Back button on Windows Phone 8

Question

I am having trouble getting the back hardware button to do what I would like it to do for the Windows Phone 8. The app is strictly just webview, so as of now when a back (hardware) button is clicked it closes the app. How can I work around this so it goes to the previous webpage or goes back to the index or something on those lines?

Thanks

This is what I currently have in the MainPage.xaml.cs file

namespace AvoidDiabetes
{
public partial class MainPage : PhoneApplicationPage
{
    // Url of Home page
    private string MainUri = "/Html/index.html";
    private Stack<Uri> _history = new Stack<Uri>();
    private Uri _current = null;

    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }

    private void Browser_Loaded(object sender, RoutedEventArgs e)
    {
        // Add your URL here
        Browser.Navigate(new Uri(MainUri, UriKind.Relative));
        Browser.IsScriptEnabled = true;
    }

    // Navigates back in the web browser's navigation stack, not the applications.
    private void BackApplicationBar_Click(object sender, EventArgs e)
    {
        Browser.GoBack();
    }

    // Navigates forward in the web browser's navigation stack, not the applications.
    private void ForwardApplicationBar_Click(object sender, EventArgs e)
    {
        Browser.GoForward();
    }

    // Navigates to the initial "home" page.
    private void HomeMenuItem_Click(object sender, EventArgs e)
    {
        Browser.Navigate(new Uri(MainUri, UriKind.Relative));


    }

    // Handle navigation failures.
    private void Browser_NavigationFailed(object sender, System.Windows.Navigation.NavigationFailedEventArgs e)
    {
        MessageBox.Show("Navigation to this page failed, check your internet connection");
    }



    protected override void OnBackKeyPress(CancelEventArgs e)
    {
        base.OnBackKeyPress(e);


        if (_history.Count == 0)
        {
            // No history, allow the back button
            // Or do whatever you need to do, like navigate the application page
            return;
        }
        // Otherwise, if this isn't the first navigation, push the current
        else
        {
            Browser.GoBack();
        }




    }

    private async void WebBrowser_Navigated(object sender, NavigationEventArgs e)
    {
        // If we navigated back, pop the last entry
        if (_history.Count > 0 && _history.Peek() == e.Uri)
        {
            _history.Pop();
        }
        // Otherwise, if this isn't the first navigation, push the current
        else if (_current != null)
        {
            _history.Push(_current);
        }

        // The current page is now the one we've navigated to
        _current = e.Uri;
    }

}

}

Solution 1

You need to override OnBackKeyPress in your application's page and handle navigating the WebBrowser control back to the previous page.

Assuming you're using C#, here's roughly how you could do it (hook up WebBrowser_Navigated to your WebBrowser's Navigated event):

private Stack<Uri> _history = new Stack<Uri>();
private Uri _current = null;

protected override void OnBackKeyPress(CancelEventArgs e)
{
    base.OnBackKeyPress(e);

    if (_history.Count == 0)
    {
        // No history, allow the back button
        // Or do whatever you need to do, like navigate the application page
        return;
    }

    // Cancel the back button press
    e.Cancel = true;

    // Navigate to the last page
    Browser.Navigate(_history.Peek());
}

private async void WebBrowser_Navigated(object sender, NavigationEventArgs e)
{
    // If we navigated back, pop the last entry
    if (_history.Count > 0 && _history.Peek() == e.Uri)
    {
        _history.Pop();
    }
    // Otherwise, if this isn't the first navigation, push the current
    else if (_current != null)
    {
        _history.Push(_current);
    }

    // The current page is now the one we've navigated to
    _current = e.Uri;
}

Solution 2

this worked with me, you can check if browser.CanGoBack() if true the go back else just return

   protected override void OnBackKeyPress(CancelEventArgs e) {
        base.OnBackKeyPress(e);


        if (browser.CanGoBack)
        {
            e.Cancel = true;
            browser.GoBack();
        }
        else {
            return;
        }
    }

Comments

[Richard J. Ross III]

Awesome. Ill try this in my monogame app tomorrow and get back to you!

[Richard J. Ross III]

Thanks. Worked great. Have a bounty (in 4 hours), my pleasure :)

[Admin]

Thanks so much, but I am sorry, but I am pretty new in programming and a little lost. When I added that into my web browswer's navigated page I was having trouble with the CancelEventArgs event being underlined as an error. Any suggestions?

[Peter Huene]

Are you "using System.ComponentModel;" in the source file?

[Peter Huene]

At the top of the file you should see other using statements. If that one is missing, you needed to add it. It informs the compiler to search that namespace to resolve the CancelEventArgs type.

[Admin]

not too sure how to add the code that I have into the comment to this, but I just added it up to the top in the original question. Any ideas what I should do from it?

[Admin]

okay I figured that part out, and I got the code to compile with no errors, but when I press the back button it is still closing the application. Maybe I added it at the wrong spot?

[Peter Huene]

See the comment I added in OnBackKeyPress. It will currently back out of the page if there is no history (I.e. nothing to go back to in the browser). If you want it to do nothing, set e.Cancel to true there.

[Admin]

hmm... yeah still not working for me, even when I navigate to many different pages, still gets out of the page. Thanks anyways

[Admin]

damn, never mind, it's not working. It always thinks _history.Count = 0. It never registers more then that even when the user navigates from say index.html to 1.html

[Peter Huene]

If you set a breakpoint on WebBrowser_Navigated, does it get hit (I assume you've hooked up the method to the Navigated event)?

[Admin]

I may be putting it in the wrong section, I have put the code that I have up top.

[Peter Huene]

Are you subscribing to the Navigated event in the XAML then? If not, you'll need to hook up the event after the InitializeComponent call.