I know how to override back button inside a page:
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
//Do your work here
base.OnBackKeyPress(e);
}
But the problem: I use Inneractive ad service. when I call InneractiveAd.DisplayAd() it shows a new page of its own which doesn't support back button. when it navigate to this page its uri is like this:
/Inneractive.Ad;component/InneractiveFullScreenPage.xaml
The question: is it possible to override back button of that page to navigate back when user presses back?
In HandleBackKeyPress you usually intercept BackKeyPress event, so you would set e.Cancel = true to prevent standard BackKey navigation. To simulate standard navigation you would do something like:
void HookUpBackKeyPress(PhoneApplicationPage page)
{
page.BackKeyPress += HandleBackKeyPress;
}
void HandleBackKeyPress(object sender, CancelEventArgs e)
{
page.NavigationService.GoBack();
}
The problem is to get the reference to the navigated page. The following code will work only after you completely Navigated to the new Page and it might not work when immediately after NavigationService.Navigate(..)
var frame = (PhoneApplicationFrame)Application.Current.RootVisual;
page = (PhoneApplicationPage)frame.Content;
Related
I have an application in which user logins. Now I want that user can't go back to the menu after he presses the logout button.
This is my logout method
public async void OnLogoutButtonClicked(object sender, EventArgs e)
{
App.AuthenticationClient.UserTokenCache.Clear(Constants.ApplicationID);
await Navigation.PushAsync(new LoginPage());
}
So after logout button is clicked it pushes the user to login page.
I'm able to disable the back button using this in login page
protected override bool OnBackButtonPressed()
{
return false;
}
But it makes my app feel not responsive, instead, I want that when the back button is pressed my app should close the application.
I tried this
protected override bool OnBackButtonPressed()
{
return exit();
//
// exit()
}
but it returns boolean, what should I do to make it work?
When the user logs out, you generally don't want to push a new page on the existing navigation stack. The current navigation stack is not longer applicable, so should be discarded, much like how you clear the UserTokenCache.
So your logout method should be more like:
public async void OnLogoutButtonClicked(object sender, EventArgs e)
{
App.AuthenticationClient.UserTokenCache.Clear(Constants.ApplicationID);
Application.Current.MainPage = new LoginPage();
}
Basically, create the new LoginPage and set up a new MainPage, just as though the app were starting and first presenting the user with a LoginPage.
If you do that, then the back button can't get back to the menu, because that whole navigation stack is gone.
I made a WebBrowser and it works except the back button after pressing the back button the app closes and does not go back one in history. How can I solve the problem? I found solutions in the internet but they don't seem to work.
public MainPage()
{
this.InitializeComponent();
this.webBrowser.Navigate(new Uri("http://www.google.com", UriKind.Absolute));
this.webBrowser.LoadCompleted += webBrowser_LoadCompleted;
this.webBrowser.NavigationFailed += webBrowser_NavigationFailed;
this.webBrowser.IsScriptEnabled = true;
}
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
webBrowser.InvokeScript("eval", "history.go(-1)" );
}
P. S.:that is not the whole script but i think the rest is unneccesary if not tell me :)
P. P. S.:I'm new to Windows Phone programing.
Web browser is just a control inside the page and pressing the device back button navigates back to the previous page or exits the app if it has only one page. So, you would need to stop page navigation on back key press something like this.
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
e.Cancel=true;
}
This prevents a backnavigation
Now rest is to go to the previous page which can be done by
webBrowser.InvokeScript("eval", "history.go(-1)" );
so the event becomes
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
e.Cancel=true;
webBrowser.InvokeScript("eval", "history.go(-1)" );
}
Try to do:
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
WB1.InvokeScript("eval", "history.go(-1)");
e.Cancel = true;
}
When you override OnBackKeyPress, and you don't perform e.Cancel = true; it will do your code, but will also do what normal BackButton does - NavigateBack, Exit App and so on. But you must remember to leave the User an ability to exit your App or Navigate Back, so it will be more suitable to check some conditions (e.g. your webbrowser history is not null) and then do e.Canel, otherwise Exit the App.
To exit the app when you are in the root (so you can approve the cerfitication requirements), and also go back in navigation until you are in the root, try with this
protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
if (MiniBrowser.CanGoBack){
e.Cancel = true;
MiniBrowser.InvokeScript("eval", "history.go(-1)");
}
}
In my app, I have a page where I navigate from the MainPage.xaml. A CameraCaptureTask is launched from that page.
I would like to know, on page loading, how can I know if I have navigated from MainPage.xaml, or it came back from CameraCaptureTask.
Using the NavigationService.BackStack.FirstOrDefault() doesn't help, because, as expected, it returns the MainPage.xaml.
I'd like something like:
protected override void OnNavigatedTo(NavigationEventArgs e)
{
if (/*Navigated-from-MainPage-but-not-from-CameraCaptureTask*/)
{
// Do Something
}
}
You can accomplish this in one of two ways. The first is to listen to the Completed event of the CameraCaptureTask
CameraCaptureTask task = new CameraCaptureTask();
task.Completed += new EventHandler<PhotoResult>(OnCaptureTaskCompleted);
task.Show();
...
void OnCaptureTaskCompleted(object sender, PhotoResult e)
{
// Navigated back or took a picture
}
The second way is to check the NavigationMode of the NavigationEventArgs. If the value is Back, then you know you navigated back from the CameraCaptureTask (assuming that this page does not navigate to any other pages)
protected override void OnNavigatedTo(NavigationEventArgs e)
{
if (e.NavigationMode == NavigationMode.Back)
{
// came back from CameraCaptureTask
}
}
how to determine when navigationwindow back button is pressed and trap that event to something extra. I am thinking of managing the page state.
Add a handler to either NavigationWindow.Navigating or NavigationService.Navigating. In your handler:
void NavigationService_Navigating(object sender, NavigatingCancelEventArgs e)
{
if (e.NavigationMode == NavigationMode.Back) {
e.Cancel = true;
// TODO: whatever state management you're going to do
}
}
P.s. You will need to register the navigation service. In my code it didn't work on the page constructor because the navigation service was still null. So I added Loaded="page_Loaded" to the XAML page tag and assigned it there:
bool _navigationServiceAssigned = false;
private void page_Loaded(object sender, RoutedEventArgs e)
{
if (_navigationServiceAssigned == false)
{
NavigationService.Navigating += NavigationService_Navigating;
_navigationServiceAssigned = true;
}
}
The NavigatingCancelEventArgs contains all of the information about the navigation request you'll need to manage page state.
The NavigationService provides a number of events you can subscribe to, if you want to control the navigation process:
Navigating, when the frame is about to navigate. Set Cancel to true
to stop.
Navigated, when navigation has finished but before it is
rendered
NavigationFailed, when something goes wrong
NavigationProgress, when chunks of a remote navigation call are being
downloaded.
NavigationStopped, when the StopLoading method is called
or a new Navigate request is made during downloading
LoadCompleted, when the page has been rendered
I am writting this method to track if changes occured on a page so the user can trigger a reload of a dependent system. So this as you can see triggers when the user is trying to navigate away from the page. If the e.Cancel is not there the behavior seems fine the async web-service call happen as expected but I am not sure what is really happening in the back.
The reload button click method triggers a chain of event that usually update the display but since the user has navigated away from the page the components are no longer visible. Can this cause problems to the application? Should I be forcing the user to remain on the same page just to prevent possible callback problems?
protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
base.OnNavigatingFrom(e);
if (hasDataBeenModified)
{
if (System.Windows.Browser.HtmlPage.Window.Confirm("You have not reloaded the policies\nDo you want to do it now?"))
{
//e.Cancel = true;
ReloadButton_Click(null, null);
}
}
}
Instead of using OnNavigatingFrom, use OnBackKeyPress
protected override void OnBackKeyPress(CancelEventArgs e)
{
if (hasDataBeenModified)
{
if (System.Windows.Browser.HtmlPage.Window.Confirm("You have not reloaded the policies\nDo you want to do it now?"))
{
e.Cancel = true;
ReloadButton_Click(null, null);
}
}
}