C# 不同控件调用同一方法出错。

问题描述：

private void btn_Record_Click(object sender, EventArgs e)
{
record();
}
//在一个button上调用了一个record（）方法。此方法可以正常使用

             private void port_PinChanged(object sender, System.IO.Ports.SerialPinChangedEventArgs e)
    {
            switch (e.EventType)
            {
                case System.IO.Ports.SerialPinChange.DsrChanged:
                    //开始录像
                    if (com.DsrHolding == true)
                    {
                                                record();
                    }
                    break;
                default:
                    break;
            }
            //在一个SerialPort的PinChanged事件上也调用了一个record（）方法。
            但是为啥会报一下错误---------------------------

无法将类型为“DirectShowLib.CaptureGraphBuilder2”的 COM 对象强制转换为接口类型“DirectShowLib.ICaptureGraphBuilder2”。此操作失败的原因是对 IID 为“{93E5A4E0-2D50-11D2-ABFA-00A0C9C6E38D}”的接口的 COM 组件调用 QueryInterface 因以下错误而失败: 不支持此接口 (异常来自 HRESULT:0x80004002 (E_NOINTERFACE))。

答

CaptureD(); 是不是只能初始化1次，你定义成static，多次调用。看名字好像是图像捕捉？那么设备只能打开并且被一个对象调用。

答

                            record（）方法的出错代码

                            hr = this.m_mediaControl.Stop();
            DsError.ThrowExceptionForHR(hr);

            //Add the Video compressor filter to the graph
            hr = m_graphBuilder.AddFilter(theCompressor, "compressor filter");
            DsError.ThrowExceptionForHR(hr);

            //Create the file writer part of the graph. SetOutputFileName does this for us, and returns the mux and sink
            hr = m_captureGraphBuilder.SetOutputFileName(MediaSubType.Avi, filePath, out mux, out sink);
            DsError.ThrowExceptionForHR(hr);

            //Connect the device and compressor to the mux to render the capture part of the graph
            hr = m_captureGraphBuilder.RenderStream(null, null, pCaptureOut, null, theCompressor);
            DsError.ThrowExceptionForHR(hr);

            //Connect the device and compressor to the mux to render the capture part of the graph
            hr = m_captureGraphBuilder.RenderStream(null, MediaType.Video, theCompressor, null, mux);
            DsError.ThrowExceptionForHR(hr);

            hr = this.m_mediaControl.Run();
            DsError.ThrowExceptionForHR(hr);

答

要看你完整的代码，record();这里record()是怎么定义的，窗体的成员函数？

答

m_captureGraphBuilder在哪里初始化的？它是一个com组件

答

把方法写在了一个CaptureD cam = new CaptureD(); 的类上，
CaptureD 类里InitInterfaces() 初始化m_captureGraphBuilder
private void InitInterfaces()
{
int hr = 0;
//获取ICaptureGraphBuilder2接口对象
this.m_captureGraphBuilder = (ICaptureGraphBuilder2)new CaptureGraphBuilder2();
//设置ICaptureGraphBuilder2的IGraphBuilder接口对象为当前对象
hr = this.m_captureGraphBuilder.SetFiltergraph(this.m_graphBuilder);
DsError.ThrowExceptionForHR(hr);

答

private void record()
{
string strParth = videoPath + returnFileName(".avi");
bool info = cam.StartRecord(strParth);

答

public bool StartRecord(string filePath)
    {
             int hr = 0;
            hr = this.m_mediaControl.Stop();
            DsError.ThrowExceptionForHR(hr);

            //Add the Video compressor filter to the graph
            hr = m_graphBuilder.AddFilter(theCompressor, "compressor filter");
            DsError.ThrowExceptionForHR(hr);

            //Create the file writer part of the graph. SetOutputFileName does this for us, and returns the mux and sink
            hr = m_captureGraphBuilder.SetOutputFileName(MediaSubType.Avi, filePath, out mux, out sink);
            DsError.ThrowExceptionForHR(hr);

            //Connect the device and compressor to the mux to render the capture part of the graph
            hr = m_captureGraphBuilder.RenderStream(null, null, pCaptureOut, null, theCompressor);
            DsError.ThrowExceptionForHR(hr);

            //Connect the device and compressor to the mux to render the capture part of the graph
            hr = m_captureGraphBuilder.RenderStream(null, MediaType.Video, theCompressor, null, mux);
            DsError.ThrowExceptionForHR(hr);

            hr = this.m_mediaControl.Run();
            DsError.ThrowExceptionForHR(hr);

答

嗯嗯，是用来捕捉图像的。O(∩_∩)O谢谢！，我试试。

答

class CaptureD : ISampleGrabberCB, IDisposable
{
这个类实现了一些接口不能使用静态吧？

答

而且我只实列化了一个CaptureD

答

不是CaptureD静态，而是static CaptureD 变量 = new CaptureD();，这个变量要static，只初始化一个

C# 不同控件调用同一方法出错。

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