摄像头编程

      毕业设计的时候做的指纹仪，所以找了些关于摄像头编程的东西，当时看到周立民的blog上有一个关于摄像头编程的帖子，虽然这段代码有好多东西可以去掉，但是从原理上讲还是比较全面的，所以直接copy过来，留待以后学习使用。

      以下是全部原文：

      这段时间搞视频采集方面的程序，在国外网站上找到一个用C#写的驱动摄像头的程序。经改造和调试，如下：

      安装摄像头后，一般可以找到一个avicap32.dll文件，这是一个关于摄像头的类:

using System;
using System.Runtime.InteropServices;

namespace webcam
{
 ///

 /// avicap 的摘要说明。

 ///

 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);
  }
 }
}


具体调用如下：

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using webcam;

namespace webcam
{
 ///

 /// Form1 的摘要说明。

 ///

 public class Form1 : System.Windows.Forms.Form
 {
  private System.Windows.Forms.Panel panelPreview;
  private System.Windows.Forms.Button b_play;
  private System.Windows.Forms.Button b_stop;
  ///

  /// 必需的设计器变量。

  ///

  private System.ComponentModel.Container components = null;
  WebCamera wc;

  public Form1()
  {
   //

   // Windows 窗体设计器支持所必需的

   //

   InitializeComponent();

   //

   // TODO: 在 InitializeComponent 调用后添加任何构造函数代码

   //

  }

  ///

  /// 清理所有正在使用的资源。

  ///

  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #region Windows 窗体设计器生成的代码
  ///

  /// 设计器支持所需的方法 - 不要使用代码编辑器修改

  /// 此方法的内容。

  ///

  private void InitializeComponent()
  {
   this.b_play = new System.Windows.Forms.Button();
   this.panelPreview = new System.Windows.Forms.Panel();
   this.b_stop = new System.Windows.Forms.Button();
   this.SuspendLayout();
   //

   // b_play

   //

   this.b_play.Location = new System.Drawing.Point(280, 368);
   this.b_play.Name = "b_play";
   this.b_play.TabIndex = 0;
   this.b_play.Text = "&Play";
   this.b_play.Click += new System.EventHandler(this.button1_Click);
   //

   // panelPreview

   //

   this.panelPreview.Location = new System.Drawing.Point(8, 8);
   this.panelPreview.Name = "panelPreview";
   this.panelPreview.Size = new System.Drawing.Size(344, 272);
   this.panelPreview.TabIndex = 1;
   //

   // b_stop

   //

   this.b_stop.Enabled = false;
   this.b_stop.Location = new System.Drawing.Point(360, 368);
   this.b_stop.Name = "b_stop";
   this.b_stop.TabIndex = 2;
   this.b_stop.Text = "&Stop";
   this.b_stop.Click += new System.EventHandler(this.b_stop_Click);
   //

   // Form1

   //

   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(464, 413);
   this.Controls.Add(this.b_stop);
   this.Controls.Add(this.panelPreview);
   this.Controls.Add(this.b_play);
   this.MaximizeBox = false;
   this.MinimizeBox = false;
   this.Name = "Form1";
   this.Text = "GoodView test Web Camera";
   this.Load += new System.EventHandler(this.Form1_Load);
   this.ResumeLayout(false);

  }
  #endregion

  ///

  /// 应用程序的主入口点。

  ///

  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }

  private void Form1_Load(object sender, System.EventArgs e)
  {
   b_play.Enabled = false;
   b_stop.Enabled = true;
   panelPreview.Size = new Size(330,330);
   wc = new WebCamera( panelPreview.Handle,panelPreview.Width,panelPreview.Height);
   wc.StartWebCam();
  }

  private void button1_Click(object sender, System.EventArgs e)
  {
   b_play.Enabled = false;
   b_stop.Enabled = true;
   panelPreview.Size = new Size(330,330);
   wc = new WebCamera( panelPreview.Handle,panelPreview.Width,panelPreview.Height);
   wc.StartWebCam();
  }

  private void b_stop_Click(object sender, System.EventArgs e)
  {
   b_play.Enabled = true;
   b_stop.Enabled = false;
   wc.CloseWebcam();
  }
 }
}