using System;
using System.Runtime.InteropServices;
 
namespace WindowsApplication1
{
    public class VideoCapture
    {
 
        [StructLayout(LayoutKind.Sequential)] 
            public struct BITMAPINFOHEADER
        {
            [MarshalAs(UnmanagedType.I4)] public Int32 biSize ;
            [MarshalAs(UnmanagedType.I4)] public Int32 biWidth ;
            [MarshalAs(UnmanagedType.I4)] public Int32 biHeight ;
            [MarshalAs(UnmanagedType.I2)] public short biPlanes;
            [MarshalAs(UnmanagedType.I2)] public short biBitCount ;
            [MarshalAs(UnmanagedType.I4)] public Int32 biCompression;
            [MarshalAs(UnmanagedType.I4)] public Int32 biSizeImage;
            [MarshalAs(UnmanagedType.I4)] public Int32 biXPelsPerMeter;
            [MarshalAs(UnmanagedType.I4)] public Int32 biYPelsPerMeter;
            [MarshalAs(UnmanagedType.I4)] public Int32 biClrUsed;
            [MarshalAs(UnmanagedType.I4)] public Int32 biClrImportant;
        } 
 
        [StructLayout(LayoutKind.Sequential)] public struct BITMAPINFO
        {
            [MarshalAs(UnmanagedType.Struct, SizeConst=40)] 
                public BITMAPINFOHEADER bmiHeader;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst=1024)] 
                public Int32[] bmiColors;
        }
 
        private const int WS_CHILD = 0x40000000;
        private const int WS_VISIBLE = 0x10000000;
        private const int SWP_SHOWWINDOW = 0x0040;
        private const int WM_CAP_START = 0x0400;
        private const int WM_CAP_DRIVER_CONNECT = (WM_CAP_START+10);
        private const int WM_CAP_DRIVER_DISCONNECT = (WM_CAP_START+11);
        private const int WM_CAP_SET_PREVIEWRATE = (WM_CAP_START+52);
        private const int WM_CAP_SET_PREVIEW = (WM_CAP_START+50);
        private const int WM_CAP_GRAB_FRAME = (WM_CAP_START+60);
        private const int WM_CAP_GET_VIDEOFORMAT = (WM_CAP_START+44);
 
        private IntPtr hCapture=(IntPtr) 0;
        private int width=0;
        private int height=0;
 
        public bool CreateCaptureWindow(IntPtr hParent, int x, int y) 
        {
            hCapture = capCreateCaptureWindow("", 
                WS_CHILD | WS_VISIBLE,
                x, y, 32, 24, hParent, 0);
            if ((int) hCapture==0) {return false;}
 
            SendMessage(hCapture, WM_CAP_DRIVER_CONNECT, 0, 0);
            GetVideoFormat();
            SetWindowPos(hCapture, 0, x, y, width, height, 
                SWP_SHOWWINDOW);
            return true;
        }
 
        public void ReleaseCaptureWindow() 
        {
            if ((int) hCapture != 0) 
            {
                SendMessage(hCapture, WM_CAP_DRIVER_DISCONNECT, 0, 0);
                DestroyWindow(hCapture);
                hCapture= (IntPtr) 0;
            }
        }
 
        public void StartPreview() 
        {
            SendMessage(hCapture, WM_CAP_SET_PREVIEWRATE, 15, 0);
            SendMessage(hCapture, WM_CAP_SET_PREVIEW, 1, 0);
        }
 
        public void StopPreview() 
        {
            SendMessage(hCapture, WM_CAP_SET_PREVIEW, 0, 0);
        }
 
        public void GetFrame() 
        {
            SendMessage(hCapture, WM_CAP_GRAB_FRAME, 0, 0);
        }
 
        private void GetVideoFormat() 
        {
            BITMAPINFO buffer = new BITMAPINFO();
            int size = Marshal.SizeOf(typeof(BITMAPINFOHEADER));
            buffer.bmiHeader.biSize = size;
 
            SendMessage(hCapture, WM_CAP_GET_VIDEOFORMAT, 
                size, ref buffer);
 
            width = buffer.bmiHeader.biWidth;
            height = buffer.bmiHeader.biHeight;
        }
 
        [DllImport("User32.dll")]
        private static extern bool SendMessage(IntPtr hWnd, 
            int wMsg, int wParam, ref BITMAPINFO lParam);
 
        [DllImport("User32.dll")]
        private static extern bool SendMessage(IntPtr hWnd, 
            int wMsg, int wParam, int lParam);
 
        [DllImport("User32.dll")] 
        private static extern int SetWindowPos(IntPtr hWnd, 
            int hWndInsertAfter, int x, int y, 
            int cx, int cy, int wFlags);
 
        [DllImport("user32.dll")]
        private static extern int DestroyWindow(IntPtr hwnd);
 
        [DllImport("avicap32.dll")]
        private static extern IntPtr capCreateCaptureWindow
            (string lpszWindowName, int dwStyle,
            int x, int y, int nWidth, int nHeight, 
            IntPtr hWnd, int nID);
 
    }
}