I am using this binding for this awesome Material Drawer Library by MikePenz.
I have implemented the Navigation Drawer with this library and I have also managed to change the hamburger menu to the back arrow when I go level deep. Now I have some problems to get the back arrow to work correctly. When I click on the back arrow, rather than going back to the previous page, it opens up the navigation drawer.
After looking into the original library, I have identified, the following code is responsible to manage the back arrow button. I would appreciate , if someone can help me a bit to write this listener code in C#.
.withOnDrawerNavigationListener(new Drawer.OnDrawerNavigationListener() {
#Override
public boolean onNavigationClickListener(View clickedView) {
//this method is only called if the Arrow icon is shown. The hamburger is automatically managed by the MaterialDrawer
//if the back arrow is shown. close the activity
AdvancedActivity.this.finish();
//return true if we have consumed the event
return true;
}
})
Here is the binding libray that I use : MaterialDrawer-Xamarin
And this is the link to the original Library : MaterialDrawer
Try something like this:
var result = new DrawerBuilder()
.WithActivity(this)
.AddDrawerItems(
//Add some items here
new DividerDrawerItem()
)
.WithOnDrawerNavigationListener(this);
and implement Drawer.IOnDrawerNavigationListener in your activity like this:
public bool OnNavigationClickListener(View clickedView)
{
this.Finish();
return true;
}
Related
I have a Xamarin.Forms application which uses a TabbedPage, let's call it T, T consists of 3 ContentPage children A, B and C. Since the usere has the possibility to edit some data on tab B, I want to notify user before leaving tab in order to allow him to cancel the navigation change and save changes first or to discard changes and leave. So far I have managed to override OnBackButtonPressed() method and the navigation bar back button (which would exit TabbedPage). However I quickly noticed that I am still loosing changes when switching between tabs. I would like to override the click on new tab, so I could first present user with the leaving dialog and the skip the change or continue with it. What would be the best way to do this? I am currently working only on Android platform, so solutions on the platform level are also acceptible.
Thank you for your suggestions and feedback :)
I do not think there is an easy way to do this ,
you can use OnDissappearing and OnAppearing for the pages, that is as easy as it gets .
However I think you are using the wrong design.
Having tabs are ment to make it easier to navigate between pages, if you are going to notify the user when changing the tabs then it would be annoying . If I were you i would save the data for each page locally. so when you get back to the page you will have the data anyway.
So in the end I followed the advice of Ahmad and implemented the persisting of data on individual tabs so they are not lost when tabs are switched. (I no longer refresh input fields from data from model when OnAppearing is called).
But in order to know if there are some unsaved changes on my ChildB page, I had to implement the following procedures:
I created the method HandleExit on my ChildB page, which checks for unsaved changes in fields (at least one value in input fields is different from the ones in stored model) and the either prompts the user that there are unsaved changes (if there are some) or pops the navigation stack if there are no changes.
private async Task HandleExit()
{
if(HasUnsavedChanges())
{
var action = await DisplayAlert("Alert", "There are unsaved changes, do you want to discard them?", "Discard changes", "Cancel");
if(!action)
{
return;
}
}
await Navigation.PopAsync();
}
Since there are two ways on how user can return from Tabbed page (pressing the back button on device or pressing the back button in navigation bar, I had to:
A: override the back button method on my ChildB page, so it calls the HandleExit method. But since Navigation.PopAsync() needs to be called on UI thread, I had to explicitly execute the method on UI thread as written below:
protected override bool OnBackButtonPressed()
{
Device.BeginInvokeOnMainThread(new Action(async () =>
{
await HandleExit();
}));
return true;
}
B: Since there is no way to intercept the navigation bar back button on the ContentPage, I had to intercept the event on the platform level (Android) and then pass the event to the ContentPage if necessary via MessagingCenter. So first we need to intercept the event, when navigation bar button is pressed in one of the child pages and send the event via MessagingCenter. We can do that but adding the following method in our MainActivity.cs class:
public override bool OnOptionsItemSelected(IMenuItem item)
{
// check if the current item id
// is equals to the back button id
if (item.ItemId == 16908332)
{
// retrieve the current xamarin forms page instance
var currentpage = Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.LastOrDefault();
var name = currentpage.GetType().Name;
if(name == "ChildA" || name == "ChildB" || name == "ChildC")
{
MessagingCenter.Send("1", "NavigationBack");
return false;
}
}
return base.OnOptionsItemSelected(item);
}
Now whenever we will press the navigation bar back button in one of the child pages (ChildA, ChildB, ChildC) nothing will happen. But the button will work as before on the rest of the pages. For the second part of solution we need to handle the message from MessagingCenter, so we need to subscribe to it in our ChildB page. We can subsribe to the message topic in OnAppearing method as follows:
MessagingCenter.Subscribe<string>(this, "NavigationBack", async (arg) => {
await HandleExit();
});
Be careful to unsubscribe to the topic in OnDisappearing() otherwise strange things could happen, since there will be references left to your ContentPage even if you pop it from your navigation stack.
Now that we have handled both requests for back navigation in our ChildB page, we also need to handle them in all of remaining child pages (ChildA, ChildC), so they will know if there are unsaved changes in ChildB page, even if it is currently not selected. So the solution is again compraised of handling the device back button, and navigation bar back button, but first we heed a way to check if ChildB has unsaved changes when we are on one of the remaining pages, so we again write HandleExit method but this time it is as follows:
private async Task HandleExit()
{
var root = (TabbedPage)this.Parent;
var editPage = root.Children.Where(x => x.GetType() == typeof(ChildB)).FirstOrDefault();
if(editPage != null)
{
var casted = editPage as ChildB;
if (casted.HasUnsavedChanges())
{
var action = await DisplayAlert("Alert", "There are unsaved changes, do you want to discard them?", "Discard changes", "Cancel");
if (!action)
{
return;
}
}
}
await Navigation.PopAsync();
}
The only thing that remains now is to handle both navigation back events inside remaing child pages. The code for them is the same as in the actual ChildB page.
A: Handling the device back button.
protected override bool OnBackButtonPressed()
{
Device.BeginInvokeOnMainThread(new Action(async () =>
{
await HandleExit();
}));
return true;
}
B: Subscribing to topic from MessagingCenter
MessagingCenter.Subscribe<string>(this, "NavigationBack", async (arg) => {
await HandleExit();
});
If everthing has been done correctly, we should now be prompted with a dialog on any of the child pages if there are unsaved changes on the ChildB page. I hope this will help somebody in the future :)
I am developing an iPad app using Xamarin.Forms.
I would like my settingspage to be modal so it lay over the previous page like a popup.
I have been trying all solutions I could find and most of them seems to recommend me to call this from a button:
await Navigation.PushModalAsync(ModalSettingsPage);
What happens when I use it is that my settingspage comes in from below as a modal page but not as a popup, it covers the entire screen.
This is my current code:
//Setup button (action bar)
ToolbarItems.Add(new ToolbarItem
{
// Text = "Setup",
Icon = "settings1.png",
Order = ToolbarItemOrder.Default,
Command = new Command(() => Navigation.PushModalAsync(new ModalSettingsPage())) //Action to perfome on click , open modal view
});
Also, does anyone now if there is any good way to positions the ToolbarItems? I have two items and would like each one to be positioned at each side, but by default they are both positioned to the right.
With the evolution of Forms (currently 4.5.0), it has now become simple to push a modalpage which is not fullscreen. Use the following in your code-behind of your xaml contentpage:
using Xamarin.Forms;
using Xamarin.Forms.PlatformConfiguration;
using Xamarin.Forms.PlatformConfiguration.iOSSpecific;
namespace YourAppWithAModalPage
{
public class ModalPage : ContentPage
{
public ModalPage()
{
// iOS Solution for a ModalPage (popup) which is not fullscreen
On<iOS>().SetModalPresentationStyle(UIModalPresentationStyle.FormSheet);
}
}
}
There is nothing pre-made in Forms to give you a popup like I think you want. Instead, you would have to create this or use a third-party solution. For example, here is a "popup" implementation that might work for you.
Can we override navigation back button pressed in Xamarin.forms?
I have one navigation back button and the one save button in navigation bar.Save button hits the web service and saves in asynchronous way. While saving although i used progressing bar, navigation back button can be pressed and hence the app crashes due to index out of range exception on navigation stack.I tried using OnDisappearing() , did not work. I wanna cancel the PopUpAsync(),if the save is not done completely, but failed to achieve that. Is there any solution for this scenario? Can we override the navigation back button press event using any custom renderer ?
For controlling the back button to do what I want, I used this method in Xamarin:
public override bool OnKeyDown(Keycode HWkeyCode, KeyEvent e)
{
if (HWkeyCode == Keycode.Back)
{
StartActivity(typeof(FrontPageActivity));
return true;
}
return false;
}
I have an application, the main page contains few functions. To explain in detail - I have save, color palette button in my main page. When any of these buttons are clicked, save pop up or color palette appears. How to handle back button of the device, when color palette or save pop up is opened. When back button is pressed at these scenario it should just make them invisible and stay on the main page. When nothing is being performed in the main page, then it should come out of the app. I tried to make their visibility collapsed on back button press. But it still is coming out of the application.
Please, guide me in this. Thanks in advance.
Override PhoneApplicationPage.OnBackKeyPress and then set CancelEventArgs.Cancel to true if you want to stop it from actually going back.
protected override void OnBackKeyPress(CancelEventArgs args)
{
if (PanelIsShowing)
{
HidePanel();
args.Cancel = true;
}
}
The back button behaves as is intended by Microsoft.
If you change its behavior you risk your application not being certified for the Marketplace.
If you want the back button to close the popups, turn the popups into pages so the back button navigates back to the main page..
You need to use
protected override void OnBackKeyPress(CancelEventArgs e)
{
if (_popup.IsOpen)
{
_popup.IsOpen= false;
e.Cancel = true;
}
else
{
base.OnBackKeyPress(e);
}
}
That should do the trick.
I'm new to creating Silverlight applications. I have inherited a code-base that I've been told is using Prism. Based upon what I've seen in the code-base, this looks to be true. My problem is, I am just trying to open a dialog window and close a dialog window.
To open the dialog window, I'm using the following:
UserControl myDialog = new MyDialog();
IRegion region = myRegionManager.Regions["DIALOG_AREA"];
IRegionManager popupRegionManager = region.Add(myDialog, null, true);
region.Activate(myDialog);
The dialog I have designed appears. It has two buttons: "OK" and "Cancel". When a user clicks on of these dialogs, I want to close the dialog. My problem is, I have no idea how to do this. Because the dialog is not a ChildWindow, I cannot call this.Close(). But, when I change MyDialog to a ChildWindow, it is wrapped in some custom window chrome that i can't figure out how to get rid of.
How do I close a dialog in Prism? Thank you!
Instead of putting in a different region, you should make your ViewModel call a service where you call your dialog window.
public MainPageViewModel(IMainPage view,
ILoginBox loginBox )
: base(view)
{
this.view = view;
this.loginBox = loginBox;
}
public interface ILoginBox
{
void Show();
}
remember to use the IOC container and declare on your ModuleClass:
protected override void RegierTypes()
{
base.Container.RegisterType<ILoginBox , LoginBox>();
}
I hope it helps.
If you are still looking for an example, check:
another Stackoverflow sample