怎么会这样？？？

Question

从网上下了两个用摄像头进行拍照的实例，出现了这种情况：当程序第一次运行时没有问题，摄像头启动，然后进行拍照。但是当进行第二三等以后几次运行时，就会出现问题，会弹出一个窗口：点击“确定”、“应用”都没有效果。请问这是什么原因造成的，应该怎样修正？？？代码如下：
using System;
using System.Runtime.InteropServices;
using System.Drawing.Imaging;
using System.Windows.Forms;
using System.Drawing;namespace YHhotel.YHhotelWindows
{
    /// <summary>
    /// Class1 的摘要说明。
    /// </summary>
    public class video
    {
        //5个传入参数
        private IntPtr myHand;
        private int myWidth;
        private short myHeight;
        private int myLeft;
        private int myTop;
        //调用avicap32.dll 
        public struct videohdr_tag
        {
            public byte[] lpData;
            public int dwBufferLength;
            public int dwBytesUsed;
            public int dwTimeCaptured;
            public int dwUser;
            public int dwFlags;
            public int[] dwReserved;        }
        [DllImport("avicap32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern int capCreateCaptureWindowA([MarshalAs(UnmanagedType.VBByRefStr)]   ref   string lpszWindowName, int dwStyle, int x, int y, int nWidth, short nHeight, int hWndParent, int nID);
        [DllImport("avicap32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern bool capGetDriverDescriptionA(short wDriver, [MarshalAs(UnmanagedType.VBByRefStr)]   ref   string lpszName, int cbName, [MarshalAs(UnmanagedType.VBByRefStr)]   ref   string lpszVer, int cbVer);
        [DllImport("user32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern bool DestroyWindow(int hndw);
        [DllImport("user32", EntryPoint = "SendMessageA", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern int SendMessage(int hwnd, int wMsg, int wParam, [MarshalAs(UnmanagedType.AsAny)]   object lParam);
        [DllImport("user32", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern int SetWindowPos(int hwnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags);
        [DllImport("vfw32.dll")]
        public static extern string capVideoStreamCallback(int hwnd, videohdr_tag videohdr_tag);
        [DllImport("vicap32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
        public static extern bool capSetCallbackOnFrame(int hwnd, string s);
        //自定义参数：
        private int hHwnd;
        //构造函数
        public video(IntPtr myPtr, int left, int top, int width, short height)
        {
            myHand = myPtr;
            myLeft = left;
            myTop = top;
            myWidth = width;
            myHeight = height;
            //
            // TODO: 在此处添加构造函数逻辑
            //
        }        //打开视频：
        public void opVideo()
        {
            int intDevice = 0;
            string refDevice = intDevice.ToString();
            hHwnd = capCreateCaptureWindowA(ref   refDevice, 1342177280, 0, 0, 640, 480, myHand.ToInt32(), 0);
            if (SendMessage(hHwnd, 0x40a, intDevice, 0) > 0)
            {
                SendMessage(this.hHwnd, 0x435, -1, 0);
                SendMessage(this.hHwnd, 0x434, 0x42, 0);
                SendMessage(this.hHwnd, 0x432, -1, 0);
                SetWindowPos(this.hHwnd, 1, 0, 0, myWidth, Convert.ToInt32(myHeight), 6);
            }
            else
            {
                DestroyWindow(this.hHwnd);
            }
        }
        //停止视频
        public void CloVideo()
        {
            SendMessage(this.hHwnd, 0x40b, 0, 0);
            DestroyWindow(this.hHwnd);
        }
        //捕获视频
        public Image CatchVideo()
        {
            SendMessage(this.hHwnd, 0x41e, 0, 0);
            IDataObject obj1 = Clipboard.GetDataObject();
            Image getIma = null;
            if (obj1.GetDataPresent(typeof(Bitmap)))
            {
                Image image1 = (Image)obj1.GetData(typeof(Bitmap));
                getIma = image1;
            }
            return getIma;
        }
    }
}

Answer 1

原因不是很清楚，不过可以再给你个类似的源码：
http://www.dotblogs.com.tw/larrynung/archive/2009/03/29/7750.aspx

Answer 2

不懂，释放资源，Mark....能不能再说说，观望了

Answer 3

应该是CloVideo()系统资源设置被修改了

Answer 4

下面是调用的代码，应该怎样修改啊
namespace YHhotel.YHhotelWindows
{
    public partial class Form1 : Form
    {
      public video vd;
        public Form1()
        {
            InitializeComponent();
        }        private void Form1_Load(object sender, EventArgs e)
        {
            vd = new video(pictureBox1.Handle, this.pictureBox1.Left, this.pictureBox1.Top, this.pictureBox1.Width, (short)this.pictureBox1.Height);
            vd.opVideo();
        }        private void button1_Click(object sender, EventArgs e)
        {
            pictureBox2.Image = vd.CatchVideo();        }        private void button2_Click(object sender, EventArgs e)
        {
            pictureBox2.Image =null;
        }        private void button3_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

Answer 5

  vd = new video(pictureBox1.Handle, this.pictureBox1.Left, this.pictureBox1.Top, this.pictureBox1.Width, (short)this.pictureBox1.Height);
  vd.opVideo();
以上代码移到button1_Click方法中试试

Answer 6

从代码看，应该是用CloVideo（）来释放资源

Answer 7

原因好像是没有释放资源，这段代码：
public void CloVideo()
  {
  SendMessage(this.hHwnd, 0x40b, 0, 0);
  DestroyWindow(this.hHwnd);
  }“ DestroyWindow(this.hHwnd);”不是用来释放资源的吗？？？应该怎样释放资源