2023-05-06 04:16:04:392:  C#获取usb信号源显示在界面上

2023-05-06 04:16:24:258:  首先，您需要使用C#中的USB API检测已连接的USB设备。可以使用WMI（Windows Management Instrumentation）进行此操作。以下是示例代码：

```csharp
using System.Management;

//...

private void DetectUSBDevices()
{
    ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_PnPEntity WHERE ConfigManagerErrorCode = 0");
    foreach (ManagementObject obj in searcher.Get())
    {
        string name = obj["Name"].ToString();
        if (name.Contains("USB"))
        {
            // Add the USB device to a list or display it on the UI
        }
    }
}
```

检测到USB设备后，您需要使用一个视频捕捉库，例如DirectShow（Windows SDK中包含）或OpenCV（开源库），以获取视频信号源并将其显示在C#窗体上。以下是使用DirectShow实现此操作的示例代码：

```csharp
using DirectShowLib;

//...

private void DisplayVideo()
{
    // Get a list of video capture devices
    DsDevice[] devices = DsDevice.GetDevicesOfCat(FilterCategory.VideoInputDevice);

    // Select the first device and create a capture device object
    ICaptureGraphBuilder2 captureGraph = new CaptureGraphBuilder2() as ICaptureGraphBuilder2;
    IBaseFilter captureDevice = null;
    captureGraph.SetFiltergraph(graphBuilder);
    captureGraph.FindInterface(null, null, devices[0].Moniker, typeof(IBaseFilter).GUID, out captureDevice);

    // Add the capture device to the graph
    graphBuilder.AddFilter(captureDevice, "Video Capture");

    // Create a video renderer and add it to the graph
    IBaseFilter videoRenderer = new VideoRenderer(null) as IBaseFilter;
    graphBuilder.AddFilter(videoRenderer, "Video Renderer");

    // Connect the capture device to the video renderer
    captureGraph.RenderStream(null, MediaType.Video, captureDevice, null, videoRenderer);

    // Start the graph to display the video on the UI
    mediaControl.Run();
}
```

此代码将使用DirectShow捕获第一个检测到的视频设备的视频信号，然后将其连接到一个视频渲染器以显示在UI上。

请注意，此代码可能需要更改以适应您的情况。例如，您可能需要更改捕获设备规范或更改视频渲染器的大小和位置。
