Fix UI pattern for AspectRatioLayoutElement.

Assets/Cryville/Common/Unity/UI/AspectRatioLayoutElement.cs

@@ -6,6 +6,7 @@ namespace Cryville.Common.Unity.UI {
 	/// <summary>
 	/// A <see cref="ILayoutElement" /> that takes the length of one axis to compute the preferred length of the other axis with respect to a aspect ratio.
 	/// </summary>
+	[ExecuteAlways]
 	public class AspectRatioLayoutElement : UIBehaviour, ILayoutElement {
 		[SerializeField]
 		[Tooltip("The aspect ratio. Width divided by height.")]
@@ -35,32 +36,27 @@ namespace Cryville.Common.Unity.UI {
 			SetDirty();
 		}
 
-		private void SetDirty() {
-			if (!IsActive()) return;
-			LayoutRebuilder.MarkLayoutForRebuild(transform as RectTransform);
-		}
-
 		/// <inheritdoc />
 		public float minWidth {
 			get {
-				return m_isVertical ? 0 : (transform as RectTransform).rect.height * m_aspectRatio;
+				return m_isVertical ? -1 : (transform as RectTransform).rect.height * m_aspectRatio;
 			}
 		}
 		/// <inheritdoc />
 		public float preferredWidth { get { return minWidth; } }
 		/// <inheritdoc />
-		public float flexibleWidth { get { return 0; } }
+		public float flexibleWidth { get { return -1; } }
 
 		/// <inheritdoc />
 		public float minHeight {
 			get {
-				return m_isVertical ? (transform as RectTransform).rect.width / m_aspectRatio : 0;
+				return m_isVertical ? (transform as RectTransform).rect.width / m_aspectRatio : -1;
 			}
 		}
 		/// <inheritdoc />
 		public float preferredHeight { get { return minHeight; } }
 		/// <inheritdoc />
-		public float flexibleHeight { get { return 0; } }
+		public float flexibleHeight { get { return -1; } }
 
 		/// <inheritdoc />
 		public int layoutPriority { get { return 1; } }
@@ -71,34 +67,44 @@ namespace Cryville.Common.Unity.UI {
 		/// <inheritdoc />
 		public void CalculateLayoutInputVertical() { }
 
-		protected override void OnDidApplyAnimationProperties() {
-			base.OnDidApplyAnimationProperties();
-			SetDirty();
-		}
-
-		protected override void OnDisable() {
-			SetDirty();
-			base.OnDisable();
-		}
-
 		protected override void OnEnable() {
 			base.OnEnable();
 			SetDirty();
 		}
-
-		protected override void OnRectTransformDimensionsChange() {
-			base.OnRectTransformDimensionsChange();
+		protected override void OnBeforeTransformParentChanged() {
+			base.OnBeforeTransformParentChanged();
 			SetDirty();
 		}
-
 		protected override void OnTransformParentChanged() {
 			base.OnTransformParentChanged();
 			SetDirty();
 		}
-
-		// Overriding fails compiler
-		new void OnValidate() {
+		protected override void OnDidApplyAnimationProperties() {
+			base.OnDidApplyAnimationProperties();
 			SetDirty();
 		}
+		protected override void OnValidate() {
+			base.OnValidate();
+			SetDirty();
+		}
+		protected override void OnDisable() {
+			SetDirty();
+			base.OnDisable();
+		}
+		protected override void OnRectTransformDimensionsChange() {
+			base.OnRectTransformDimensionsChange();
+			SetDirty();
+		}
+		bool _delayedSetDirty;
+		private void SetDirty() {
+			if (!IsActive()) return;
+			if (CanvasUpdateRegistry.IsRebuildingLayout()) _delayedSetDirty = true;
+			else LayoutRebuilder.MarkLayoutForRebuild(transform as RectTransform);
+		}
+		void Update() {
+			if (!_delayedSetDirty) return;
+			_delayedSetDirty = false;
+			LayoutRebuilder.MarkLayoutForRebuild(transform as RectTransform);
+		}
 	}
 }