Threading problem

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  • Frijoles
    #1

    Threading problem

    Hello, hopefully I can describe this probably correctly.

    I have what I thought was a simply form that opens a popup (another form)
    whenever an event happens. My main form, Form A, has an instance of Form B
    created on it. I set a bunch of parameters and then call a method on Form B
    to show itself and do a few more things. I can get the event to fire correct
    by pressing a button; everything was working great.

    However, I'm now trying to add in a class file that will check an XML stream
    over and over. If that xml file changes, I need the popup from above to open
    up to alert the user that something has changed. I fire off a thread, but of
    course I can't open the popup from the thread due to the cross-thread error.

    So basically, I have Form A (the main form), which calls Form B to open
    (Form A also sets some parameters on the 2nd form). I wish to access the
    instance of Form B that is running on Form A from Class C. I've looked in to
    delegates and invoking, but I guess I'm just totally lost about what goes
    where. I've also tried creating a worker class and just open up Form B
    directly from Class C, but that doesn't work very well and it's not the ideal
    solution anyway.

    Any tips? I've googled quite a bit, but I'm still scratching my head.

    Frij
    Tags: None
    • Frijoles
      #2
      RE: Threading problem

      Figures that right after posting this, I would get it working correctly. :) I
      ended up calling invoke on the main form, which seems to be working exactly
      as I need it to.


      "Frijoles" wrote:
      Hello, hopefully I can describe this probably correctly.
      >
      I have what I thought was a simply form that opens a popup (another form)
      whenever an event happens. My main form, Form A, has an instance of Form B
      created on it. I set a bunch of parameters and then call a method on Form B
      to show itself and do a few more things. I can get the event to fire correct
      by pressing a button; everything was working great.
      >
      However, I'm now trying to add in a class file that will check an XML stream
      over and over. If that xml file changes, I need the popup from above to open
      up to alert the user that something has changed. I fire off a thread, but of
      course I can't open the popup from the thread due to the cross-thread error.
      >
      So basically, I have Form A (the main form), which calls Form B to open
      (Form A also sets some parameters on the 2nd form). I wish to access the
      instance of Form B that is running on Form A from Class C. I've looked in to
      delegates and invoking, but I guess I'm just totally lost about what goes
      where. I've also tried creating a worker class and just open up Form B
      directly from Class C, but that doesn't work very well and it's not the ideal
      solution anyway.
      >
      Any tips? I've googled quite a bit, but I'm still scratching my head.
      >
      Frij

        Comment

        • Ciaran O''Donnell
          #3
          RE: Threading problem

          You should use a filesystemwatch er to raise an event when the file changes.
          This is windows notifying you when the file is written. It saves having to
          read the file over and over and raises the event on the UI thread so no need
          to Invoke.

          Ciaran O'Donnell

          "Frijoles" wrote:
          Figures that right after posting this, I would get it working correctly. :) I
          ended up calling invoke on the main form, which seems to be working exactly
          as I need it to.
          >
          >
          "Frijoles" wrote:
          >
          Hello, hopefully I can describe this probably correctly.

          I have what I thought was a simply form that opens a popup (another form)
          whenever an event happens. My main form, Form A, has an instance of Form B
          created on it. I set a bunch of parameters and then call a method on Form B
          to show itself and do a few more things. I can get the event to fire correct
          by pressing a button; everything was working great.

          However, I'm now trying to add in a class file that will check an XML stream
          over and over. If that xml file changes, I need the popup from above to open
          up to alert the user that something has changed. I fire off a thread, but of
          course I can't open the popup from the thread due to the cross-thread error.

          So basically, I have Form A (the main form), which calls Form B to open
          (Form A also sets some parameters on the 2nd form). I wish to access the
          instance of Form B that is running on Form A from Class C. I've looked in to
          delegates and invoking, but I guess I'm just totally lost about what goes
          where. I've also tried creating a worker class and just open up Form B
          directly from Class C, but that doesn't work very well and it's not the ideal
          solution anyway.

          Any tips? I've googled quite a bit, but I'm still scratching my head.

          Frij

            Comment

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