C＃如何使用多个对象的事件处理程序？

Question

Apologies as I have never used event handlers before, and don't know how to phrase the question yet. I understand the concept of them.

I am working on a video file processing tool which processes videos frame by frame. The user selects a group of videos, and the application will run this code to loop through them and and trigger processing on each one:

foreach (string[] item in fileList)
{
    FileVideoSource videoSource;
    videoSource = new FileVideoSource(item[1]);
    videoSource.NewFrame += new NewFrameEventHandler(video_NewFrame);
    videoSource.Start();
}

This directs each new frame that is processed to the event handler called "video_NewFrame".

The event handler looks like this:

private void video_NewFrame(object sender, NewFrameEventArgs eventArgs) {
    try {
        this.Invoke((MethodInvoker) delegate {
            // get new frame
            Bitmap bitmap = eventArgs.Frame;

            //Process frame code...

            pictureBox1.Image = bitmap;
            Application.DoEvents();
        });
    } catch {
        Application.Exit();
    }
}

Now there will be multiple files in the fileList which need to be processed. (I plan to use threading in the future).

Currently this code will process all of the frames together, rather than separately for each video. How can I separate the objects for the event handler to process the objects individually?

Answer 1

What you should do is create a class whose constructor receives the string.. all the class does is what the body of the loop does, but registers his instance method for handling the event.. you just need to instantiate the classes in the loop body and keep them in scope for as long as necessary.

class VideoProcessor
{
  private FileVideoSource videoSource;

  public VideoProcessor(string fileName)
  {
    videoSource = new FileVideoSource(fileName);        
  }

  public void Start()
  {
    videoSource.NewFrame += video_NewFrame;
    videoSource.Start();
  }

  private void video_NewFrame(object sender, NewFrameEventArgs eventArgs)
  {

  }
}