feat: Basic implementation for detecting layout cycles

(cherry picked from commit f2b46b3)

src/Uno.UI/Generated/3.0.0.0/Microsoft.UI.Xaml/DebugSettings.cs

@@ -39,20 +39,6 @@ public bool IsXamlResourceReferenceTracingEnabled
 			}
 		}
 #endif
-#if __ANDROID__ || __IOS__ || IS_UNIT_TESTS || __WASM__ || __SKIA__ || __NETSTD_REFERENCE__ || __MACOS__
-		[global::Uno.NotImplemented("__ANDROID__", "__IOS__", "IS_UNIT_TESTS", "__WASM__", "__SKIA__", "__NETSTD_REFERENCE__", "__MACOS__")]
-		public global::Microsoft.UI.Xaml.LayoutCycleTracingLevel LayoutCycleTracingLevel
-		{
-			get
-			{
-				throw new global::System.NotImplementedException("The member LayoutCycleTracingLevel DebugSettings.LayoutCycleTracingLevel is not implemented. For more information, visit https://aka.platform.uno/notimplemented#m=LayoutCycleTracingLevel%20DebugSettings.LayoutCycleTracingLevel");
-			}
-			set
-			{
-				global::Windows.Foundation.Metadata.ApiInformation.TryRaiseNotImplemented("Microsoft.UI.Xaml.DebugSettings", "LayoutCycleTracingLevel DebugSettings.LayoutCycleTracingLevel");
-			}
-		}
-#endif
 #if __ANDROID__ || __IOS__ || IS_UNIT_TESTS || __WASM__ || __SKIA__ || __NETSTD_REFERENCE__ || __MACOS__
 		[global::Uno.NotImplemented("__ANDROID__", "__IOS__", "IS_UNIT_TESTS", "__WASM__", "__SKIA__", "__NETSTD_REFERENCE__", "__MACOS__")]
 		public global::Microsoft.UI.Xaml.LayoutCycleDebugBreakLevel LayoutCycleDebugBreakLevel

src/Uno.UI/UI/Xaml/DebugSettings.cs

@@ -5,6 +5,8 @@ namespace Microsoft.UI.Xaml
 {
 	public sealed partial class DebugSettings
 	{
+		public LayoutCycleTracingLevel LayoutCycleTracingLevel { get; set; }
+
 		[Uno.NotImplemented]
 		public bool EnableFrameRateCounter { get; set; }
 

src/Uno.UI/UI/Xaml/FrameworkElement.Layout.crossruntime.cs

@@ -168,6 +168,11 @@ void MeasureCoreWithTrace(Size availableSize)
 
 		private void InnerMeasureCore(Size availableSize)
 		{
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] Measuring {this},{this.GetDebugName()} with availableSize {availableSize}.");
+			}
+
 			// Uno TODO
 			//CLayoutManager* pLayoutManager = VisualTree::GetLayoutManagerForElement(this);
 			//bool bInLayoutTransition = pLayoutManager ? pLayoutManager->GetTransitioningElement() == this : false;
@@ -351,6 +356,11 @@ private void InnerMeasureCore(Size availableSize)
 				desiredSize.Height = LayoutRound(desiredSize.Height);
 			}
 
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] Measured {this},{this.GetDebugName()}: desiredSize is {desiredSize}.");
+			}
+
 #if __SKIA__
 			if (desiredSize != DesiredSize)
 #endif
@@ -432,6 +442,10 @@ void ArrangeCoreWithTrace(Rect finalRect)
 		private void InnerArrangeCore(Rect finalRect)
 		{
 			_logDebug?.Debug($"{DepthIndentation}{FormatDebugName()}: InnerArrangeCore({finalRect})");
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] Arranging {this},{this.GetDebugName()} with finalRect {finalRect}.");
+			}
 
 			// Uno TODO:
 			//CLayoutManager* pLayoutManager = VisualTree::GetLayoutManagerForElement(this);
@@ -719,6 +733,11 @@ private void InnerArrangeCore(Rect finalRect)
 			var clippedFrame = GetClipRect(needsClipBounds, visualOffset, finalRect, new Size(maxWidth, maxHeight), margin);
 			ArrangeNative(visualOffset, clippedFrame);
 
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] Arranged {this},{this.GetDebugName()}: {clippedFrame}.");
+			}
+
 			AfterArrange();
 		}
 

src/Uno.UI/UI/Xaml/UIElement.Layout.crossruntime.cs

@@ -27,6 +27,11 @@ public void InvalidateMeasure()
 				return;
 			}
 
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] InvalidateMeasure {this},{this.GetDebugName()}");
+			}
+
 			SetLayoutFlags(LayoutFlag.MeasureDirty);
 
 			if (FeatureConfiguration.UIElement.UseInvalidateMeasurePath && !IsMeasureDirtyPathDisabled)
@@ -81,6 +86,11 @@ public void InvalidateArrange()
 				return; // Already dirty
 			}
 
+			if (_traceLayoutCycle && this.Log().IsEnabled(LogLevel.Error))
+			{
+				this.Log().LogError($"[LayoutCycleTracing] InvalidateArrange {this},{this.GetDebugName()}");
+			}
+
 			SetLayoutFlags(LayoutFlag.ArrangeDirty);
 
 			if (FeatureConfiguration.UIElement.UseInvalidateArrangePath && !IsArrangeDirtyPathDisabled)

src/Uno.UI/UI/Xaml/UIElement.cs

@@ -44,6 +44,7 @@ namespace Microsoft.UI.Xaml
 {
 	public partial class UIElement : DependencyObject, IXUidProvider, IUIElement
 	{
+		private protected static bool _traceLayoutCycle;
 		private static readonly TypedEventHandler<UIElement, BringIntoViewRequestedEventArgs> OnBringIntoViewRequestedHandler =
 			(UIElement sender, BringIntoViewRequestedEventArgs args) => sender.OnBringIntoViewRequested(args);
 
@@ -824,6 +825,15 @@ private static void InnerUpdateLayout(UIElement root)
 
 			for (var i = MaxLayoutIterations; i > 0; i--)
 			{
+				if (i <= 10 && Application.Current is { DebugSettings.LayoutCycleTracingLevel: not LayoutCycleTracingLevel.None })
+				{
+					_traceLayoutCycle = true;
+					if (typeof(UIElement).Log().IsEnabled(LogLevel.Error))
+					{
+						typeof(UIElement).Log().LogError($"[LayoutCycleTracing] Low on countdown ({i}).");
+					}
+				}
+
 				if (root.IsMeasureDirtyOrMeasureDirtyPath)
 				{
 					root.Measure(bounds.Size);
@@ -863,17 +873,20 @@ private static void InnerUpdateLayout(UIElement root)
 						!root.IsArrangeDirtyOrArrangeDirtyPath &&
 						!eventManager.HasPendingViewportChangedEvents)
 					{
+						_traceLayoutCycle = false;
 						return;
 					}
 				}
 #else
 				else
 				{
+					_traceLayoutCycle = false;
 					return;
 				}
 #endif
 			}
 
+			_traceLayoutCycle = false;
 			throw new InvalidOperationException("Layout cycle detected.");
 #endif
 		}