Initial import

1 files changed, 88 insertions, 0 deletions

diff --git a/Xamarin.Forms.Platform.Android/RendererPool.cs b/Xamarin.Forms.Platform.Android/RendererPool.cs
new file mode 100644
index 00000000..95a28778
--- /dev/null
+++ b/Xamarin.Forms.Platform.Android/RendererPool.cs
@@ -0,0 +1,88 @@
+using System;
+using System.Collections.Generic;
+
+namespace Xamarin.Forms.Platform.Android
+{
+	public sealed class RendererPool
+	{
+		readonly Dictionary<Type, Stack<IVisualElementRenderer>> _freeRenderers = new Dictionary<Type, Stack<IVisualElementRenderer>>();
+
+		readonly VisualElement _oldElement;
+
+		readonly IVisualElementRenderer _parent;
+
+		public RendererPool(IVisualElementRenderer renderer, VisualElement oldElement)
+		{
+			if (renderer == null)
+				throw new ArgumentNullException("renderer");
+
+			if (oldElement == null)
+				throw new ArgumentNullException("oldElement");
+
+			_oldElement = oldElement;
+			_parent = renderer;
+		}
+
+		public void ClearChildrenRenderers()
+		{
+			if (_parent.Element.LogicalChildren.Count == 0)
+				return;
+			ClearChildrenRenderers(_oldElement);
+		}
+
+		public IVisualElementRenderer GetFreeRenderer(VisualElement view)
+		{
+			if (view == null)
+				throw new ArgumentNullException("view");
+
+			Type rendererType = Registrar.Registered.GetHandlerType(view.GetType()) ?? typeof(ViewRenderer);
+
+			Stack<IVisualElementRenderer> renderers;
+			if (!_freeRenderers.TryGetValue(rendererType, out renderers) || renderers.Count == 0)
+				return null;
+
+			IVisualElementRenderer renderer = renderers.Pop();
+			renderer.SetElement(view);
+			return renderer;
+		}
+
+		void ClearChildrenRenderers(VisualElement view)
+		{
+			if (view == null)
+				return;
+
+			foreach (Element logicalChild in view.LogicalChildren)
+			{
+				var child = logicalChild as VisualElement;
+				if (child != null)
+				{
+					IVisualElementRenderer renderer = Platform.GetRenderer(child);
+					if (renderer == null)
+						continue;
+
+					if (renderer.ViewGroup.Parent != _parent.ViewGroup)
+						continue;
+
+					renderer.ViewGroup.RemoveFromParent();
+
+					Platform.SetRenderer(child, null);
+					PushRenderer(renderer);
+				}
+			}
+
+			if (_parent.ViewGroup.ChildCount != 0)
+				_parent.ViewGroup.RemoveAllViews();
+		}
+
+		void PushRenderer(IVisualElementRenderer renderer)
+		{
+			Type rendererType = renderer.GetType();
+
+			Stack<IVisualElementRenderer> renderers;
+			if (!_freeRenderers.TryGetValue(rendererType, out renderers))
+				_freeRenderers[rendererType] = renderers = new Stack<IVisualElementRenderer>();
+
+			renderers.Push(renderer);
+		}
+	}
+}
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