In my windows phone app sometimes it takes me two page backward although I pressed hardware back button just once.
To handle the back button I used following code snippet:
private void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
e.Handled = true;
if (Frame.CanGoBack)
Frame.GoBack();
}
And in OnNavigatedTo() method I added following line:
Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
How can I make sure that one back button press will take just one page backward?
Add following line into the OnNavigatedFrom method:
Windows.Phone.UI.Input.HardwareButtons.BackPressed -= HardwareButtons_BackPressed;
In case the OnNavifatedFrom doesn't exist in your partial class of the XAML page, create it like bellow:
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
Windows.Phone.UI.Input.HardwareButtons.BackPressed -= HardwareButtons_BackPressed;
}
Related
In my Xaml Page I've got a Frame.
I'm trying to have a backButton event to just navigate inside frame .
so I tried to use this piece of code
public MainPage(){
this.InitializeComponent();
if(Windows.Foundation.Metadata.ApiInformation.IsTypePresent("Windows.Phone.UI.Input.HardwareButtons")) {
Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
}
}
private void HardwareButtons_BackPressed(object sender,BackPressedEventArgs e) {
if(insideFrame.CanGoBack())insideFrame.GoBack();
else Application.Current.Exit();
}
but In phone after doing HardwareButtons_BackPressed event it close the application.
It seems to running some default back button behavior on MainPage...
How can I fix it? And In Windows10 does they add new events to handle back navigation?
[Update]
Now I found out it's better to Use SystemNavigationManager in Windows 10 instead of Input.HardwareButtons.BackPressed.
SystemNavigationManager currentView = SystemNavigationManager.GetForCurrentView();
Windows 10 (UWP) include SystemNavigationManager in Windows.UI.Core namespace for Navigation purpose only.
Because SystemNavigationManager is part of Windows Universal Platform, So, it's supported by all device family running on Windows 10 including Mobile and PC.
For Single Page
If you just want to handle navigation for single page. Follow the following steps
Step 1. Use namespace Windows.UI.Core
using Windows.UI.Core;
Step 2. Register back request event for current view. Best place for this is main constructor of class after InitializeComponent().
public MainPage()
{
this.InitializeComponent();
//register back request event for current view
SystemNavigationManager.GetForCurrentView().BackRequested += MainPage_BackRequested;
}
Step 3. Handle BackRequested event
private void Food_BackRequested(object sender, BackRequestedEventArgs e)
{
if (Frame.CanGoBack)
{
Frame.GoBack();
e.Handled = true;
}
}
For Complete Application at one place for single rootFrame
Best place for handling all backbutton for all Views is App.xaml.cs
Step 1. Use namespace Windows.UI.Core
using Windows.UI.Core;
Step 2. Register back request event for current view. Best place for this is OnLaunched just before Window.Current.Activate
protected override void OnLaunched(LaunchActivatedEventArgs e)
{
...
SystemNavigationManager.GetForCurrentView().BackRequested += OnBackRequested;
Window.Current.Activate();
}
Step 3. Handle BackRequested event
private void OnBackRequested(object sender, BackRequestedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (rootFrame.CanGoBack)
{
rootFrame.GoBack();
e.Handled = true;
}
}
References- Handle back button pressed in UWP
Hope this is helpful to someone!
You need to tell the system that you handled the backbutton press by setting the Handled property of the BackPressedEventArgs to true.
private void OnHardwareButtonsBackPressed(object sender, BackPressedEventArgs e)
{
// This is the missing line!
e.Handled = true;
// Close the App if you are on the startpage
if (mMainFrame.CurrentSourcePageType == typeof(Startpage))
App.Current.Exit();
// Navigate back
if (mMainFrame.CanGoBack)
{
mMainFrame.GoBack();
}
}
follow these steps:
Add two Global Variables in your page as below.
private NavigationHelper navigationHelper;
private RelayCommand _GoBackCommand;
Then add below code in constructor of specific page.
// below code is to override the back navigation
// hardware back button press event from navigationHelper
_GoBackCommand = new RelayCommand
(
() => this.CheckGoBack(),
() => this.CanCheckGoBack()
);
navigationHelper.GoBackCommand = _GoBackCommand;
// ---------
Then add both those methods we've just declared in constructor.
private bool CanCheckGoBack()
{
// this should be always true to make sure the app handles back buton manually.
return true;
}
private void CheckGoBack()
{
// this will be execute when back button will be pressed
}
ps. - for this you might need to use BasicPage instead of BlankPage while adding new page.
hope this will help..!
Try this.It will work for frame back navigation.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
HardwareButtons.BackPressed += HardwareButtons_BackPressed;
}
void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (Frame.CanGoBack)
{
e.Handled = true;
Frame.GoBack();
}
}
}
I think this is because you add HardwareButtons_BackPressed in your page instead on in app.xaml.cs.
In app.xaml.cs :
public App()
{
this.InitializeComponent();
this.Suspending += this.OnSuspending;
HardwareButtons.BackPressed += HardwareButtons_BackPressed;
}
void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (rootFrame != null && rootFrame.CanGoBack)
{
e.Handled = true;
rootFrame.GoBack();
}
}
Now, back button of your phone will work on any pages.
And then, if you want to add a particular button doing back in any page :
In the particular page (or each pages if you want) :
public void btn_return_Tapped(object sender, TappedRoutedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
if (rootFrame != null && rootFrame.CanGoBack)
{
e.Handled = true;
rootFrame.GoBack();
}
}
Source :
http://windowsapptutorials.com/tips/general-tips/handling-the-back-button-in-a-windows-phone-8-1-app/
I have two pages in my app.One is blankPage and other is basic page. On basic page I want to provide a message if a user press back button like
"Are you sure you want to quit" .If Yes then go back else remain there , this working fine by using this code
HardwareButtons.BackPressed += HardwareButtons_BackPressed;
private async void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
e.Handled = true;
MessageDialog dlg = new MessageDialog("Are you sure you want to quit you will loose all your work ?", "Warning");
dlg.Commands.Add(new UICommand("Yes", new UICommandInvokedHandler(CommandHandler1)));
dlg.Commands.Add(new UICommand("No", new UICommandInvokedHandler(CommandHandler1)));
await dlg.ShowAsync();
}
private void CommandHandler1(IUICommand command)
{
var label = command.Label;
switch (label)
{
case "Yes":
{
this.Frame.Navigate(typeof(MainPage));
break;
}
case "No":
{
break;
}
}
}
But when I am pressing back button on my BlankPage this message also appears there and also appearing in all other basic page if I add more . What mistake am I doing??
You are registering hardware back button in page constructor or page load event and once this event is registered you are not unregistering this event. BackPress is app level. for correctly using this event on your desired page register Back Press event in your OnNavigatedTo override method and unregister this event in OnNavigatedFrom ovrride metho. here is how.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
}
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
Windows.Phone.UI.Input.HardwareButtons.BackPressed -= HardwareButtons_BackPressed;
}
Am trying to submit a webform pragmatically on button1 click. In first attemp ie after launching my webbrowser from visual studio it automatically submit the form but again clicking on button1, webpage loads but submit button is not invoked. While debugging its shows that the line of code executed but no action takes place.
private void button1_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("xxxx");
webBrowser1.DocumentCompleted += webBrowser1_DocumentCompleted;
}
void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
if (webBrowser1.Url.OriginalString.ToString() == "xxxx")
{
if(webBrowser1.ReadyState==WebBrowserReadyState.Complete)
{
HtmlElementCollection doc = webBrowser1.Document.All;
foreach (HtmlElement ele in doc)
{
if (ele.GetAttribute("name").ToString()== "username")
{
ele.SetAttribute("value","xxxx");
}
if (ele.GetAttribute("name").ToString() == "password")
{
ele.SetAttribute("value", "xxxx");
}
if (ele.GetAttribute("classname") == "btn")
{
ele.InvokeMember("click");
}
}
}
}
textBox1.Text = webBrowser1.DocumentText;
}
You only want to setup the DocumentCompleted event for the web browser once. In your code you keep adding to the event chain each time the button is pressed which is not the behaviour you want.
You want something like (pseudo code as haven't got VS with me):
// When the form/parent loads bind the event ONCE here.
public void FormLoads()
{
webBrowser1.DocumentCompleted += webBrowser1_DocumentCompleted;
}
// Just navigate here and the event will still be raised
private void button1_Click(object sender, EventArgs e)
{
webBrowser1.Navigate("xxxx");
}
Its Due to your webBrowser1_DocumentCompleted Event is not working when your click on Button.
Just Create one method
Private Void Submit(); and here put your code which you want to perform on click event and call this method from two location one is at button1_click and another webBrowser1_DocumentCompleted so that your code is run at both events.
I have a popup window in my windows phone 8.1 runtime application.
While back button pressed and popup is opened in a page, the app should stay in the page itself, else it should go back. This is my concept. So, I coded like below:
void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
if (PopupWindow.IsOpen)
{
PopupWindow.IsOpen = false;
e.Handled = true;
}
}
Even if the popup windows is open in the page, the app goes to the previous page. I used the same logic in windows phone silverlight application and that worked.
NOTE: I'm using Basic Page.
What mistake actually I'm doing ?
Check two things:
by default in NavigationHelper, HardwareButtons_BackPressed lacks checking if the event was already handeled, try to improve it:
private void HardwareButtons_BackPressed(object sender, Windows.Phone.UI.Input.BackPressedEventArgs e)
{
// if (this.GoBackCommand.CanExecute(null)) // this is as a default
if (this.GoBackCommand.CanExecute(null) && !e.Handled) // add a check-up
// ... rest of the code
look at your App.xaml.cs file, and in App() there is HardwareButtons_BackPressed subscribed (check if subscribed method also navigates back):
public App()
{
this.InitializeComponent();
this.Suspending += OnSuspending;
// HardwareButtons.BackPressed += HardwareButtons_BackPressed; // this line also could fire Frame.GoBack() (as default project template)
// of course check what is in the above method
}
Also remeber that events are fired in the order you have subscribed them and for example Navigation helper subscribes in Loaded event. If you subscribe after then the navigation will be first. You may subscribe before or maybe use a flag.
I resolve in thi way
protected override void OnNavigatedTo(NavigationEventArgs e)
{
Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
}
protected virtual void HardwareButtons_BackPressed(object sender, Windows.Phone.UI.Input.BackPressedEventArgs e)
{
e.Handled = true;
}
when I navigate to Page1.xaml, I have an empty navidation stack, what I need to add into
protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e){}
to add Page2.xaml into Navigation stack (I need to navidate into Page2.xaml only when I press go back button)
If I understand correctly, you want to navigate to Page2.xaml when the user press the Back button, correct?
You'll have to use the BackKeyPressed event to make that work, like so:
public MainPage()
{
InitializeComponent();
this.BackKeyPress += new EventHandler<System.ComponentModel.CancelEventArgs>(MainPage_BackKeyPress);
}
void MainPage_BackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
{
e.Cancel = true;
Dispatcher.BeginInvoke(() =>
{
NavigationService.Navigate(new Uri("/Page2.xaml", UriKind.Relative));
});
}
But please be advised that changing the default behavior of the Back button may lead to fail app certification!