From 9cbd3017f9969ed7ab17d3629009b78e5a8028f2 Mon Sep 17 00:00:00 2001
From: Andrei Nitescu <nitescua@yahoo.com>
Date: Mon, 29 Jul 2019 20:37:52 +0300
Subject: [PATCH] CollectionView Android - Fix adapter update (#6840)

* CollectionView Android - Fix adapter update #6840

* Fix missing end tag

* Added APP compiler directive

* Update Issue6644.xaml.cs

fixes #6644
fixes #6839
---
 .../Issue6644.xaml                                 | 13 ++++++++++
 .../Issue6644.xaml.cs                              | 30 ++++++++++++++++++++++
 .../Xamarin.Forms.Controls.Issues.Shared.projitems |  8 ++++++
 .../CollectionView/ItemsViewRenderer.cs            | 17 ++++++++----
 .../CollectionView/SelectableItemsViewRenderer.cs  |  5 ++--
 5 files changed, 65 insertions(+), 8 deletions(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml
new file mode 100644
index 0000000..6dd5437
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml
@@ -0,0 +1,13 @@
+<?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:d="http://xamarin.com/schemas/2014/forms/design"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d"
+             x:Class="Xamarin.Forms.Controls.Issues.Issue6644">
+    <StackLayout>
+        <Button Text="Remove"
+                Clicked="Button1_Clicked" />
+        <CollectionView x:Name="cv" />
+    </StackLayout>
+</ContentPage>
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml.cs
new file mode 100644
index 0000000..c643db0
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue6644.xaml.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 6644, "Android - CollectionView won't animate item remove if EmptyViewTemplate is provided ", PlatformAffected.Android)]
+	public partial class Issue6644 : ContentPage
+	{
+#if APP
+		public Issue6644()
+		{
+			Device.SetFlags(new List<string> { CollectionView.CollectionViewExperimental });
+			InitializeComponent();
+			cv.ItemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10).ToList());
+		}
+
+		void Button1_Clicked(object sender, EventArgs e)
+		{
+			var src = ((ObservableCollection<int>)cv.ItemsSource);
+			if (src.Any())
+				src.RemoveAt(0);
+		}
+#endif
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index caa20ad..90b89c1 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -15,6 +15,9 @@
       <SubType>Code</SubType>
     </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue6609.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue6644.xaml.cs">
+      <SubType>Code</SubType>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)ShellInsets.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CollectionViewGrouping.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue5412.cs" />
@@ -1295,6 +1298,9 @@
     <Compile Update="$(MSBuildThisFileDirectory)Issue6130.xaml.cs">
       <DependentUpon>Issue6130.xaml</DependentUpon>
     </Compile>
+    <Compile Update="$(MSBuildThisFileDirectory)Issue6644.xaml.cs">
+      <DependentUpon>Issue6644.xaml</DependentUpon>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue5268.xaml">
@@ -1309,6 +1315,8 @@
     </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue6644.xaml">
+    </EmbeddedResource>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Github5623.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
diff --git a/Xamarin.Forms.Platform.Android/CollectionView/ItemsViewRenderer.cs b/Xamarin.Forms.Platform.Android/CollectionView/ItemsViewRenderer.cs
index caf7f35..e340338 100644
--- a/Xamarin.Forms.Platform.Android/CollectionView/ItemsViewRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/CollectionView/ItemsViewRenderer.cs
@@ -252,13 +252,19 @@ namespace Xamarin.Forms.Platform.Android
 			UpdateEmptyView();
 		}
 
-		protected virtual void UpdateAdapter()
+		protected virtual ItemsViewAdapter CreateAdapter()
+		{
+			return new ItemsViewAdapter(ItemsView);
+		}
+
+		void UpdateAdapter()
 		{
 			var oldItemViewAdapter = ItemsViewAdapter;
 
-			ItemsViewAdapter = new ItemsViewAdapter(ItemsView);
+			ItemsViewAdapter = CreateAdapter();
 
-			SwapAdapter(ItemsViewAdapter, true);
+			if(GetAdapter() != _emptyViewAdapter)
+				SwapAdapter(ItemsViewAdapter, true);
 
 			oldItemViewAdapter?.Dispose();
 		}
@@ -569,14 +575,15 @@ namespace Xamarin.Forms.Platform.Android
 
 			var showEmptyView = ItemsView?.EmptyView != null && ItemsViewAdapter.ItemCount == 0;
 
-			if (showEmptyView)
+			Adapter currAdapter = GetAdapter();
+			if (showEmptyView && currAdapter != _emptyViewAdapter)
 			{
 				SwapAdapter(_emptyViewAdapter, true);
 
 				// TODO hartez 2018/10/24 17:34:36 If this works, cache this layout manager as _emptyLayoutManager	
 				SetLayoutManager(new LinearLayoutManager(Context));
 			}
-			else
+			else if(!showEmptyView && currAdapter != ItemsViewAdapter)
 			{
 				SwapAdapter(ItemsViewAdapter, true);
 				SetLayoutManager(SelectLayoutManager(_layout));
diff --git a/Xamarin.Forms.Platform.Android/CollectionView/SelectableItemsViewRenderer.cs b/Xamarin.Forms.Platform.Android/CollectionView/SelectableItemsViewRenderer.cs
index b6b56cc..ae05144 100644
--- a/Xamarin.Forms.Platform.Android/CollectionView/SelectableItemsViewRenderer.cs
+++ b/Xamarin.Forms.Platform.Android/CollectionView/SelectableItemsViewRenderer.cs
@@ -37,10 +37,9 @@ namespace Xamarin.Forms.Platform.Android
 			UpdateNativeSelection();
 		}
 
-		protected override void UpdateAdapter()
+		protected override ItemsViewAdapter CreateAdapter()
 		{
-			ItemsViewAdapter = new SelectableItemsViewAdapter(SelectableItemsView);
-			SwapAdapter(ItemsViewAdapter, true);
+			return new SelectableItemsViewAdapter(SelectableItemsView);
 		}
 
 		void UpdateNativeSelection()
-- 
2.7.4