I am trying to create a custom control for webview, i am trying to get a checkbox inside a webview Reason :- we have a bunch of text to be displayed and unless the user reaches the end of the scroll he cannot move to the next page and at the end of the scroll there is a checkbox where user has to check the the checkbox and then he can process. here i have tried putting the checkbox and webview inside the stacklayout but the issue is webview have its own scroll bar and and stacklayout scroll bar does not work when a user try to scroll as the webview scroller scrolls out also when i try to close the Webview Page with back button the webview gets close and not the page
i am not sure what approach should i apply here.
i am getting my html data from my webapi.
anyone with some solution would be appreciable
here is my custom renderer which i have wrote but the piece missing here is how can i add another xamarin control inside this
public class CustomPdfViewRenderer : WebViewRenderer
{
public CustomPdfViewRenderer(Context context) : base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (Control != null)
{
Control.Settings.BuiltInZoomControls = true;
Control.Settings.DisplayZoomControls = false;
Control.Settings.LoadWithOverviewMode = true;
Control.Settings.UseWideViewPort = true;
}
}
}
You can try the following approach:
Add checkbox to HTML
When the user check checkbox call some JavaScript function
When JavaScript function is called, call C# function (Xamarin) which will enable the user to process to the next page (or some other Xamarin side stuff)
Here is how you can call C# function from JavaScript :HybridWebView
Related
We have designed a custom popup with Content View, which will be invoked in a content page. When clicked on hardware back custom popup is getting closed, because Content View as no property to hand hardware back button Pressed. OnBackButtonPressed() is used only for Content Page. Can I get any solution to handle hardware back for content view to stop popup from closing.
To manage hardware back button you must override OnBackPressed() method in MainActivity class, in android project. In your popup you may have some property to check if can be closed and then check it from MainActivity class.
public override void OnBackPressed()
{
if (CheckIfCanBePressedMethod())
{
// back pressed will be ignored
// code here
}
else
{
// default behavior
base.OnBackPressed();
}
}
Set the flag on Contentpage when you open popup make the bool as true.
bool isShowPopup = false;
public override void OnBackPressed()
{
if (!isShowPopup)
{
base.OnBackPressed();
}
}
Is there any way to detect the press of the back button of the Navigation Page in Xamarin forms?
You can override your navigation page "OnBackButtonPressed" method:
protected override bool OnBackButtonPressed()
{
Device.BeginInvokeOnMainThread(async () =>
{
if (await DisplayAlert("Exit?", "Are you sure you want to exit from this page?", "Yes", "No"))
{
base.OnBackButtonPressed();
await App.Navigation.PopAsync();
}
});
return true;
}
If you are using the shell, you can override the Shell's OnNavigating event:
void OnNavigating(object sender, ShellNavigatingEventArgs e)
{
// Cancel back navigation if data is unsaved
if (e.Source == ShellNavigationSource.Pop && !dataSaved)
{
e.Cancel();
}
}
Update:
OnBackButtonPressed event will get fired ONLY on Android when user press the Hardware back button.
Seems like you are more interested to implement when any page get disappeared you want to do something!
In that case:
You have the page's two methods -
protected override void OnAppearing()
{
base.OnAppearing();
Console.WriteLine("Hey, Im coming to your screen");
}
protected override void OnDisappearing()
{
base.OnDisappearing();
Console.WriteLine("Hey, Im going from your screen");
}
You can override those 2 methods on any page to track when they appear and disappear.
Recent updates to Xamarin forms mean you can now do this in an application made with Shell Navigation for navigation back arrow on both platforms.
Use the Shell.SetBackButtonBehavior method, for example running this code in the constructor of your page object will allow the back navigation to take place only when the bound viewmodel is not busy:
Shell.SetBackButtonBehavior(this, new BackButtonBehavior
{
Command = new Command(async() =>
{
if (ViewModel.IsNotBusy)
{
await Shell.Current.Navigation.PopAsync();
}
})
});
In the body of the Command you can do whatever you need to do when you are intercepting the click of the back button.
Note that this will affect only the navigation back button, not the Android hardware back button - that will need handling separately as per the answers above. You could write a shared method called from both the back button pressed override and the command on shell back button behaviour places to share the logic.
You must override native navigationbar button behavior with custom renderer. OnBackButtonPressed triggers only physical device button. You can read good article how to achive this here
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 2 pages in my Xamarin Forms app. My first page has 4 icons in the toolbar. My second page is a login page and has a tick and a cross in the toolbar.
I can't get the login page to show any icons unless I make it a navigation page. I also have to clear ToolBarItems on the first page before calling PushAsync() otherwise it complains there are too many toolbar items.
If I call PopAsync() on the login page it does not return to the first page. I'm guessing this is due to their being 2 navigation pages. I also tried PopToRootAsync().The back button works however.
My question is - how do I show different toolbar icons on 2 different pages in a way that allows navigation to work?
I'm testing this on Windows Phone 8.0
Here is the code calling the login page:
private async void ShowLoginPage()
{
ToolbarItems.Clear();
var page = new NavigationPage(new LoginPage());
await Navigation.PushAsync(page);
}
and here is the code to return to the first page:
private void Cancel()
{
Navigation.PopToRootAsync();
}
I'm running Xamarin.Forms v1.2.2.6243
One thing you could try is to keep your Login Page inside of a NavigationPage, and then instead of running PopAsync() within the Login Page after they have logged in successfully, simply replace the MainPage with your old Navigation page:
In your App class:
public NavigationPage AppNavPage = new NavigationPage(new FirstPage());
public App() {
MainPage = AppNavPage;
}
In your FirstPage:
private async void ShowLoginPage() {
ToolbarItems.Clear();
var page = new NavigationPage(new LoginPage());
await Navigation.PushAsync(page);
}
In Login Page:
private async void OnCreateClicked(object sender, EventArgs e) {
bool loginInfoIsGood = CheckLoginInfo(); //Check their login info
if(loginInfoIsGood) {
Application.Current.MainPage = App.AppNavPage;
}
}
Otherwise, I have also done a custom renderer for the NavigationRenderer on iOS to insert toolbar items onto the right side of the Navigation Bar and have overridden some Menu related stuff on Android to change the icon text/colors.
One option that you have, and one that I implemented in my own app, is a custom renderer that removes the navigation header from the app and then you could build your own custom header. With this approach, you do lose some of the native feel of the app, and you have to implement much of the transitional functionality your self. However, it gives you alot more control over the look.
CustomRenderer that removes the navigationBar:
//add using statements
// add all view here that need this custom header, might be able to build a
//base page that others inherit from, so that this will work on all pages.
[assembly: ExportRenderer(typeof(yourView), typeof(HeaderRenderer))]
class HeaderRenderer : PageRenderer
{
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
this.NavigationController.SetNavigationBarHidden(true, true);
}
}
After this you can build a header view that can be placed on the top of every page (I am using xaml) so I don't know if it is relevant in you application.
Edit: You might need to change this renderer for differnt page types.