Cache cell measurements

xamarin · Dec 18, 2020 · 569458d · 569458d
1 parent 322e710
commit 569458d
Show file tree

Hide file tree

Showing 13 changed files with 327 additions and 63 deletions.
diff --git a/.Xamarin.Forms.iOS.slnf b/.Xamarin.Forms.iOS.slnf
@@ -3,8 +3,6 @@
     "path": "Xamarin.Forms.sln",
     "projects": [
       "Stubs\\Xamarin.Forms.Platform.iOS\\Xamarin.Forms.Platform.iOS (Forwarders).csproj",
-      "XFCorePostProcessor.Tasks\\XFCorePostProcessor.Tasks.csproj",
-      "Xamarin.Flex\\Xamarin.Flex.shproj",
       "Xamarin.Forms.Build.Tasks\\Xamarin.Forms.Build.Tasks.csproj",
       "Xamarin.Forms.ControlGallery.iOS\\Xamarin.Forms.ControlGallery.iOS.csproj",
       "Xamarin.Forms.Controls.Issues\\Xamarin.Forms.Controls.Issues.Shared\\Xamarin.Forms.Controls.Issues.Shared.shproj",
@@ -18,8 +16,6 @@
       "Xamarin.Forms.Maps.iOS\\Xamarin.Forms.Maps.iOS.csproj",
       "Xamarin.Forms.Maps\\Xamarin.Forms.Maps.csproj",
       "Xamarin.Forms.Material.iOS\\Xamarin.Forms.Material.iOS.csproj",
-      "Xamarin.Forms.Pages.Azure\\Xamarin.Forms.Pages.Azure.csproj",
-      "Xamarin.Forms.Pages\\Xamarin.Forms.Pages.csproj",
       "Xamarin.Forms.Platform.iOS.UnitTests\\Xamarin.Forms.Platform.iOS.UnitTests.csproj",
       "Xamarin.Forms.Platform.iOS\\Xamarin.Forms.Platform.iOS.csproj",
       "Xamarin.Forms.Platform\\Xamarin.Forms.Platform.csproj",

diff --git a/...in.Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ChatExample.xaml b/...in.Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ChatExample.xaml
@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:chat="clr-namespace:Xamarin.Forms.Controls.GalleryPages.CollectionViewGalleries.ItemSizeGalleries"
+             x:Class="Xamarin.Forms.Controls.GalleryPages.CollectionViewGalleries.ItemSizeGalleries.ChatExample">
+
+    <ContentPage.Resources>
+        <ResourceDictionary>
+            <DataTemplate x:Key="Local">
+                <Grid>
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="*"></ColumnDefinition>
+                        <ColumnDefinition Width="2*"></ColumnDefinition>
+                    </Grid.ColumnDefinitions>
+                    <Frame BorderColor="Green" BackgroundColor="LightGreen" CornerRadius="5" Grid.Column="1">
+                        <StackLayout Margin="2">
+                            <Label Text="{Binding Text}" LineBreakMode="WordWrap" FontSize="10" HorizontalTextAlignment="End" />
+                        </StackLayout>
+                    </Frame>
+                </Grid>
+            </DataTemplate>
+
+            <DataTemplate x:Key="Remote">
+                <Grid Padding="5,0,5,0">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="2*"></ColumnDefinition>
+                        <ColumnDefinition Width="*"></ColumnDefinition>
+                    </Grid.ColumnDefinitions>
+                    <Frame BorderColor="Blue" BackgroundColor="LightBlue" CornerRadius="5">
+                        <StackLayout Margin="2">
+                            <Label Text="{Binding Text}" LineBreakMode="WordWrap" FontSize="10" HorizontalTextAlignment="Start" />
+                        </StackLayout>
+                    </Frame>
+                </Grid>
+            </DataTemplate>
+
+            <chat:ChatTemplateSelector x:Key="ChatTemplateSelector"
+                                                            LocalTemplate="{StaticResource Local}"
+                                                            RemoteTemplate="{StaticResource Remote}"/>
+
+        </ResourceDictionary>
+    </ContentPage.Resources>
+
+    <ContentPage.Content>
+        <Grid>
+            <Grid.RowDefinitions>
+                <RowDefinition Height="Auto"/>
+                <RowDefinition Height="*"/>
+            </Grid.RowDefinitions>
+
+            <StackLayout Orientation="Horizontal">
+                <Button x:Name="AppendRandomSizedItem" Text="Append Random Message" Margin="2" />
+                <Button x:Name="Clear" Text="Clear" Margin="2" />
+                <Button x:Name="Lots" Text="Add 1000 Messages" Margin="2" />
+            </StackLayout>
+
+            <CollectionView ItemsSource="{Binding ChatMessages}" 
+                            ItemTemplate="{StaticResource ChatTemplateSelector}"
+                            ItemSizingStrategy="MeasureAllItems"
+                            Grid.Row="1">
+                <CollectionView.ItemsLayout>
+                    <LinearItemsLayout Orientation="Vertical" ItemSpacing="5"/>
+                </CollectionView.ItemsLayout>
+            </CollectionView>
+
+        </Grid>
+    </ContentPage.Content>
+</ContentPage>
diff --git a/...Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ChatExample.xaml.cs b/...Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ChatExample.xaml.cs
@@ -0,0 +1,115 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using Xamarin.Forms.Xaml;
+
+namespace Xamarin.Forms.Controls.GalleryPages.CollectionViewGalleries.ItemSizeGalleries
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	public partial class ChatExample : ContentPage
+	{
+		Random _random = new Random(DateTime.Now.Millisecond);
+		ChatExampleViewModel _vm = new ChatExampleViewModel();
+
+		public ChatExample()
+		{
+			InitializeComponent();
+			BindingContext = _vm;
+
+			AppendRandomSizedItem.Clicked += AppendRandomChatMessage;
+			Clear.Clicked += ClearMessages;
+			Lots.Clicked += LotsOfMessages;
+		}
+
+		void AppendRandomChatMessage(object sender, EventArgs e)
+		{
+			_vm.ChatMessages.Add(GenerateRandomMessage());
+		}
+
+		void LotsOfMessages(object sender, EventArgs e)
+		{
+			var newVm = new ChatExampleViewModel(GenerateMessages(1000));
+			_vm = newVm;
+			BindingContext = _vm;
+		}
+
+		void ClearMessages(object sender, EventArgs e)
+		{
+			_vm.ChatMessages.Clear();
+		}
+
+		ChatMessage GenerateRandomMessage() 
+		{
+			const string lorem = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut " 
+				+ "labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip " 
+				+ "ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat "
+				+ "nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
+
+			var local = _random.Next(0, 2) == 1;
+
+			var textLength = _random.Next(0, lorem.Length - 1);
+
+			var text = lorem.Substring(0, textLength);
+
+			return new ChatMessage(text, local);
+		}
+
+		IEnumerable<ChatMessage> GenerateMessages(int count)
+		{
+			for (int n = 0; n < count; n++)
+			{
+				yield return GenerateRandomMessage();
+			}
+		}
+	}
+
+	public class ChatExampleViewModel
+	{
+		public ObservableCollection<ChatMessage> ChatMessages { get; }
+
+		public ChatExampleViewModel() 
+		{
+			ChatMessages = new ObservableCollection<ChatMessage>();
+		}
+
+		public ChatExampleViewModel(IEnumerable<ChatMessage> chatMessages) 
+		{ 
+			ChatMessages = new ObservableCollection<ChatMessage>(chatMessages);
+		}
+	}
+
+	public class ChatMessage
+	{
+		public bool IsLocal { get; set; }
+		public string Text { get; set; }
+
+		public ChatMessage(string text) : this(text, true) { }
+
+		public ChatMessage(string text, bool isLocal)
+		{
+			IsLocal = isLocal;
+			Text = text;
+		}
+	}
+
+	class ChatTemplateSelector : DataTemplateSelector
+	{
+		public DataTemplate LocalTemplate { get; set; }
+		public DataTemplate RemoteTemplate { get; set; }
+
+		protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
+		{
+			if (item is ChatMessage message)
+			{
+				if (message.IsLocal)
+				{
+					return LocalTemplate;
+				}
+
+				return RemoteTemplate;
+			}
+
+			throw new ArgumentOutOfRangeException();
+		}
+	}
+}
diff --git a/...Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ItemsSizeGallery.cs b/...Forms.Controls/GalleryPages/CollectionViewGalleries/ItemSizeGalleries/ItemsSizeGallery.cs
@@ -21,7 +21,9 @@ public ItemsSizeGallery()
 						GalleryBuilder.NavButton("Expanding Text (Horizontal List)", () =>
 							new DynamicItemSizeGallery(LinearItemsLayout.Horizontal), Navigation),
 						GalleryBuilder.NavButton("ItemSizing Strategy", () =>
-							new VariableSizeTemplateGridGallery (ItemsLayoutOrientation.Horizontal), Navigation)
+							new VariableSizeTemplateGridGallery (ItemsLayoutOrientation.Horizontal), Navigation),
+						GalleryBuilder.NavButton("Chat Example (Randomly Sized Items)", () =>
+							new ChatExample(), Navigation)
 					}
 				}
 			};

diff --git a/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj b/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj
@@ -70,6 +70,9 @@
     <EmbeddedResource Update="GalleryPages\CollectionViewGalleries\DataTemplateSelectorGalleries\VariedSizeDataTemplateSelectorGallery.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\CollectionViewGalleries\ItemSizeGalleries\ChatExample.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
     <EmbeddedResource Update="GalleryPages\DragAndDropGalleries\DragAndDropBetweenLayouts.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
@@ -88,6 +91,9 @@
     <EmbeddedResource Update="GalleryPages\RadioButtonGalleries\RadioButtonGroupGalleryPage.xaml">
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
     </EmbeddedResource>
+    <Compile Update="GalleryPages\CollectionViewGalleries\ItemSizeGalleries\ChatExample.xaml.cs">
+      <DependentUpon>ChatExample.xaml</DependentUpon>
+    </Compile>
     <Compile Update="GalleryPages\RadioButtonGalleries\RadioButtonGroupGallery.xaml.cs">
       <DependentUpon>RadioButtonGroupGallery.xaml</DependentUpon>
     </Compile>

diff --git a/Xamarin.Forms.Platform.iOS.UnitTests/ObservableItemsSourceTests.cs b/Xamarin.Forms.Platform.iOS.UnitTests/ObservableItemsSourceTests.cs
@@ -1,4 +1,7 @@
-using NUnit.Framework;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using Foundation;
+using NUnit.Framework;
 
 namespace Xamarin.Forms.Platform.iOS.UnitTests
 {
@@ -58,5 +61,26 @@ public void GenerateIndexPathRangeForLoop()
 			Assert.That((int)result[7].Item, Is.EqualTo(13));
 			Assert.That((int)result[8].Item, Is.EqualTo(14));
 		}
+
+		[Test]
+		public void IndexPathValidTest() 
+		{
+			var list = new List<string>
+			{
+				"one",
+				"two",
+				"three"
+			};
+
+			var source = new ListSource(list);
+
+			var valid = NSIndexPath.FromItemSection(2, 0);
+			var invalidItem = NSIndexPath.FromItemSection(7, 0);
+			var invalidSection = NSIndexPath.FromItemSection(1, 9);
+
+			Assert.IsTrue(source.IsIndexPathValid(valid));
+			Assert.IsFalse(source.IsIndexPathValid(invalidItem));
+			Assert.IsFalse(source.IsIndexPathValid(invalidSection));
+		}
 	}
 }
diff --git a/Xamarin.Forms.Platform.iOS/CollectionView/IndexPathHelpers.cs b/Xamarin.Forms.Platform.iOS/CollectionView/IndexPathHelpers.cs
@@ -32,5 +32,20 @@ public static NSIndexPath[] GenerateLoopedIndexPathRange(int section, int sectio
 
 			return result;
 		}
+
+		public static bool IsIndexPathValid(this IItemsViewSource source, NSIndexPath indexPath) 
+		{
+			if (indexPath.Section >= source.GroupCount)
+			{
+				return false;
+			}
+
+			if (indexPath.Item >= source.ItemCountInGroup(indexPath.Section))
+			{
+				return false;
+			}
+
+			return true;
+		}
 	}
 }