c# avicap32.dll调用摄像头问题 出现黑屏 电脑是win10 hp 20C

using System;
using System.Collections.Generic;
using System.Text;

using System.Runtime.InteropServices;
using System.Drawing.Design
;

namespace QQClass
{
public class VideoAPI //视频API类
{
///
/// 视频API调用
///
/// 标识窗口的名称
/// 标识窗口风格
/// 标识窗口的左上角坐标
/// 标识窗口右上角坐标
/// 标识窗口的宽度
/// 标识窗口的高度
/// 标识父窗口句柄
/// 窗口ID
/// 视频捕捉窗口句柄
[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);
///
/// 用于向Windows系统发送消息机制
///
/// 窗口句柄
/// 发送消息
///
///
///
[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 const int WM_CAP_SEQUENCE = WM_CAP_START + 62;
    public const int WM_CAP_STOP = WM_CAP_START + 68;
}
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
    }


    public void capDlgVideoDisplay()
    {
        Boolean capDlgVideoDisplay = VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 43, 0, 0);
    }
    public void capDlgVideoCompression()
    {
        Boolean capDlgVideoCompression = VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 46, 0, 0);

    }

    /// <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);

        // 使用下面的这段代码,图像会“变歪”
        /*
        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);
        }
        */
        if (lwndC.ToInt32() != 0)
        {
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 6, 0, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 2, 0, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 3, 0, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_CONNECT, 0, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 53, 1, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEWRATE, 66, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_START + 51, 1, 0);
            VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SET_PREVIEW, 1, 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());
    }

    /// <summary>
    /// 录像
    /// </summary>
    /// <param name="path">要保存avi文件的路径</param>
    public void Kinescope(string path)
    {
        IntPtr hBmp = Marshal.StringToHGlobalAnsi(path);
        VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_DRIVER_CONNECT, 0, hBmp.ToInt32());
        VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_SEQUENCE, 0, 0);

    }

    public void StartKinescope()
    { 
        Kinescope("C:\\");
    }

    /// <summary>
    /// 停止录像
    /// </summary>
    public void StopKinescope()
    {
        VideoAPI.SendMessage(lwndC, VideoAPI.WM_CAP_STOP, 0, 0);
    }

}

图片说明

}

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