[C, iOS, Android] LayoutCompression (#1136)

* [C, iOS, Android] LayoutCompression

* fix docs

* minor fixups

3 files changed, 30 insertions, 16 deletions

diff --git a/Xamarin.Forms.Platform.iOS/RendererPool.cs b/Xamarin.Forms.Platform.iOS/RendererPool.cs
index 563201f0..e95148da 100644
--- a/Xamarin.Forms.Platform.iOS/RendererPool.cs
+++ b/Xamarin.Forms.Platform.iOS/RendererPool.cs
@@ -108,10 +108,14 @@ namespace Xamarin.Forms.Platform.MacOS
 				var child = logicalChild as VisualElement;
 				if (child != null)
 				{
-					var renderer = GetFreeRenderer(child) ?? Platform.CreateRenderer(child);
-					Platform.SetRenderer(child, renderer);
-
-					_parent.NativeView.AddSubview(renderer.NativeView);
+					if (CompressedLayout.GetIsHeadless(child)) {
+						child.IsPlatformEnabled = true;
+						FillChildrenWithRenderers(child);
+					} else {
+						var renderer = GetFreeRenderer(child) ?? Platform.CreateRenderer(child);
+						Platform.SetRenderer(child, renderer);
+						_parent.NativeView.AddSubview(renderer.NativeView);
+					}
 				}
 			}
 		}
diff --git a/Xamarin.Forms.Platform.iOS/VisualElementPackager.cs b/Xamarin.Forms.Platform.iOS/VisualElementPackager.cs
index fa91cf6a..72ab654a 100644
--- a/Xamarin.Forms.Platform.iOS/VisualElementPackager.cs
+++ b/Xamarin.Forms.Platform.iOS/VisualElementPackager.cs
@@ -13,16 +13,20 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		bool _isDisposed;
 
-		IElementController ElementController => Renderer.Element as IElementController;
+		IElementController ElementController => _element;
 
-		public VisualElementPackager(IVisualElementRenderer renderer)
+		public VisualElementPackager(IVisualElementRenderer renderer) : this(renderer, null)
+		{
+		}
+
+		VisualElementPackager(IVisualElementRenderer renderer, VisualElement element)
 		{
 			if (renderer == null)
 				throw new ArgumentNullException(nameof(renderer));
 
 			Renderer = renderer;
 			renderer.ElementChanged += OnRendererElementChanged;
-			SetElement(null, renderer.Element);
+			SetElement(null, element ?? renderer.Element);
 		}
 
 		protected IVisualElementRenderer Renderer { get; set; }
@@ -65,16 +69,22 @@ namespace Xamarin.Forms.Platform.MacOS
 			if (_isDisposed)
 				return;
 
-			var viewRenderer = Platform.CreateRenderer(view);
-			Platform.SetRenderer(view, viewRenderer);
+			if (CompressedLayout.GetIsHeadless(view)) {
+				var packager = new VisualElementPackager(Renderer, view);
+				view.IsPlatformEnabled = true;
+				packager.Load();
+			} else {
+				var viewRenderer = Platform.CreateRenderer(view);
+				Platform.SetRenderer(view, viewRenderer);
 
-			var uiview = Renderer.NativeView;
-			uiview.AddSubview(viewRenderer.NativeView);
+				var uiview = Renderer.NativeView;
+				uiview.AddSubview(viewRenderer.NativeView);
 
-			if (Renderer.ViewController != null && viewRenderer.ViewController != null)
-				Renderer.ViewController.AddChildViewController(viewRenderer.ViewController);
+				if (Renderer.ViewController != null && viewRenderer.ViewController != null)
+					Renderer.ViewController.AddChildViewController(viewRenderer.ViewController);
 
-			EnsureChildrenOrder();
+				EnsureChildrenOrder();
+			}
 		}
 
 		protected virtual void OnChildRemoved(VisualElement view)
diff --git a/Xamarin.Forms.Platform.iOS/VisualElementTracker.cs b/Xamarin.Forms.Platform.iOS/VisualElementTracker.cs
index 5c84b991..68625a32 100644
--- a/Xamarin.Forms.Platform.iOS/VisualElementTracker.cs
+++ b/Xamarin.Forms.Platform.iOS/VisualElementTracker.cs
@@ -138,8 +138,8 @@ namespace Xamarin.Forms.Platform.MacOS
 			var scale = (float)view.Scale;
 			var width = (float)view.Width;
 			var height = (float)view.Height;
-			var x = (float)view.X;
-			var y = (float)view.Y;
+			var x = (float)view.X + (float)CompressedLayout.GetHeadlessOffset(view).X;
+			var y = (float)view.Y + (float)CompressedLayout.GetHeadlessOffset(view).Y;
 			var opacity = (float)view.Opacity;
 			var isVisible = view.IsVisible;