Merge pull request #13 from Redth/memory-analyzer-fixes

Memory analyzer fixes

Author: Redth

Sample/VirtualListViewSample/Platforms/Android/AndroidManifest.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
-	<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" />
+	<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="34" />
 	<application>
 	</application>
 	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

Sample/VirtualListViewSample/VirtualListViewSample.csproj

@@ -27,6 +27,8 @@
 	<ItemGroup>
 		<PackageReference Include="CommunityToolkit.Mvvm" Version="8.2.2" />
 		<PackageReference Include="LiteDb" Version="5.0.17" />
+		<PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiVersion)" />
+		<PackageReference Include="Microsoft.Maui.Controls.Compatibility" Version="$(MauiVersion)" />
 	</ItemGroup>
 	<ItemGroup>
 		<EmbeddedResource Include="chinook.litedb" />

VirtualListView/Apple/CvCell.ios.maccatalyst.cs

@@ -1,6 +1,7 @@
 using CoreGraphics;
 using Foundation;
 using Microsoft.Maui.Platform;
+using System.Diagnostics.CodeAnalysis;
 using UIKit;
 
 namespace Microsoft.Maui;
@@ -9,27 +10,41 @@ internal class CvCell : UICollectionViewCell
 {
 	public VirtualListViewHandler Handler { get; set; }
 
-	public NSIndexPath IndexPath { get; set; }
+	public WeakReference<NSIndexPath> IndexPath { get; set; }
 
 	public PositionInfo PositionInfo { get; set; }
 
-	public Action<IView> ReuseCallback { get; set; }
+	public WeakReference<Action<IView>> ReuseCallback { get; set; }
 
 	[Export("initWithFrame:")]
 	public CvCell(CGRect frame) : base(frame)
 	{
 		this.ContentView.AddGestureRecognizer(new UITapGestureRecognizer(() => InvokeTap()));
 	}
 
-	public Action<CvCell> TapHandler { get; set; }
+	public WeakReference<Action<CvCell>> TapHandler { get; set; }
 
-	UIKeyCommand[] keyCommands;
+	WeakReference<UIKeyCommand[]> keyCommands;
 
-	public override UIKeyCommand[] KeyCommands => keyCommands ??= new[]
+	public override UIKeyCommand[] KeyCommands
 	{
-		UIKeyCommand.Create(new NSString("\r"), 0, new ObjCRuntime.Selector("keyCommandSelect")),
-		UIKeyCommand.Create(new NSString(" "), 0, new ObjCRuntime.Selector("keyCommandSelect")),
-	};
+		get
+		{
+			if (keyCommands?.TryGetTarget(out var commands) ?? false)
+                return commands;
+
+			var v = new[]
+			{
+				UIKeyCommand.Create(new NSString("\r"), 0, new ObjCRuntime.Selector("keyCommandSelect")),
+				UIKeyCommand.Create(new NSString(" "), 0, new ObjCRuntime.Selector("keyCommandSelect")),
+			};
+
+            keyCommands = new WeakReference<UIKeyCommand[]>(v);
+
+			return v;
+		}
+
+	}
 
 	[Export("keyCommandSelect")]
 	public void KeyCommandSelect()
@@ -40,54 +55,85 @@ public void KeyCommandSelect()
 	void InvokeTap()
 	{
 		if (PositionInfo.Kind == PositionKind.Item)
-			TapHandler?.Invoke(this);
+		{
+			if (TapHandler?.TryGetTarget(out var handler) ?? false)
+				handler?.Invoke(this);
+		}
+	}
+
+	public void UpdateSelected(bool selected)
+	{
+		PositionInfo.IsSelected = selected;
+
+		if (VirtualView?.TryGetTarget(out var virtualView) ?? false)
+		{
+			if (virtualView is IPositionInfo positionInfo)
+			{
+				positionInfo.IsSelected = selected;
+				virtualView.Handler?.UpdateValue(nameof(PositionInfo.IsSelected));
+			}
+		}
 	}
 
 	public override UICollectionViewLayoutAttributes PreferredLayoutAttributesFittingAttributes(UICollectionViewLayoutAttributes layoutAttributes)
 	{
-		if (NativeView == null || VirtualView == null)
-			return layoutAttributes;
+		if ((NativeView is not null && NativeView.TryGetTarget(out var _))
+			&& (VirtualView is not null && VirtualView.TryGetTarget(out var virtualView)))
+		{
+			var measure = virtualView.Measure(layoutAttributes.Size.Width, double.PositiveInfinity);
 
-		var measure = VirtualView.Measure(layoutAttributes.Size.Width, double.PositiveInfinity);
+			layoutAttributes.Frame = new CGRect(0, layoutAttributes.Frame.Y, layoutAttributes.Frame.Width, measure.Height);
 
-		layoutAttributes.Frame = new CGRect(0, layoutAttributes.Frame.Y, layoutAttributes.Frame.Width, measure.Height);
+			return layoutAttributes;
+		}
 
 		return layoutAttributes;
 	}
 
 	public bool NeedsView
-		=> NativeView == null;
+		=> NativeView == null || !NativeView.TryGetTarget(out var _);
 
-	public IView VirtualView { get; private set; }
+	public WeakReference<IView> VirtualView { get; set; }
 
-	public UIView NativeView { get; private set; }
+	public WeakReference<UIView> NativeView { get; set; }
 
 	public override void PrepareForReuse()
 	{
 		base.PrepareForReuse();
 
 		// TODO: Recycle
-		if (VirtualView != null)
-			ReuseCallback?.Invoke(VirtualView);
+		if ((VirtualView?.TryGetTarget(out var virtualView) ?? false)
+			&& (ReuseCallback?.TryGetTarget(out var reuseCallback) ?? false))
+		{
+			reuseCallback?.Invoke(virtualView);
+		}
 	}
 
 	public void SwapView(IView newView)
 	{
-		if (VirtualView == null || VirtualView.Handler == null || NativeView == null)
+        // Create a new platform native view if we don't have one yet
+        if (!(NativeView?.TryGetTarget(out var nativeView) ?? false))
+        {
+            nativeView = newView.ToPlatform(this.Handler.MauiContext);
+            nativeView.Frame = this.ContentView.Frame;
+            nativeView.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth;
+            this.ContentView.AddSubview(nativeView);
+            NativeView = new WeakReference<UIView>(nativeView);
+        }
+
+		// Create a new virtual view if we don't have one yet
+		if (!(VirtualView?.TryGetTarget(out var virtualView) ?? false) || (virtualView?.Handler is null))
 		{
-			NativeView = newView.ToPlatform(this.Handler.MauiContext);
-			VirtualView = newView;
-			NativeView.Frame = this.ContentView.Frame;
-			NativeView.AutoresizingMask = UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleWidth;
-			this.ContentView.AddSubview(NativeView);
+			virtualView = newView;
+			VirtualView = new WeakReference<IView>(virtualView);
 		}
 		else
 		{
-			var handler = VirtualView.Handler;
-			VirtualView.Handler = null;
+			var handler = virtualView.Handler;
+			virtualView.Handler = null;
 			newView.Handler = handler;
 			handler.SetVirtualView(newView);
-			VirtualView = newView;
+			VirtualView.SetTarget(newView);
 		}
-	}
+    }
 }

VirtualListView/Apple/CvDataSource.ios.maccatalyst.cs

@@ -40,12 +40,15 @@ public override UICollectionViewCell GetCell(UICollectionView collectionView, NS
 		};
 
 		var cell = collectionView.DequeueReusableCell(nativeReuseId, indexPath) as CvCell;
-		cell.TapHandler = TapCellHandler;
+		cell.TapHandler = new WeakReference<Action<CvCell>>(TapCellHandler);
 		cell.Handler = Handler;
-		cell.IndexPath = indexPath;
-		
-		cell.ReuseCallback = rv =>
-			Handler.VirtualView.ViewSelector.ViewDetached(info, cell.VirtualView);
+		cell.IndexPath = new WeakReference<NSIndexPath>(indexPath);
+
+		cell.ReuseCallback = new WeakReference<Action<IView>>((rv) =>
+		{
+			if (cell?.VirtualView?.TryGetTarget(out var cellVirtualView) ?? false)
+				Handler.VirtualView.ViewSelector.ViewDetached(info, cellVirtualView);
+		});
 
 		if (info.SectionIndex < 0 || info.ItemIndex < 0)
 			info.IsSelected = false;
@@ -60,12 +63,15 @@ public override UICollectionViewCell GetCell(UICollectionView collectionView, NS
 
 		cell.PositionInfo = info;
 
-		if (cell.VirtualView is IPositionInfo viewPositionInfo)
-			viewPositionInfo.IsSelected = info.IsSelected;
+		if (cell.VirtualView.TryGetTarget(out var cellVirtualView))
+		{
+			if (cellVirtualView is IPositionInfo viewPositionInfo)
+				viewPositionInfo.IsSelected = info.IsSelected;
 
-		Handler?.PositionalViewSelector?.ViewSelector?.RecycleView(info, data, cell.VirtualView);
+			Handler?.PositionalViewSelector?.ViewSelector?.RecycleView(info, data, cellVirtualView);
 
-		Handler.VirtualView.ViewSelector.ViewAttached(info, cell.VirtualView);
+			Handler.VirtualView.ViewSelector.ViewAttached(info, cellVirtualView);
+		}
 
 		return cell;
 	}

VirtualListView/Apple/CvDelegate.ios.maccatalyst.cs

@@ -10,13 +10,13 @@ public CvDelegate(VirtualListViewHandler handler, UICollectionView collectionVie
 		: base()
 	{
 		Handler = handler;
-		NativeCollectionView = collectionView;
+		NativeCollectionView = new WeakReference<UICollectionView>(collectionView);
 	}
 
-	internal readonly UICollectionView NativeCollectionView;
+	internal readonly WeakReference<UICollectionView> NativeCollectionView;
 	internal readonly VirtualListViewHandler Handler;
 
-	public Action<NFloat, NFloat> ScrollHandler { get; set; }
+	public WeakReference<Action<NFloat, NFloat>> ScrollHandler { get; set; }
 
 	public override void ItemSelected(UICollectionView collectionView, NSIndexPath indexPath)
 		=> HandleSelection(collectionView, indexPath, true);
@@ -31,7 +31,7 @@ void HandleSelection(UICollectionView collectionView, NSIndexPath indexPath, boo
 
 		if ((selectedCell?.PositionInfo?.Kind ?? PositionKind.Header) == PositionKind.Item)
 		{
-			selectedCell.PositionInfo.IsSelected = selected;
+			selectedCell.UpdateSelected(selected);
 
 			var itemPos = new ItemPosition(
 				selectedCell.PositionInfo.SectionIndex,
@@ -45,7 +45,10 @@ void HandleSelection(UICollectionView collectionView, NSIndexPath indexPath, boo
 	}
 
 	public override void Scrolled(UIScrollView scrollView)
-		=> ScrollHandler?.Invoke(scrollView.ContentOffset.X, scrollView.ContentOffset.Y);
+	{
+		if (ScrollHandler?.TryGetTarget(out var handler) ?? false)
+			handler?.Invoke(scrollView.ContentOffset.X, scrollView.ContentOffset.Y);
+	}
 
 	public override bool ShouldSelectItem(UICollectionView collectionView, NSIndexPath indexPath)
 		=> IsRealItem(indexPath);