Reuse cell views in ListViews

Fixes #132

Ooui.Forms/Cells/CellRenderer.cs

@@ -14,7 +14,7 @@ namespace Ooui.Forms.Cells
 
         public virtual CellView GetCell(Cell item, CellView reusableView, List listView)
         {
-            var nativeCell = reusableView as CellView ?? GetCellInstance(item);
+            var nativeCell = reusableView ?? GetCellInstance (item);
 
             nativeCell.Cell = item;
 
@@ -46,14 +46,12 @@ namespace Ooui.Forms.Cells
 
         protected void UpdateBackground(CellView tableViewCell, Cell cell)
         {
-            var defaultColor = Xamarin.Forms.Color.White.ToOouiColor();
+            var backgroundColor = Xamarin.Forms.Color.Default;
-            Color backgroundColor = defaultColor;
 
-            if (cell.RealParent is VisualElement element)
+            if (backgroundColor == Xamarin.Forms.Color.Default && cell.RealParent is VisualElement element)
-                backgroundColor = element.BackgroundColor ==
+                backgroundColor = element.BackgroundColor;
-                    Xamarin.Forms.Color.Default ? backgroundColor : element.BackgroundColor.ToOouiColor();
             
-            tableViewCell.Style.BackgroundColor = backgroundColor;
+            tableViewCell.Style.BackgroundColor = backgroundColor.ToOouiColor (Xamarin.Forms.Color.White);
         }
 
         protected void WireUpForceUpdateSizeRequested(Cell cell, CellView nativeCell)

Ooui.Forms/Extensions/ColorExtensions.cs

@@ -23,5 +23,12 @@ namespace Ooui.Forms.Extensions
                 return defaultColor.ToOouiColor ();
             return color.ToOouiColor ();
         }
+
+        public static Color ToOouiColor (this Xamarin.Forms.Color color, Ooui.Color defaultColor)
+        {
+            if (color == Xamarin.Forms.Color.Default)
+                return defaultColor;
+            return color.ToOouiColor ();
+        }
 	}
 }

Ooui.Forms/Renderers/ListViewRenderer.cs

@@ -5,40 +5,35 @@ using System.ComponentModel;
 using System.Linq;
 using Xamarin.Forms;
 using Xamarin.Forms.Internals;
+using Ooui.Forms.Cells;
 
 namespace Ooui.Forms.Renderers
 {
     public class ListViewRenderer : ViewRenderer<ListView, List>
     {
         private bool _disposed;
-        private List _listView;
-        private List<ListItem> _cells;
 
         public ListViewRenderer ()
         {
-            _cells = new List<ListItem>();
         }
 
         ITemplatedItemsView<Cell> TemplatedItemsView => Element;
 
         protected override void OnElementChanged (ElementChangedEventArgs<ListView> e)
         {
-            if (e.OldElement != null) 
+            if (e.OldElement != null) {
-            {
                 var templatedItems = TemplatedItemsView.TemplatedItems;
                 templatedItems.CollectionChanged -= OnCollectionChanged;
                 e.OldElement.ScrollToRequested -= ListView_ScrollToRequested;
             }
 
-            if (e.NewElement != null)
+            if (e.NewElement != null) {
-            {
+                if (Control == null) {
-                if (Control == null)
+                    var list = new List ();
-                {
+                    list.Style.Overflow = "scroll";
-                    _listView = new List();
+                    list.Style.Padding = "0";
-                    _listView.Style.Overflow = "scroll";
-                    _listView.Style.Padding = "0";
 
-                    SetNativeControl(_listView);
+                    SetNativeControl (list);
                 }
 
                 var templatedItems = TemplatedItemsView.TemplatedItems;
@@ -56,7 +51,7 @@ namespace Ooui.Forms.Renderers
         {
             base.OnElementPropertyChanged (sender, e);
 
-            if (e.PropertyName == ListView.ItemsSourceProperty.PropertyName)
+            if (e.PropertyName == ItemsView<Cell>.ItemsSourceProperty.PropertyName)
                 UpdateItems ();
         }
 
@@ -66,11 +61,9 @@ namespace Ooui.Forms.Renderers
 
             base.Dispose (disposing);
 
-            if (disposing && !_disposed) 
+            if (disposing && !_disposed) {
-            {
 
-                if (Element != null) 
+                if (Element != null) {
-                {
                     var templatedItems = TemplatedItemsView.TemplatedItems;
                     templatedItems.CollectionChanged -= OnCollectionChanged;
                     Element.ScrollToRequested -= ListView_ScrollToRequested;
@@ -87,59 +80,66 @@ namespace Ooui.Forms.Renderers
 
         private void UnsubscribeCellClicks ()
         {
-			foreach (var c in _cells)
+            if (Control == null)
-			{
+                return;
-				c.Click -= ListItem_Click;
+            foreach (var c in Control.Children) {
+                if (c is Element e)
+                    e.Click -= ListItem_Click;
             }
         }
 
         private void UpdateItems ()
         {
-			UnsubscribeCellClicks();
+            if (Control == null)
-            _cells.Clear();
+                return;
 
-            foreach (var child in _listView.Children) 
+            var listItems = Control.Children.OfType<ListItem> ().ToList ();
-            {
-                _listView.RemoveChild (child);
-            }
 
             var items = TemplatedItemsView.TemplatedItems;
 
-            if (!items.Any())
+            if (listItems.Count > items.Count) {
-            {
+                for (var i = items.Count; i < listItems.Count; i++) {
-                return;
+                    listItems[i].Click -= ListItem_Click;
+                    Control.RemoveChild (listItems[i]);
+                }
+                listItems.RemoveRange (items.Count, listItems.Count - items.Count);
+            }
+            if (listItems.Count < items.Count) {
+                for (var i = listItems.Count; i < items.Count; i++) {
+                    var li = new ListItem ();
+                    li.Style["list-style-type"] = "none";
+                    li.Click += ListItem_Click;
+                    Control.AppendChild (li);
+                    listItems.Add (li);
+                }
             }
 
             bool grouping = Element.IsGroupingEnabled;
 
-            if (grouping)
+            if (grouping) {
+                // Not Implemented
+            }
+            else {
+                var i = 0;
+                foreach (var item in items) {
+                    var li = listItems[i];
+                    var children = li.Children;
+                    var rv = children.Count > 0 ? children[0] as CellView : null;
+                    var cell = GetCell (item, rv);
+                    if (rv == null) {
+                        li.AppendChild (cell);
+                    }
+                    i++;
+                }
+            }
+        }
+
+        void ListItem_Click (object sender, TargetEventArgs e)
         {
+            if (Control == null)
                 return;
-            }
-
-            foreach (var item in items)
-            {
-                var cell = GetCell(item);
-
-                var listItem = new ListItem();
-                listItem.Style["list-style-type"] = "none";
-
-                listItem.AppendChild(cell);
-                listItem.Click += ListItem_Click;
-
-                _cells.Add(listItem);
-            }
-
-            foreach (var cell in _cells)
-            {
-                _listView.AppendChild(cell);
-            }
-        }
-
-        private void ListItem_Click(object sender, TargetEventArgs e)
-        {
             var it = (ListItem)sender;
-            var ndx = _cells.IndexOf(it);
+            var ndx = Control.Children.IndexOf (it);
             Element.NotifyRowTapped (ndx, null);
         }
 
@@ -161,19 +161,21 @@ namespace Ooui.Forms.Renderers
             }
         }
 
-        private void UpdateBackgroundColor()
+        void UpdateBackgroundColor ()
         {
-            var backgroundColor = Element.BackgroundColor.ToOouiColor();
+            if (Control == null)
+                return;
             
-            _listView.Style.BackgroundColor = backgroundColor;
+            var backgroundColor = Element.BackgroundColor.ToOouiColor (Xamarin.Forms.Color.White);
+
+            Control.Style.BackgroundColor = backgroundColor;
         }
 
-        private Div GetCell(Cell cell)
+        CellView GetCell (Cell cell, CellView reusableView)
         {
-            var renderer =
+            var renderer = (Cells.CellRenderer)Registrar.Registered.GetHandlerForObject<IRegisterable> (cell);
-                (Cells.CellRenderer)Registrar.Registered.GetHandler<IRegisterable>(cell.GetType());
 
-            var realCell = renderer.GetCell(cell, null, _listView);
+            var realCell = renderer.GetCell (cell, reusableView, Control);
 
             return realCell;
         }

Ooui/Client.js

@@ -1,6 +1,6 @@
 // Ooui v1.0.0
 
-var debug = false;
+var debug = true;
 
 const nodes = {};
 const hasText = {};