represenation of the ink
                fortifiedGif = inkOverlay.Ink.Save(PersistenceFormat.Gif);
                // Write and close the gif file
                gifFile.Write(fortifiedGif, 0, fortifiedGif.Length);
                gifFile.Close();
                this.pictureBox2.Image = Image.FromFile(sfd.FileName);
            }
        }

       
        /// <summary>
        /// 清除
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonClear_Click(object sender, EventArgs e)
        {
            inkOverlay.Enabled = false;
            inkOverlay.Ink.DeleteStrokes();
            this.pictureBox1.Invalidate() ;
            this.pictureBox2.Invalidate();
            inkOverlay.Enabled = true;
        }










    }

}