maui-linux/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6077.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Xamarin.Forms.CustomAttributes;
using Xamarin.Forms.Internals;
using Xamarin.Forms.PlatformConfiguration;
using Xamarin.Forms.PlatformConfiguration.iOSSpecific;

#if UITEST
using Xamarin.Forms.Core.UITests;
using Xamarin.UITest;
using NUnit.Framework;
#endif

namespace Xamarin.Forms.Controls.Issues
{
#if UITEST
	[NUnit.Framework.Category(UITestCategories.CollectionView)]
#endif
	[Preserve(AllMembers = true)]
	[Issue(IssueTracker.Github, 6077, "CollectionView (iOS) using horizontal grid does not display last column of uneven item count", PlatformAffected.iOS)]
	public class Issue6077 : TestNavigationPage
	{
		[Preserve(AllMembers = true)]
		public class MainViewModel : INotifyPropertyChanged
		{
			readonly IList<ItemModel> _items;
			public ObservableCollection<ItemModel> Items { get; private set; }

			public MainViewModel()
			{
				_items = new List<ItemModel>();
				CreateItemsCollection();
			}

			void CreateItemsCollection(int items = 5)
			{
				for (int n = 0; n < items; n++)
				{
					_items.Add(new ItemModel
					{
						Title = $"Item {n + 1}",
					});
				}

				Items = new ObservableCollection<ItemModel>(_items);
			}

			protected bool SetProperty<T>(ref T backingStore, T value,
				[CallerMemberName]string propertyName = "",
				Action onChanged = null)
			{
				if (EqualityComparer<T>.Default.Equals(backingStore, value))
					return false;

				backingStore = value;
				onChanged?.Invoke();
				OnPropertyChanged(propertyName);
				return true;
			}

			#region INotifyPropertyChanged
			public event PropertyChangedEventHandler PropertyChanged;
			protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
			{
				var changed = PropertyChanged;
				if (changed == null)
					return;

				changed.Invoke(this, new PropertyChangedEventArgs(propertyName));
			}
			#endregion
		}

		[Preserve(AllMembers = true)]
		public class ItemModel
		{
			public string Title { get; set; }
		}

		ContentPage CreateRoot()
		{
			var page = new ContentPage { Title = "Issue6077" };

			var cv = new CollectionView { ItemSizingStrategy = ItemSizingStrategy.MeasureAllItems };

			var itemsLayout = new GridItemsLayout(3, ItemsLayoutOrientation.Horizontal);
			

			cv.ItemsLayout = itemsLayout;

			var template = new DataTemplate(() => {
				var grid = new Grid { HeightRequest = 100, WidthRequest = 50, BackgroundColor = Color.AliceBlue };

				grid.RowDefinitions = new RowDefinitionCollection { new RowDefinition { Height = new GridLength(100) } };
				grid.ColumnDefinitions = new ColumnDefinitionCollection { new ColumnDefinition { Width = new GridLength(50) } };

				var label = new Label { };

				label.SetBinding(Label.TextProperty, new Binding("Title"));

				var content = new ContentView { Content = label };

				grid.Children.Add(content);

				return grid;
			});

			cv.ItemTemplate = template;
			cv.SetBinding(ItemsView.ItemsSourceProperty, new Binding("Items"));

			page.Content = cv;

			BindingContext = new MainViewModel();

			return page;
		}

		protected override void Init()
		{
#if APP
			Device.SetFlags(new List<string>(Device.Flags ?? new List<string>()) { "CollectionView_Experimental" });

			PushAsync(CreateRoot());
#endif
		}

#if UITEST
		[Test]
		public void LastColumnShouldBeVisible()
		{
			// If the partial column shows up, then Item 5 will be in it
			RunningApp.WaitForElement("Item 5");
		}
#endif
	}
}