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using System;
using Xamarin.Forms;
using System.Diagnostics;
using System.Collections.Generic;
namespace Xamarin.Forms.Controls
{
public class AppearingGalleryPage : ContentPage
{
const string NavPageTitle = "NavAppearingPage";
const string MasterPageTitle = "MasterAppearingPage";
const string TabbedPageTitle = "TabbedAppearingPage";
const string CarouselPageTitle = "CarouselAppearingPage";
public AppearingGalleryPage ()
{
var initalPage = new AppearingPage (1);
var initalPage2 = new AppearingPage (2);
Content = new StackLayout {
Children = {
new Button { Text = NavPageTitle, Command = new Command (() => {
Application.Current.MainPage = new NavAppearingPage(initalPage);
})
},
new Button { Text = MasterPageTitle, Command = new Command (() => {
var page = new MasterDetailPage {
Title = MasterPageTitle,
Master = new ContentPage { Title = "Master", BackgroundColor = Color.Red },
Detail = new NavAppearingPage(initalPage)
};
SetMainPage (page);
})
},
new Button { Text = TabbedPageTitle, Command = new Command (() => {
var page = new TabbedPage {
Title = TabbedPageTitle,
Children = { initalPage, initalPage2 }
};
SetMainPage (page);
})
},
new Button { Text = CarouselPageTitle, Command = new Command (() => {
var page = new CarouselPage {
Title = CarouselPageTitle,
Children = { initalPage, initalPage2 }
};
SetMainPage (page);
})
}
}
};
}
static void SetMainPage (Page page)
{
var tracker = new AppearingTracker (page);
Application.Current.MainPage = page;
}
class AppearingTracker
{
int _isAppearingFired;
int _isDisappearingFired;
public AppearingTracker (Page page)
{
page.Appearing += (object sender, EventArgs e) => {
_isAppearingFired++;
App.AppearingMessages.Insert (0, $"Appearing {page.Title}");
Debug.WriteLine ($"Appearing {page.Title}");
};
page.Disappearing += (object sender, EventArgs e) => {
_isDisappearingFired++;
App.AppearingMessages.Insert (0, $"Disappearing {page.Title}");
Debug.WriteLine( $"Disappearing {page.Title}");
};
}
}
class AppearingPage : ContentPage
{
int _theId;
ListView _listMessages;
public AppearingPage (int id)
{
var tracker = new AppearingTracker (this);
_listMessages = new ListView ();
_theId = id;
Title = $"Page {_theId}";
Padding = new Thickness (20);
Content = new StackLayout {
Children = {
new Label { Text = $"Hello Appearing {_theId} page" },
new Button { Text = "Push new Page", Command = new Command ( async () => { await Navigation.PushAsync( new AppearingPage(2)); }) },
new Button { Text = "Pop page", Command = new Command ( async () => { await Navigation.PopAsync(); }) },
new Button { Text = "Pop to root", Command = new Command ( async () => { await Navigation.PopToRootAsync(); }) },
new Button { Text = "Change Main Page", Command = new Command ( () => {
App.AppearingMessages.Clear();
Application.Current.MainPage = new AppearingPage(3); })
},
_listMessages
}
};
}
protected override void OnAppearing ()
{
base.OnAppearing ();
Device.StartTimer (new TimeSpan (200), () => {
_listMessages.ItemsSource = App.AppearingMessages;
return false;
});
}
}
class NavAppearingPage : NavigationPage
{
public NavAppearingPage (Page page) : base(page)
{
Title = NavPageTitle;
var tracker = new AppearingTracker (this);
}
}
}
}
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