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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms.Internals;
namespace Xamarin.Forms.Controls
{
public class ListPage : ContentPage
{
ListScreen _listScreen;
public ListPage ()
{
_listScreen = new ListScreen ();
Content = new StackLayout {
Children = {
new Label {Text = "Foo"},
_listScreen.View
}
};
}
}
public class ListScreen
{
public ListView View { get; private set; }
internal class A : INotifyPropertyChanged
{
string _text;
public string Text {
get {
return _text;
}
set {
_text = value;
if(PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs("Text"));
}
}
#region INotifyPropertyChanged implementation
public event PropertyChangedEventHandler PropertyChanged;
#endregion
}
[Preserve (AllMembers = true)]
internal class ViewCellTest : ViewCell
{
static int s_inc = 0;
public ViewCellTest ()
{
var stackLayout = new StackLayout {
Orientation = StackOrientation.Horizontal
};
var label = new Label ();
label.SetBinding (Label.TextProperty, "Text");
var box = new BoxView {WidthRequest = 100, HeightRequest = 10, Color = Color.Red};
stackLayout.Children.Add (label);
stackLayout.Children.Add (box);
View = stackLayout;
}
protected override void OnAppearing ()
{
base.OnAppearing ();
Debug.WriteLine ("Appearing: " + (BindingContext as A)?.Text + " : " + s_inc);
s_inc++;
}
protected override void OnDisappearing ()
{
base.OnDisappearing ();
Debug.WriteLine ("Disappearing: " + (BindingContext as A)?.Text + " : " + s_inc);
s_inc++;
}
}
public ListScreen ()
{
View = new ListView (ListViewCachingStrategy.RecycleElement);
View.RowHeight = 30;
var n = 500;
var items = Enumerable.Range (0, n).Select (i => new A {Text = i.ToString ()}).ToList ();
View.ItemsSource = items;
View.ItemTemplate = new DataTemplate (typeof (ViewCellTest));
View.ItemSelected += (sender, e) => {
var cell = (e.SelectedItem as A);
if (cell == null)
return;
var x = int.Parse (cell.Text);
if (x == 5) {
n += 10;
View.ItemsSource = Enumerable.Range (0, n).Select (i => new A { Text = i.ToString () }).ToList ();
} else {
cell.Text = (x + 1).ToString ();
}
};
}
}
}
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