public void HandleNavigating(ShellNavigatingEventArgs args)
{
if (!args.DeferredEventArgs)
{
Navigating?.Invoke(this, args);
}
else
{
return;
}
}
void Handle_Navigating(object sender, Xamarin.Forms.ShellNavigatingEventArgs e)
{
if ((Device.RuntimePlatform == "iOS") && e.Target.Location.AbsolutePath.IndexOf("carousel") > -1)
{
(App.Current.MainPage as Shell).DisplayAlert(
title: "Not Yet!",
message: "iOS doesn't yet support CarouselView.",
cancel: "Okay"
);
e.Cancel();
}
}
ShellNavigatingEventArgs ProposeNavigation(
ShellNavigationSource source,
ShellNavigationState proposedState,
bool canCancel,
bool isAnimated)
{
if (_accumulateNavigatedEvents)
{
return(null);
}
var navArgs = new ShellNavigatingEventArgs(_shell.CurrentState, proposedState, source, canCancel)
{
Animate = isAnimated
};
HandleNavigating(navArgs);
return(navArgs);
}
public async Task GoToAsync(ShellNavigationParameters shellNavigationParameters)
{
if (shellNavigationParameters.PagePushing != null)
{
Routing.RegisterImplicitPageRoute(shellNavigationParameters.PagePushing);
}
var state = shellNavigationParameters.TargetState ?? new ShellNavigationState(Routing.GetRoute(shellNavigationParameters.PagePushing), false);
bool?animate = shellNavigationParameters.Animated;
bool enableRelativeShellRoutes = shellNavigationParameters.EnableRelativeShellRoutes;
ShellNavigatingEventArgs deferredArgs = shellNavigationParameters.DeferredArgs;
var navigationRequest = ShellUriHandler.GetNavigationRequest(_shell, state.FullLocation, enableRelativeShellRoutes, shellNavigationParameters: shellNavigationParameters);
bool isRelativePopping = ShellUriHandler.IsTargetRelativePop(shellNavigationParameters);
ShellNavigationSource source = CalculateNavigationSource(_shell, _shell.CurrentState, navigationRequest);
// If the deferredArgs are non null that means we are processing a delayed navigation
// so the user has indicated they want to go forward with navigation
// This scenario only comes up from UI iniated navigation (i.e. switching tabs)
if (deferredArgs == null)
{
var navigatingArgs = ProposeNavigation(source, state, _shell.CurrentState != null, animate ?? true);
if (navigatingArgs != null)
{
bool accept = !navigatingArgs.NavigationDelayedOrCancelled;
if (navigatingArgs.DeferredTask != null)
{
accept = await navigatingArgs.DeferredTask;
}
if (!accept)
{
return;
}
}
}
Routing.RegisterImplicitPageRoutes(_shell);
_accumulateNavigatedEvents = true;
var uri = navigationRequest.Request.FullUri;
var queryString = navigationRequest.Query;
var queryData = ParseQueryString(queryString);
ApplyQueryAttributes(_shell, queryData, false, false);
var shellItem = navigationRequest.Request.Item;
var shellSection = navigationRequest.Request.Section;
var currentShellSection = _shell.CurrentItem?.CurrentItem;
var nextActiveSection = shellSection ?? shellItem?.CurrentItem;
ShellContent shellContent = navigationRequest.Request.Content;
bool modalStackPreBuilt = false;
// If we're replacing the whole stack and there are global routes then build the navigation stack before setting the shell section visible
if (navigationRequest.Request.GlobalRoutes.Count > 0 &&
nextActiveSection != null &&
navigationRequest.StackRequest == NavigationRequest.WhatToDoWithTheStack.ReplaceIt)
{
modalStackPreBuilt = true;
bool?isAnimated = (nextActiveSection != currentShellSection) ? false : animate;
await nextActiveSection.GoToAsync(navigationRequest, queryData, isAnimated, isRelativePopping);
}
if (shellItem != null)
{
ApplyQueryAttributes(shellItem, queryData, navigationRequest.Request.Section == null, false);
bool navigatedToNewShellElement = false;
if (shellSection != null && shellContent != null)
{
ApplyQueryAttributes(shellContent, queryData, navigationRequest.Request.GlobalRoutes.Count == 0, isRelativePopping);
if (shellSection.CurrentItem != shellContent)
{
shellSection.SetValueFromRenderer(ShellSection.CurrentItemProperty, shellContent);
navigatedToNewShellElement = true;
}
}
if (shellSection != null)
{
ApplyQueryAttributes(shellSection, queryData, navigationRequest.Request.Content == null, false);
if (shellItem.CurrentItem != shellSection)
{
shellItem.SetValueFromRenderer(ShellItem.CurrentItemProperty, shellSection);
navigatedToNewShellElement = true;
}
}
if (_shell.CurrentItem != shellItem)
{
_shell.SetValueFromRenderer(Shell.CurrentItemProperty, shellItem);
navigatedToNewShellElement = true;
}
if (!modalStackPreBuilt && currentShellSection?.Navigation.ModalStack.Count > 0)
{
// - navigating to new shell element so just pop everything
// - or route contains no global route requests
if (navigatedToNewShellElement || navigationRequest.Request.GlobalRoutes.Count == 0)
{
// remove all non visible pages first so the transition just smoothly goes from
// currently visible modal to base page
if (navigationRequest.Request.GlobalRoutes.Count == 0)
{
for (int i = currentShellSection.Stack.Count - 1; i >= 1; i--)
{
currentShellSection.Navigation.RemovePage(currentShellSection.Stack[i]);
}
}
await currentShellSection.PopModalStackToPage(null, animate);
}
}
if (navigationRequest.Request.GlobalRoutes.Count > 0 && navigationRequest.StackRequest != NavigationRequest.WhatToDoWithTheStack.ReplaceIt)
{
// TODO get rid of this hack and fix so if there's a stack the current page doesn't display
await Device.InvokeOnMainThreadAsync(() =>
{
return(_shell.CurrentItem.CurrentItem.GoToAsync(navigationRequest, queryData, animate, isRelativePopping));
});
}
else if (navigationRequest.Request.GlobalRoutes.Count == 0 &&
navigationRequest.StackRequest == NavigationRequest.WhatToDoWithTheStack.ReplaceIt &&
currentShellSection?.Navigation?.NavigationStack?.Count > 1)
{
// TODO get rid of this hack and fix so if there's a stack the current page doesn't display
await Device.InvokeOnMainThreadAsync(() =>
{
return(_shell.CurrentItem.CurrentItem.GoToAsync(navigationRequest, queryData, animate, isRelativePopping));
});
}
}
else
{
await _shell.CurrentItem.CurrentItem.GoToAsync(navigationRequest, queryData, animate, isRelativePopping);
}
_accumulateNavigatedEvents = false;
// this can be null in the event that no navigation actually took place!
if (_accumulatedEvent != null)
{
HandleNavigated(_accumulatedEvent);
}
}
public Task GoToAsync(ShellNavigationState state, bool?animate, bool enableRelativeShellRoutes, ShellNavigatingEventArgs deferredArgs = null)
{
return(GoToAsync(new ShellNavigationParameters
{
TargetState = state,
Animated = animate,
EnableRelativeShellRoutes = enableRelativeShellRoutes,
DeferredArgs = deferredArgs
}));
}
void Handle_Navigating(object sender, Xamarin.Forms.ShellNavigatingEventArgs e)
{
Console.WriteLine($"SOURCE: {e?.Source.ToString()} | CURRENT: {e.Current?.Location.ToString()} | TARGET: {e.Target?.Location.ToString()}");
}