ListViewRenderer now properly lays out custom cell views. As a result of this fix the renderer will now respect row heights set in Xamarin.Forms and should support lists with uneven cell heights.

Ooui.Forms/Renderers/ListViewRenderer.cs

@@ -11,7 +11,17 @@ namespace Ooui.Forms.Renderers
 {
     public class ListViewRenderer : ViewRenderer<ListView, List>
     {
+        const int DefaultRowHeight = 44;
         private bool _disposed;
+        IVisualElementRenderer _prototype;
+
+        int _rowHeight;
+
+        public int RowHeight
+        {
+            get => _rowHeight;
+            set => _rowHeight = value;
+        }
 
         public ListViewRenderer ()
         {
@@ -32,6 +42,10 @@ namespace Ooui.Forms.Renderers
                     var list = new List ();
                     list.Style.Overflow = "scroll";
                     list.Style.Padding = "0";
+                    // Make the list element positioned so child elements will
+                    // be positioned relative to it. This will allow the list
+                    // to scroll properly.
+                    list.Style.Position = "relative";
 
                     SetNativeControl (list);
                 }
@@ -40,6 +54,8 @@ namespace Ooui.Forms.Renderers
                 templatedItems.CollectionChanged += OnCollectionChanged;
                 e.NewElement.ScrollToRequested += ListView_ScrollToRequested;
 
+                UpdateRowHeight();
+
                 UpdateItems ();
                 UpdateBackgroundColor ();
             }
@@ -121,11 +137,22 @@ namespace Ooui.Forms.Renderers
             }
             else {
                 var i = 0;
+                double offset = 0;
                 foreach (var item in items) {
                     var li = listItems[i];
+                    var nativeCell = items[i];
                     var children = li.Children;
                     var rv = children.Count > 0 ? children[0] as CellElement : null;
                     var cell = GetCell (item, rv);
+                    var height = CalculateHeightForCell(nativeCell);
+                    li.Style.Height = height;
+                    var viewCell = (ViewCell)cell.Cell;
+                    if (viewCell != null && viewCell.View != null)
+                    {
+                        var rect = new Rectangle(0, offset, Element.Width, height);
+                        Layout.LayoutChildIntoBoundingRegion(viewCell.View, rect);
+                    }
+                    offset += height;
                     if (rv == null) {
                         li.AppendChild (cell);
                     }
@@ -161,6 +188,56 @@ namespace Ooui.Forms.Renderers
             }
         }
 
+        void UpdateRowHeight()
+        {
+            var rowHeight = Element.RowHeight;
+            if (Element.HasUnevenRows && rowHeight == -1)
+                RowHeight = -1;
+            else
+                RowHeight = rowHeight <= 0 ? DefaultRowHeight : rowHeight;
+        }
+
+        internal double CalculateHeightForCell(Cell cell)
+        {  
+            if (!Element.HasUnevenRows)
+            {
+                return RowHeight;
+            } 
+            else 
+            {
+                var viewCell = cell as ViewCell;
+                if (viewCell != null && viewCell.View != null)
+                {
+                    var target = viewCell.View;
+                    if (_prototype == null)
+                        _prototype = Platform.CreateRenderer(target);
+                    else
+                        _prototype.SetElement(target);
+
+                    Platform.SetRenderer(target, _prototype);
+
+                    var req = target.Measure(Element.Width, double.PositiveInfinity, MeasureFlags.IncludeMargins);
+
+                    target.ClearValue(Platform.RendererProperty);
+                    foreach (Xamarin.Forms.Element descendant in target.Descendants())
+                    {
+                        IVisualElementRenderer renderer = Platform.GetRenderer(descendant as VisualElement);
+
+                        // Clear renderer from descendent; this will not happen in Dispose as normal because we need to
+                        // unhook the Element from the renderer before disposing it.
+                        descendant.ClearValue(Platform.RendererProperty);
+                        renderer?.Dispose();
+                        renderer = null;
+                    }
+
+                    var height = req.Request.Height;
+                    return height > 1 ? height : DefaultRowHeight;
+                }
+                var renderHeight = cell.RenderHeight;
+                return renderHeight > 0 ? renderHeight : DefaultRowHeight;
+            }
+        }
+
         void UpdateBackgroundColor ()
         {
             if (Control == null)