C＃，传递事件不起作用

Question

I have this example code that DOES work.

main form:

FileTransferManager fm = new FileTransferManager();

...
public FrmMain()
{
InitializeComponent();
...
fm.OnFile += fm_OnFile;
}

...
    void fm_OnFile(object sender, FileTransferEventArgs e)
    {
        var recvFile = new FrmReceiveFile(fm, e);
        recvFile.Show();
        e.Accept = true;
    }

and FrmReceiveFile:

public partial class FrmReceiveFile : Form
{
    private FileTransferManager fm;
    private FileTransferEventArgs ftea;
    public FrmReceiveFile(FileTransferManager ftm, FileTransferEventArgs fea)
    {
        InitializeComponent();

        fm = ftm;
        ftea = fea;

        Text = "File transfer: " + ftea.Jid;

        lblSize.Text = Util.HumanReadableFileSize(ftea.FileSize);
        lblFileName.Text = ftea.Filename;
        lblDescription.Text = ftea.Description;

        fm.OnError += fm_OnError;
        fm.OnEnd += fm_OnEnd;
        fm.OnStart += fm_OnStart;
        fm.OnProgress += fm_OnProgress;
    }


    void fm_OnStart(object sender, FileTransferEventArgs e)
    {
        MessageBox.Show("file transfer started"); ///// THIS APPEARS & EVERYTHING WORKS!
        if (e.Sid != ftea.Sid)
            return;
    }
...

And here is my code, all in one form, yet somehow it does not work.

public partial class Form1 : Form
    {

        private string sid = "";

        FileTransferManager fmout = new FileTransferManager(); //// this FileTransferManager is for outgoing files
        FileTransferManager fmin = new FileTransferManager();  //// this FileTransferManager is for incomeing files
        FileTransferEventArgs fta = new FileTransferEventArgs();
        Jid _jid = new Jid();


        public Form1()
        {
            InitializeComponent();

            fmout.OnError += fmout_OnError;
            fmout.OnEnd += fmout_OnEnd;
            fmout.OnStart += fmout_OnStart;
            fmout.OnProgress += fmout_OnProgress;

            fmout.XmppClient = xmppClient;
            fmin.XmppClient = xmppClient;

            fmin.OnFile += fmin_OnFile;
            fmin.OnEnd += fmin_OnEnd;
            fmin.OnStart += fmin_OnStart;
            fmin.OnProgress += fmin_OnProgress;
        }

        ////////////////////////////////////////////////////////////////////////////////////////////

        void fmin_OnFile(object sender, FileTransferEventArgs e)
        {
            DisplayEvent("INCOMING FILE: " + e.Filename + " - " + e.FileSize); ///// THIS APPEARS CORRECTLY
            e.Accept = true;
            fta = e;
        }


        void fmin_OnStart(object sender, FileTransferEventArgs e) /// THIS WON'T START! :(
        {
            MessageBox.Show("Incoming file!"); /// THIS WON'T START! :( 
            if (e.Sid != fta.Sid)
                return;
        }

Looks like e.Accept = true; does not launch fmin_OnStart ... any ideas what might be the problem?

Thanks!

Answer 1

The difference (that can be made out from the code you have shared) in the two pieces of code is that in the first one you are registering the "fm.OnStart += fm_OnStart" event when your "OnFileHandler" is called, while in the other one (not working) you are doing that upfront, even when your OnFileHandler is not called.

Though, as an user of FileTransferManager, i dont think that should matter.

Still, you can try the same thing in the second code.. so do it as below.

  void fmin_OnFile(object sender, FileTransferEventArgs e)        
 {     fmin.OnStart += fmin_OnStart; 
DisplayEvent("INCOMING FILE: " + e.Filename + " - " + e.FileSize); 
e.Accept = true;             fta = e;  }

If that works, i would rather question the programmer of FileTransferManager.