Refactor layout update code

 - A small refactoring
 - In OnBatchCommitted, Only update the Element itself location, not update children
   Because it is enough
 - Prevent duplicate update
 - Globally applied IgnoreBatchCommitted was changed to locally and re-named
 - Fixed rotation issue

Change-Id: I32b57317169d81d7ad6e45f0b52eb2a8f1d861fa

3 files changed, 37 insertions, 69 deletions

diff --git a/Xamarin.Forms.Platform.Tizen/Native/Box.cs b/Xamarin.Forms.Platform.Tizen/Native/Box.cs
index 9bd7bad9..2f551902 100644
--- a/Xamarin.Forms.Platform.Tizen/Native/Box.cs
+++ b/Xamarin.Forms.Platform.Tizen/Native/Box.cs
@@ -52,10 +52,7 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 				LayoutUpdated(this, new LayoutEventArgs()
 					{
 						HasChanged = g != _previousGeometry,
-						X = g.X,
-						Y = g.Y,
-						Width = g.Width,
-						Height = g.Height,
+						Geometry = g,
 					}
 				);
 			}
diff --git a/Xamarin.Forms.Platform.Tizen/Native/LayoutEventArgs.cs b/Xamarin.Forms.Platform.Tizen/Native/LayoutEventArgs.cs
index 6668f8d7..060a1212 100644
--- a/Xamarin.Forms.Platform.Tizen/Native/LayoutEventArgs.cs
+++ b/Xamarin.Forms.Platform.Tizen/Native/LayoutEventArgs.cs
@@ -1,4 +1,5 @@
 using System;
+using ElmSharp;
 
 namespace Xamarin.Forms.Platform.Tizen.Native
 {
@@ -17,39 +18,12 @@ namespace Xamarin.Forms.Platform.Tizen.Native
 		}
 
 		/// <summary>
-		/// X coordinate of the layout area, relative to the main window.
+		/// Geometry of the layout area, absolute coordinate
 		/// </summary>
-		public int X
+		public Rect Geometry
 		{
 			get;
-			internal set;
-		}
-
-		/// <summary>
-		/// Y coordinate of the layout area, relative to the main window.
-		/// </summary>
-		public int Y
-		{
-			get;
-			internal set;
-		}
-
-		/// <summary>
-		/// Width of the layout area.
-		/// </summary>
-		public int Width
-		{
-			get;
-			internal set;
-		}
-
-		/// <summary>
-		/// Height of the layout area.
-		/// </summary>
-		public int Height
-		{
-			get;
-			internal set;
+			set;
 		}
 	}
 }
diff --git a/Xamarin.Forms.Platform.Tizen/Renderers/VisualElementRenderer.cs b/Xamarin.Forms.Platform.Tizen/Renderers/VisualElementRenderer.cs
index 73e8c64f..37e2a036 100644
--- a/Xamarin.Forms.Platform.Tizen/Renderers/VisualElementRenderer.cs
+++ b/Xamarin.Forms.Platform.Tizen/Renderers/VisualElementRenderer.cs
@@ -44,6 +44,8 @@ namespace Xamarin.Forms.Platform.Tizen
 
 		HashSet<string> _batchedProperties = new HashSet<string>();
 
+		int _layoutCallback = 0;
+
 		/// <summary>
 		/// Default constructor.
 		/// </summary>
@@ -209,10 +211,13 @@ namespace Xamarin.Forms.Platform.Tizen
 
 		public void UpdateNativeGeometry()
 		{
-			var x = ComputeAbsoluteX(Element);
-			var y = ComputeAbsoluteY(Element);
-			NativeView.Geometry = new Rectangle(x, y, Element.Width, Element.Height).ToPixel();
-			ApplyTransformation();
+			var updatedGeometry = new Rectangle(ComputeAbsolutePoint(Element), new Size(Element.Width, Element.Height)).ToPixel();
+
+			if (NativeView.Geometry != updatedGeometry)
+			{
+				NativeView.Geometry = updatedGeometry;
+				ApplyTransformation();
+			}
 		}
 
 		void IVisualElementRenderer.SetElement(VisualElement element)
@@ -250,14 +255,15 @@ namespace Xamarin.Forms.Platform.Tizen
 		protected virtual void UpdateLayout()
 		{
 			// we're updating the coordinates of native control only if they were modified
-			// via Xamarin (Settings.IgnoreBatchCommitted is set to false);
+			// via Xamarin (IsNativeLayouting() returns false);
 			// otherwise native control is already in the right place
-			if (!Settings.IgnoreBatchCommitted && null != NativeView)
+			if (!IsNativeLayouting() && null != NativeView)
 			{
 				UpdateNativeGeometry();
 			}
 
 			// we're updating just immediate children
+			// To update the relative postion of children
 			var logicalChildren = (Element as IElementController).LogicalChildren;
 			foreach (var child in logicalChildren)
 			{
@@ -291,9 +297,7 @@ namespace Xamarin.Forms.Platform.Tizen
 
 					Element.FocusChangeRequested -= OnFocusChangeRequested;
 
-					Settings.StartIgnoringBatchCommitted();
 					Element.Layout(new Rectangle(0, 0, -1, -1));
-					Settings.StopIgnoringBatchCommitted();
 
 					var logicalChildren = (Element as IElementController).LogicalChildren;
 					foreach (var child in logicalChildren)
@@ -334,9 +338,7 @@ namespace Xamarin.Forms.Platform.Tizen
 
 				e.OldElement.FocusChangeRequested -= OnFocusChangeRequested;
 
-				Settings.StartIgnoringBatchCommitted();
 				Element.Layout(new Rectangle(0, 0, -1, -1));
-				Settings.StopIgnoringBatchCommitted();
 
 				var controller = e.OldElement as IElementController;
 				if (controller != null && controller.EffectControlProvider == this)
@@ -460,9 +462,9 @@ namespace Xamarin.Forms.Platform.Tizen
 		{
 			if (_flags.HasFlag(VisualElementRendererFlags.NeedsLayout))
 			{
-				if (!Settings.IgnoreBatchCommitted)
+				if (!IsNativeLayouting())
 				{
-					UpdateLayout();
+					UpdateNativeGeometry();
 					// UpdateLayout already updates transformation, clear NeedsTranformation flag then
 					_flags &= ~VisualElementRendererFlags.NeedsTransformation;
 				}
@@ -548,19 +550,21 @@ namespace Xamarin.Forms.Platform.Tizen
 
 		protected void DoLayout(Native.LayoutEventArgs e)
 		{
-			Settings.StartIgnoringBatchCommitted();
-
-			Element.Layout(new Rectangle(Element.X, Element.Y, Forms.ConvertToScaledDP(e.Width), Forms.ConvertToScaledDP(e.Height)));
+			EnterNativeLayoutCallback();
 			if (e.HasChanged)
 			{
+				var bound = e.Geometry.ToDP();
+				bound.X = Element.X;
+				bound.Y = Element.Y;
+				Element.Layout(bound);
 				UpdateLayout();
 			}
-			Settings.StopIgnoringBatchCommitted();
+			LeaveNativeLayoutCallback();
 		}
 
 		protected virtual Size MinimumSize()
 		{
-			return new Size();
+			return new ESize(NativeView.MinimumWidth, NativeView.MinimumHeight).ToDP();
 		}
 
 		/// <summary>
@@ -606,6 +610,11 @@ namespace Xamarin.Forms.Platform.Tizen
 			return e.Y + (e.RealParent is VisualElement ? Forms.ConvertToScaledDP(Platform.GetRenderer(e.RealParent).NativeView.Geometry.Y) : 0.0);
 		}
 
+		static Point ComputeAbsolutePoint(VisualElement e)
+		{
+			return new Point(ComputeAbsoluteX(e), ComputeAbsoluteY(e));
+		}
+
 		/// <summary>
 		/// Handles focus events.
 		/// </summary>
@@ -995,7 +1004,6 @@ namespace Xamarin.Forms.Platform.Tizen
 				NativeView.EvasMap = map;
 			}
 		}
-
 		EFocusDirection ConvertToNativeFocusDirection(string direction) {
 			if (direction == XFocusDirection.Back) return EFocusDirection.Previous;
 			if (direction == XFocusDirection.Forward) return EFocusDirection.Next;
@@ -1006,29 +1014,18 @@ namespace Xamarin.Forms.Platform.Tizen
 
 			return EFocusDirection.Next;
 		}
-	}
 
-	internal static class Settings
-	{
-		static int s_ignoreCount = 0;
-
-		public static bool IgnoreBatchCommitted
+		void EnterNativeLayoutCallback()
 		{
-			get
-			{
-				return s_ignoreCount != 0;
-			}
+			_layoutCallback++;
 		}
-
-		public static void StartIgnoringBatchCommitted()
+		void LeaveNativeLayoutCallback()
 		{
-			++s_ignoreCount;
+			_layoutCallback--;
 		}
-
-		public static void StopIgnoringBatchCommitted()
+		bool IsNativeLayouting()
 		{
-			Debug.Assert(s_ignoreCount > 0);
-			--s_ignoreCount;
+			return _layoutCallback > 0;
 		}
 	}
 }