From 475d120aebd066d11b943080b03e06b0cc78f70d Mon Sep 17 00:00:00 2001
From: Seungkeun Lee <sngn.lee@samsung.com>
Date: Wed, 21 Dec 2016 09:55:45 +0900
Subject: Implement Reusable ViewCell

 - Reusable feature was applied when HasUneventRows is false and the ItemTemplate is not created from the DataTEmplateSelector
 - It means all items has same looks

Change-Id: Iadc1262ff4dcf001b1c767fb479851efa6632c44
---
 .../Cells/ViewCellRenderer.cs                      | 61 ++++++++++++++++++----
 1 file changed, 52 insertions(+), 9 deletions(-)

diff --git a/Xamarin.Forms.Platform.Tizen/Cells/ViewCellRenderer.cs b/Xamarin.Forms.Platform.Tizen/Cells/ViewCellRenderer.cs
index 69065c8a..63287786 100644
--- a/Xamarin.Forms.Platform.Tizen/Cells/ViewCellRenderer.cs
+++ b/Xamarin.Forms.Platform.Tizen/Cells/ViewCellRenderer.cs
@@ -5,6 +5,7 @@ namespace Xamarin.Forms.Platform.Tizen
 {
 	public class ViewCellRenderer : CellRenderer
 	{
+		readonly Dictionary<EvasObject, ViewCell> _cacheCandidate = new Dictionary<EvasObject, ViewCell>();
 		public ViewCellRenderer() : base("full")
 		{
 			MainContentPart = "elm.swallow.content";
@@ -12,21 +13,42 @@ namespace Xamarin.Forms.Platform.Tizen
 
 		protected string MainContentPart { get; set; }
 
+		protected override EvasObject OnReusableContent(Cell cell, string part, EvasObject old)
+		{
+			if (_cacheCandidate.ContainsKey(old))
+			{
+				var viewCell = _cacheCandidate[old];
+				var widget = (old as Widget);
+				if (widget != null)
+					widget.IsEnabled = true;
+				viewCell.BindingContext = cell.BindingContext;
+				return old;
+			}
+			return null;
+		}
+
 		protected override EvasObject OnGetContent(Cell cell, string part)
 		{
 			if (part == MainContentPart)
 			{
-				var viewCell = cell as ViewCell;
-				if (viewCell != null)
-				{
-					var renderer = Platform.GetOrCreateRenderer(viewCell.View);
-					int height = (int)viewCell.RenderHeight;
-					height = height <= 0 ? FindCellContentHeight(viewCell) : height;
+				var viewCell = (ViewCell)cell;
 
-					renderer.NativeView.MinimumHeight = height;
-					return renderer.NativeView;
+				var listView = viewCell?.RealParent as ListView;
+
+				// It is a condition for reusable the cell
+				if (listView != null &&
+					listView.HasUnevenRows == false &&
+					!(listView.ItemTemplate is DataTemplateSelector))
+				{
+					return CreateReusableContent(viewCell);
 				}
-				return null;
+
+				var renderer = Platform.GetOrCreateRenderer(viewCell.View);
+				int height = (int)viewCell.RenderHeight;
+				height = height > 0 ? height : FindCellContentHeight(viewCell);
+
+				renderer.NativeView.MinimumHeight = height;
+				return renderer.NativeView;
 			}
 			return null;
 		}
@@ -39,5 +61,26 @@ namespace Xamarin.Forms.Platform.Tizen
 			}
 			return base.OnCellPropertyChanged(cell, property, realizedView);
 		}
+
+		EvasObject CreateReusableContent(ViewCell viewCell)
+		{
+			var listView = viewCell.RealParent as ListView;
+			ViewCell duplicatedCell = (ViewCell)listView.ItemTemplate.CreateContent();
+			duplicatedCell.BindingContext = viewCell.BindingContext;
+			duplicatedCell.Parent = listView;
+
+			var renderer = Platform.GetOrCreateRenderer(duplicatedCell.View);
+			int height = (int)duplicatedCell.RenderHeight;
+			height = height > 0 ? height : FindCellContentHeight(duplicatedCell);
+			renderer.NativeView.MinimumHeight = height;
+
+			_cacheCandidate[renderer.NativeView] = duplicatedCell;
+			renderer.NativeView.Deleted += (sender, e) =>
+			{
+				_cacheCandidate.Remove((EvasObject)sender);
+			};
+
+			return renderer.NativeView;
+		}
 	}
 }
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