Question

I am new to WP7 coding.
I am looking for sample code or guiding on the following task:

I had 3 html pages on remote server and I want to download the contents of each of the page and post it to 3 different panorama page (show as a textblock).

I had written 3 set of webclient to load the html page; it can be shown as where it suppose to be. My issue facing is, when/during the downloading, the UI thread is “freez” and unresponsive.

Can anyone guide me / show me the sample code that I can put the thread to background and once it finish, and shown in the UI?

This is the code that I use to download the HTML page.

private async void GetNewsIndex(string theN)
    {
        string newsURI = newsURL + theN;
        string fileName = theN + "-temp.html";
        string folderName = "news";

        prgBar01.Visibility = System.Windows.Visibility.Visible;

        try
        {
            Task<string> contentDataDownloaded = new WebClient().DownloadStringTaskAsync(new Uri(newsURI));

            string response = await contentDataDownloaded;

            WriteTempFile(theN, response.ToString());

            string contentData = ProcessDataToXMLNews(fileName, folderName);

            WritenewsIndexXMLFile(newsIndexURI, folderName, contentData);

            DisplayNewsIndex();

        }
        catch
        {
            //
        }
    }

I’d modified the above code as per suggestion by Sinh Pham, and it work perfectly as it expected. But, Since I need to run 3 instant of it to download the page from different souce at he same time; the code break. Any idea?

Answer 1

Are you sure the UI freezes when downloading and not when processing the data? From your code it seems like you’re only doing

WriteTempFile(theN, response.ToString());

string contentData = ProcessDataToXMLNews(fileName, folderName);

WritenewsIndexXMLFile(newsIndexURI, folderName, contentData);

DisplayNewsIndex();

on the UI thread. Try wrap them in a BackgroundWorker instead.

Edit: something like this:

Edit2: since your DisplayNewsIndex() function cause changes in the UI, it must be executed on the UI thread.

var bw = new BackgroundWorker();
bw.DoWork += delegate {
    WriteTempFile(theN, response.ToString());
    string contentData = ProcessDataToXMLNews(fileName, folderName);
    WritenewsIndexXMLFile(newsIndexURI, folderName, contentData);
    Deployment.Current.Dispatcher.BeginInvoke(() => {
        DisplayNewsIndex();
    });
};
bw.RunWorkerAsync();