C# VideoAPI

using System;
using System.Runtime.InteropServices;

public class VideoAPI //视频API类
{

    // 视频API调用

    [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);

    // 常量

    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;

    public const int WM_CAP_START = WM_USER;

    public const int WM_CAP_SAVEDIB = WM_CAP_START + 25;

}

public class cVideo //视频类
{
    private IntPtr lwndC; //保存无符号句柄

    private IntPtr mControlPtr; //保存管理指示器

    private int mWidth;

    private int mHeight;

    public cVideo(IntPtr handle, int width, int height)
    {
        mControlPtr = handle; //显示视频控件的句柄
        mWidth = width; //视频宽度
        mHeight = height; //视频高度
    }

    /// <summary>
    /// 打开视频设备
    /// </summary>
    public void StartWebCam()
    {
        byte[] lpszName = new byte[100];
        byte[] lpszVer = new byte[100];
        VideoAPI.capGetDriverDescriptionA(0, lpszName, 100, lpszVer, 100);
        this.lwndC = VideoAPI.capCreateCaptureWindowA(lpszName, VideoAPI.WS_CHILD | VideoAPI.WS_VISIBLE, 0, 0, mWidth, mHeight, mControlPtr, 0);

        if (VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_CONNECT, 0, 0))
        {
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEWRATE, 100, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEW, true, 0);
        }
    }

    /// <summary>
    /// 关闭视频设备
    /// </summary>
    public void CloseWebcam()
    {
        VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_DISCONNECT, 0, 0);
    }

    /// <summary>
    /// 拍照
    /// </summary>
    /// <param name="path">要保存bmp文件的路径</param>
    public void GrabImage(IntPtr hWndC, string path)
    {
        IntPtr hBmp = Marshal.StringToHGlobalAnsi(path);
        VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SAVEDIB, 0, hBmp.ToInt32());
    }
}