Question

C#中如何用摄像头拍照

求一个例子，如何在C#中利用摄像头拍照，然后存到指定文件夹里，请给我一个有注释，调试过的例子，代码越少越好，不胜感激

Answer 1

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);
}
}

Answer 2

　　using System;
　　using System.Collections.Generic;
　　using System.Text;
　　using System.Runtime.InteropServices;
　　
　　namespace CamTest
　　{
　　
　　//参考AVICap技术
　　public class Cam
　　{
　　private const int WM_USER = 0x400;
　　private const int WS_CHILD = 0x40000000;
　　private const int WS_VISIBLE = 0x10000000;
　　private const int WM_CAP_START = WM_USER;
　　private const int WM_CAP_STOP = WM_CAP_START + 68;
　　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_SAVEDIB = WM_CAP_START + 25;
　　private const int WM_CAP_GRAB_FRAME = WM_CAP_START + 60;
　　private const int WM_CAP_SEQUENCE = WM_CAP_START + 62;
　　private const int WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20;
　　private const int WM_CAP_SEQUENCE_NOFILE = WM_CAP_START + 63;
　　private const int WM_CAP_SET_OVERLAY = WM_CAP_START + 51;
　　private const int WM_CAP_SET_PREVIEW = WM_CAP_START + 50;
　　private const int WM_CAP_SET_CALLBACK_VIDEOSTREAM = WM_CAP_START + 6;
　　private const int WM_CAP_SET_CALLBACK_ERROR = WM_CAP_START + 2;
　　private const int WM_CAP_SET_CALLBACK_STATUSA = WM_CAP_START + 3;
　　private const int WM_CAP_SET_CALLBACK_FRAME = WM_CAP_START + 5;
　　private const int WM_CAP_SET_SCALE = WM_CAP_START + 53;
　　private const int WM_CAP_SET_PREVIEWRATE = WM_CAP_START + 52;
　　
　　private IntPtr hWndC;
　　private IntPtr mControlPtr;
　　private bool bWorkStart = false;
　　private int mWidth;
　　private int mHeight;
　　private int mLeft;
　　private int mTop;
　　
　　/// <summary>
　　/// 初始化显示图像
　　/// </summary>
　　/// <param name="handle">控件的句柄 </param>
　　/// <param name="left">开始显示的左边距 </param>
　　/// <param name="top">开始显示的上边距 </param>
　　/// <param name="width">要显示的宽度 </param>
　　/// <param name="height">要显示的长度 </param>
　　public Cam(IntPtr handle, int left, int top, int width, int height)
　　{
　　mControlPtr = handle;
　　mWidth = width;
　　mHeight = height;
　　mLeft = left;
　　mTop = top;
　　}
　　// 创建捕捉窗口
　　//HWND VFWAPI capCreateCaptureWindow(
　　// LPCSTR lpszWindowName，// 捕捉窗口名字
　　// DWORD dwStyle，// 捕捉窗口的风格
　　// int x，// 窗口左上角x轴坐标
　　// int y，// 窗口左上角y轴坐标
　　// int nWidth，// 窗口的宽度
　　// int nHeight，// 窗口的高度
　　// HWND HWnd，// 父窗口句柄
　　// Int nID// 捕捉窗口的ID号
　　//);
　　//如果该函数调用成功 则函数返回窗口的句柄 否则函数返回NULL。
　　[DllImport("avicap32.dll")]
　　private static extern IntPtr capCreateCaptureWindowA(byte[] lpszWindowName, int dwStyle, int x, int y, int nWidth, int nHeight, IntPtr hWndParent, int nID);
　　
　　// 视频格式设置对话框
　　// BOOL capDlgVideoFormat( hwnd ); // hwnd：捕捉窗口句柄
　　//视频格式设置对话框对于每一个捕捉驱动程序来说，是唯一的。而且，有些驱动程序不一定支持这一功能。应用程序可以通过检测CAPDRIVERCAPS结构的成员变量fHasDlgVideoFormat来判断驱动程序是否支持这一功能。
　　
　　[DllImport("avicap32.dll")]
　　private static extern int capGetVideoFormat(IntPtr hWnd, IntPtr psVideoFormat, int wSize);
　　[DllImport("User32.dll")]
　　private static extern bool SendMessage(IntPtr hWnd, int wMsg, IntPtr wParam, IntPtr lParam);
　　
　　/// <summary>
　　/// 开始显示图像
　　/// </summary>
　　public void Start()
　　{
　　if (bWorkStart)
　　{
　　return;
　　}
　　bWorkStart = true;
　　byte[] lpszName = new byte[100];
　　hWndC = capCreateCaptureWindowA(lpszName, WS_CHILD | WS_VISIBLE, mLeft, mTop, mWidth, mHeight, mControlPtr, 0);
　　if (hWndC.ToInt32() != 0)
　　{
　　SendMessage(hWndC, WM_CAP_SET_CALLBACK_VIDEOSTREAM, IntPtr.Zero, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_CALLBACK_ERROR, IntPtr.Zero, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_CALLBACK_STATUSA, IntPtr.Zero, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_DRIVER_CONNECT, IntPtr.Zero, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_SCALE, (IntPtr)1, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_PREVIEWRATE, (IntPtr)66, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_OVERLAY, (IntPtr)1, IntPtr.Zero);
　　SendMessage(hWndC, WM_CAP_SET_PREVIEW, (IntPtr)1, IntPtr.Zero);
　　}
　　return;
　　}
　　
　　/// <summary>
　　/// 停止显示图像
　　/// </summary>
　　public void Stop()
　　{
　　SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, IntPtr.Zero, IntPtr.Zero);
　　bWorkStart = false;
　　}
　　
　　/// <summary>
　　/// 抓图
　　/// </summary>
　　/// <param name="path">要保存bmp文件的路径 </param>
　　public void GrabImage(string path)
　　{
　　IntPtr hBmp = Marshal.StringToHGlobalAnsi(path); //将System.String内容复制到非托管内存当中
　　SendMessage(hWndC, WM_CAP_SAVEDIB, IntPtr.Zero, hBmp);
　　}
　　
　　///<summary>
　　///录像
　　///</summary>
　　///<param name="path">要保存avi文件的路径</param>
　　public void Kinescope(string path)
　　{
　　IntPtr hCap = Marshal.StringToHGlobalAnsi(path);
　　SendMessage(hWndC, WM_CAP_FILE_SET_CAPTURE_FILEA, IntPtr.Zero, hCap);
　　SendMessage(hWndC, WM_CAP_SEQUENCE, IntPtr.Zero, hCap);
　　}
　　
　　///<summary>
　　///停止录像
　　///</summary>
　　public void StopKinescope()
　　{
　　SendMessage(hWndC, WM_CAP_STOP, IntPtr.Zero, IntPtr.Zero);
　　}
　　
　　}
　　}