我不知道该怎么说，但我会尽力而为。
我有一个 Windows 窗体应用程序，它使用网络摄像头为用户拍摄照片，效果很好，我使用的是http://directshownet.sourceforge.net/此处的 directshownet 库，并使用 DxSnap 示例拍摄照片.
应用程序的下一部分使用 RFID 标签阅读器，一旦标签被扫描，它就会调用拍照方法。这就是问题所在，因为 RFID 监听方法是在与 GUI 线程不同的线程中运行的，因为它是一个无限的 while 循环。
用于拍照的类将图片框控件的实例作为其构造函数的参数，该构造函数是在主线程中创建的，我认为这就是问题所在。
应用程序的每个部分都可以单独工作，但是当我尝试调用该方法从侦听器线程中获取照片时，所有的地狱都崩溃了，应用程序崩溃了。
有谁知道我如何从侦听器线程调用在主线程（拍摄照片）中初始化的对象的方法？
我尝试过委托和调用，但无法弄清楚，因为我不想直接操作控件，而是让对象在主线程中完成。
这是一些代码：
private Capture cam;
private int portIndex = -1;
private ArrayList AlreadyOpenPortList = new ArrayList();
private byte readerAddr = 0;
private Thread listenThread;
IntPtr m_ip = IntPtr.Zero;
public podiumForm()
{
InitializeComponent();
// scanner and camera startup
startCam();
openComs();
openRF();
startListening();
}
private void startListening()
{
listenThread = new Thread(new ThreadStart(this.Listen));
listenThread.Start();
}
/// <summary>
/// Method of retrieving code tag details from reader
/// </summary>
private void Listen()
{
int fCmdRet = 0x30;
byte state = 1;
byte AFI = 00;
byte[] DSFIDAndUID = new byte[9];
byte cardNumber = 0;
string strDSFIDAndUID = "";
byte outputSet;
if (!GetCurrentUsePort())
{
MessageBox.Show("Open ComPort, Please");
return;
}
while (true)
{
fCmdRet = StaticClassReaderA.Inventory(ref readerAddr, ref state, ref AFI, DSFIDAndUID, ref cardNumber, portIndex);
if (fCmdRet == 0)
{
outputSet = 0;
fCmdRet = StaticClassReaderA.SetGeneralOutput(ref readerAddr, ref outputSet, portIndex);
strDSFIDAndUID = ByteArrayToHexString(DSFIDAndUID).Replace(" ", "");
outputSet = 3;
fCmdRet = StaticClassReaderA.SetGeneralOutput(ref readerAddr, ref outputSet, portIndex);
SavePic(strDSFIDAndUID.Substring(2, 16));
//MessageBox.Show(strDSFIDAndUID.Substring(2, 16));
//ShutDown();
}
}
}
private void SavePic(string text)
{
Cursor.Current = Cursors.WaitCursor;
// Release any previous buffer
if (m_ip != IntPtr.Zero)
{
Marshal.FreeCoTaskMem(m_ip);
m_ip = IntPtr.Zero;
}
// here's where it crashes
// capture image
m_ip = cam.Click();
Bitmap b = new Bitmap(cam.Width, cam.Height, cam.Stride, PixelFormat.Format24bppRgb, m_ip);
cam.Dispose();
// If the image is upsidedown
b.RotateFlip(RotateFlipType.RotateNoneFlipY);
pbPic.Image = b;
Cursor.Current = Cursors.Default;
MessageBox.Show("Here " + text);
}
private void startCam()
{
const int VIDEODEVICE = 0; // zero based index of video capture device to use
const int VIDEOWIDTH = 640; // Depends on video device caps
const int VIDEOHEIGHT = 480; // Depends on video device caps
const int VIDEOBITSPERPIXEL = 24; // BitsPerPixel values determined by device
cam = new Capture(VIDEODEVICE, VIDEOWIDTH, VIDEOHEIGHT, VIDEOBITSPERPIXEL, pbPic);
}
// method in capture class
public IntPtr Click()
{
int hr;
// get ready to wait for new image
m_PictureReady.Reset();
m_ipBuffer = Marshal.AllocCoTaskMem(Math.Abs(m_stride) * m_videoHeight);
try
{
m_WantOne = true;
// If we are using a still pin, ask for a picture
if (m_VidControl != null)
{
// CRASHES HERE with : System.InvalidCastException was unhandled
// Tell the camera to send an image
hr = m_VidControl.SetMode(m_pinStill, VideoControlFlags.Trigger);
DsError.ThrowExceptionForHR(hr);
}
// Start waiting
if (!m_PictureReady.WaitOne(9000, false))
{
throw new Exception("Timeout waiting to get picture");
}
}
catch
{
Marshal.FreeCoTaskMem(m_ipBuffer);
m_ipBuffer = IntPtr.Zero;
throw;
}
// Got one
return m_ipBuffer;
}