C#学习笔记——摄像头

界面：

源码：

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;

//添加引用
using System.Runtime.InteropServices;
using System.Drawing.Imaging;


namespace Camera
{

    public partial class FormMain : Form
    {
        WebCamera wc;
        //声明一个API函数
        [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
         private static extern bool BitBlt(
            IntPtr hdcDest, // 目标 DC的句柄
            int nXDest,
            int nYDest,
            int nWidth,
            int nHeight,
            IntPtr hdcSrc, // 源DC的句柄
            int nXSrc,
            int nYSrc,
            System.Int32 dwRop // 光栅的处理数值
            );

        public FormMain()
        {
            InitializeComponent();
        }

        private void btnPlay_Click(object sender, EventArgs e)
        {
            btnPlay.Enabled = false;
            btnStop.Enabled = true;
            //panelPreview.Size = new Size(330, 330);
            wc = new WebCamera(panelPreview.Handle, panelPreview.Width, panelPreview.Height);
            wc.StartWebCam();
        }

        private void FormMain_Load(object sender, EventArgs e)
        {
            btnPlay.Enabled = false;
            btnStop.Enabled = true;
            //panelPreview.Size = new Size(330, 330);
            wc = new WebCamera(panelPreview.Handle, panelPreview.Width, panelPreview.Height);
            wc.StartWebCam();
        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            btnPlay.Enabled = true;
            btnStop.Enabled = false;
            wc.CloseWebcam();
        }

        private void btnPhoto_Click(object sender, EventArgs e)
        {
            //创建一个以当前控件区域屏幕为模板的图象
            Graphics gPanel = this.panelPreview.CreateGraphics();

            Bitmap bmSave = new Bitmap(this.panelPreview.Width, this.panelPreview.Height);     //用于保存图片的位图对象
            Graphics gSave = Graphics.FromImage(bmSave);
            //得到屏幕的DC
            IntPtr dcPanel = gPanel.GetHdc();
            //得到Bitmap的DC
            IntPtr dcSave = gSave.GetHdc();
            //调用此API函数，实现屏幕捕获
            BitBlt(dcSave, 0, 0, this.panelPreview.Width, this.panelPreview.Height, dcPanel, 0, 0, 13369376);
            //释放掉屏幕的DC
            gPanel.ReleaseHdc(dcPanel);
            //释放掉Bitmap的DC
            gSave.ReleaseHdc(dcSave);
            //以JPG文件格式来保存
            bmSave.Save(@"D:/Photo.jpg", ImageFormat.Jpeg);
            MessageBox.Show("当前图像已经保存为D盘Photo文件！");
        }
    }


 //show Video class
 public class showVideo
 {
  // showVideo calls
  [DllImport("avicap32.dll")]
  public static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName, int dwStyle, int x, int y, int nWidth, int nHeight, IntPtr hWndParent, int nID);
  [DllImport("avicap32.dll")]
  public static extern bool capGetDriverDescriptionA(short wDriver, byte[] lpszName, int cbName, byte[] lpszVer, int cbVer);
  [DllImport("User32.dll")]
  public static extern bool SendMessage(IntPtr hWnd, int wMsg, bool wParam, int lParam);
  [DllImport("User32.dll")]
  public static extern bool SendMessage(IntPtr hWnd, int wMsg, short wParam, int lParam);
  [DllImport("User32.dll")]
  public static extern bool SendMessage(IntPtr hWnd, int wMsg, short wParam, FrameEventHandler lParam);
  [DllImport("User32.dll")]
  public static extern bool SendMessage(IntPtr hWnd, int wMsg, int wParam, ref BITMAPINFO lParam);
  [DllImport("User32.dll")]
  public static extern int SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int y, int cx, int cy, int wFlags);
  [DllImport("avicap32.dll")]
  public static extern int capGetVideoFormat(IntPtr hWnd, IntPtr psVideoFormat, int wSize );

  // Constants
  public const int WM_USER = 0x400;
  public const int WS_CHILD = 0x40000000;
  public const int WS_VISIBLE = 0x10000000;
  public const int SWP_NOMOVE = 0x2;
  public const int SWP_NOZORDER = 0x4;
  public const int WM_CAP_DRIVER_CONNECT = WM_USER + 10;
  public const int WM_CAP_DRIVER_DISCONNECT = WM_USER + 11;
  public const int WM_CAP_SET_CALLBACK_FRAME = WM_USER + 5;
  public const int WM_CAP_SET_PREVIEW = WM_USER + 50;
  public const int WM_CAP_SET_PREVIEWRATE = WM_USER + 52;
  public const int WM_CAP_SET_VIDEOFORMAT = WM_USER + 45;

  // Structures
  [StructLayout(LayoutKind.Sequential)] public struct VIDEOHDR
  {
   [MarshalAs(UnmanagedType.I4)] public int lpData;
   [MarshalAs(UnmanagedType.I4)] public int dwBufferLength;
   [MarshalAs(UnmanagedType.I4)] public int dwBytesUsed;
   [MarshalAs(UnmanagedType.I4)] public int dwTimeCaptured;
   [MarshalAs(UnmanagedType.I4)] public int dwUser;
   [MarshalAs(UnmanagedType.I4)] public int dwFlags;
   [MarshalAs(UnmanagedType.ByValArray, SizeConst=4)] public int[] dwReserved;
  }

  [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;
  }

  public delegate void FrameEventHandler(IntPtr lwnd, IntPtr lpVHdr);

  // Public methods
  public static object GetStructure(IntPtr ptr,ValueType structure)
  {
   return Marshal.PtrToStructure(ptr,structure.GetType());
  }

  public static object GetStructure(int ptr,ValueType structure)
  {
   return GetStructure(new IntPtr(ptr),structure);
  }

  public static void Copy(IntPtr ptr,byte[] data)
  {
   Marshal.Copy(ptr,data,0,data.Length);
  }

  public static void Copy(int ptr,byte[] data)
  {
   Copy(new IntPtr(ptr),data);
  }

  public static int SizeOf(object structure)
  {
   return Marshal.SizeOf(structure);
  }
 }

  //Web Camera Class
 public class WebCamera
 {
  // Constructur
  public WebCamera(IntPtr handle, int width,int height)
  {
   mControlPtr = handle;
   mWidth = width;
   mHeight = height;
  }

  // delegate for frame callback
  public delegate void RecievedFrameEventHandler(byte[] data);
  public event RecievedFrameEventHandler RecievedFrame;

  private IntPtr lwndC; // Holds the unmanaged handle of the control
  private IntPtr mControlPtr; // Holds the managed pointer of the control
  private int mWidth;
  private int mHeight;

  private showVideo.FrameEventHandler mFrameEventHandler; // Delegate instance for the frame callback - must keep alive! gc should NOT collect it

  // Close the web camera
  public void CloseWebcam()
  {
   this.capDriverDisconnect(this.lwndC);
  }

  // start the web camera
  public void StartWebCam()
  {
   byte[] lpszName = new byte[100];
   byte[] lpszVer = new byte[100];

   showVideo.capGetDriverDescriptionA(0, lpszName, 100,lpszVer, 100);
   this.lwndC = showVideo.capCreateCaptureWindowA(lpszName, showVideo.WS_VISIBLE + showVideo.WS_CHILD, 0, 0, mWidth, mHeight, mControlPtr, 0);

   if (this.capDriverConnect(this.lwndC, 0))
   {
    this.capPreviewRate(this.lwndC, 66);
    this.capPreview(this.lwndC, true);
    showVideo.BITMAPINFO bitmapinfo = new showVideo.BITMAPINFO();
    bitmapinfo.bmiHeader.biSize = showVideo.SizeOf(bitmapinfo.bmiHeader);
    bitmapinfo.bmiHeader.biWidth = 352;
    bitmapinfo.bmiHeader.biHeight = 288;
    bitmapinfo.bmiHeader.biPlanes = 1;
    bitmapinfo.bmiHeader.biBitCount = 24;
    this.capSetVideoFormat(this.lwndC, ref bitmapinfo, showVideo.SizeOf(bitmapinfo));
    this.mFrameEventHandler = new showVideo.FrameEventHandler(FrameCallBack);
    this.capSetCallbackOnFrame(this.lwndC, this.mFrameEventHandler);
    showVideo.SetWindowPos(this.lwndC, 0, 0, 0, mWidth , mHeight , 6);
   }
  }

  // private functions
  private bool capDriverConnect(IntPtr lwnd, short i)
  {
   return showVideo.SendMessage(lwnd, showVideo.WM_CAP_DRIVER_CONNECT, i, 0);
  }

  private bool capDriverDisconnect(IntPtr lwnd)
  {
   return showVideo.SendMessage(lwnd, showVideo.WM_CAP_DRIVER_DISCONNECT, 0, 0);
  }

  private bool capPreview(IntPtr lwnd, bool f)
  {
   return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_PREVIEW , f, 0);
  }

  private bool capPreviewRate(IntPtr lwnd, short wMS)
  {
   return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_PREVIEWRATE, wMS, 0);
  }

  private bool capSetCallbackOnFrame(IntPtr lwnd, showVideo.FrameEventHandler lpProc)
  {
   return showVideo.SendMessage(lwnd, showVideo.WM_CAP_SET_CALLBACK_FRAME, 0, lpProc);
  }

  private bool capSetVideoFormat(IntPtr hCapWnd, ref showVideo.BITMAPINFO BmpFormat, int CapFormatSize)
  {
   return showVideo.SendMessage(hCapWnd, showVideo.WM_CAP_SET_VIDEOFORMAT, CapFormatSize, ref BmpFormat);
  }

  private void FrameCallBack(IntPtr lwnd, IntPtr lpVHdr)
  {
   showVideo.VIDEOHDR videoHeader = new showVideo.VIDEOHDR();
   byte[] VideoData;
   videoHeader = (showVideo.VIDEOHDR)showVideo.GetStructure(lpVHdr,videoHeader);
   VideoData = new byte[videoHeader.dwBytesUsed];
   showVideo.Copy(videoHeader.lpData ,VideoData);
   if (this.RecievedFrame != null)
    this.RecievedFrame (VideoData);
  }
 }

}