Draw DropDown selected content using VisualBrush

If content is a control. Fixes #87.

src/Perspex.Controls/DropDown.cs

@@ -10,10 +10,12 @@ namespace Perspex.Controls
     using System.Linq;
     using Generators;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Shapes;
     using Perspex.Controls.Templates;
     using Perspex.Input;
     using Perspex.Layout;
-    using VisualTree;
+    using Perspex.Media;
+    using Perspex.VisualTree;
 
     public class DropDown : SelectingItemsControl, IContentControl
     {
@@ -29,16 +31,19 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<bool> IsDropDownOpenProperty =
             PerspexProperty.Register<DropDown, bool>("IsDropDownOpen");
 
+        public static readonly PerspexProperty<object> SelectionBoxItemProperty =
+            PerspexProperty.Register<DropDown, object>("SelectionBoxItem");
+
         private Popup popup;
 
         static DropDown()
         {
             FocusableProperty.OverrideDefaultValue<DropDown>(true);
+            SelectedItemProperty.Changed.AddClassHandler<DropDown>(x => x.SelectedItemChanged);
         }
 
         public DropDown()
         {
-            this.GetObservableWithHistory(ContentProperty).Subscribe(this.SetContentParent);
             this.Bind(ContentProperty, this.GetObservable(DropDown.SelectedItemProperty));
         }
 
@@ -66,6 +71,12 @@ namespace Perspex.Controls
             set { this.SetValue(IsDropDownOpenProperty, value); }
         }
 
+        public object SelectionBoxItem
+        {
+            get { return this.GetValue(SelectionBoxItemProperty); }
+            set { this.SetValue(SelectionBoxItemProperty, value); }
+        }
+
         protected override IItemContainerGenerator CreateItemContainerGenerator()
         {
             return new ItemContainerGenerator<ListBoxItem>(this);
@@ -126,19 +137,27 @@ namespace Perspex.Controls
             }
         }
 
-        private void SetContentParent(Tuple<object, object> change)
+        private void SelectedItemChanged(PerspexPropertyChangedEventArgs e)
         {
-            var control1 = change.Item1 as Control;
-            var control2 = change.Item2 as Control;
+            var control = e.NewValue as IControl;
 
-            if (control1 != null)
+            if (control != null)
             {
-                ((ISetLogicalParent)control1).SetParent(null);
+                this.SelectionBoxItem = new Rectangle
+                {
+                    Width = control.DesiredSize.Width,
+                    Height = control.DesiredSize.Height,
+                    Fill = new VisualBrush
+                    {
+                        Visual = control,
+                        Stretch = Stretch.None,
+                        AlignmentX = AlignmentX.Left,
+                    }
+                };
             }
-
-            if (control2 != null)
+            else
             {
-                ((ISetLogicalParent)control2).SetParent(this);
+                this.SelectionBoxItem = e.NewValue;
             }
         }
     }

src/Perspex.SceneGraph/Rendering/RendererBase.cs

@@ -35,10 +35,11 @@ namespace Perspex.Rendering
         public virtual void Render(IVisual visual, IPlatformHandle handle)
         {
             this.Render(visual, handle, Matrix.Identity);
+            ++this.RenderCount;
         }
 
         /// <summary>
-        /// Renders the specified visual with the specified transform.
+        /// Renders the specified visual with the specified transform and clip.
         /// </summary>
         /// <param name="visual">The visual to render.</param>
         /// <param name="handle">An optional platform-specific handle.</param>
@@ -51,8 +52,6 @@ namespace Perspex.Rendering
             {
                 this.Render(visual, context, Matrix.Identity, transform);
             }
-
-            ++this.RenderCount;
         }
 
         /// <summary>

src/Perspex.Themes.Default/DropDownStyle.cs

@@ -93,7 +93,7 @@ namespace Perspex.Themes.Default
                         {
                             Name = "contentControl",
                             Margin = new Thickness(3),
-                            [~ContentControl.ContentProperty] = control[~DropDown.ContentProperty],
+                            [~ContentControl.ContentProperty] = control[~DropDown.SelectionBoxItemProperty],
                             [~ContentControl.HorizontalAlignmentProperty] = control[~DropDown.HorizontalContentAlignmentProperty],
                             [~ContentControl.VerticalAlignmentProperty] = control[~DropDown.VerticalContentAlignmentProperty],
                         },
@@ -129,7 +129,7 @@ namespace Perspex.Themes.Default
                                 Padding = new Thickness(4),
                                 Child = new ItemsPresenter
                                 {
-                                    [~ListBox.ItemsProperty] = control[~DropDown.ItemsProperty],
+                                    [~ItemsPresenter.ItemsProperty] = control[~DropDown.ItemsProperty],
                                 }
                             },
                             PlacementTarget = control,

src/Perspex.Themes.Default/ListBoxItemStyle.cs

@@ -43,8 +43,7 @@ namespace Perspex.Themes.Default
                 {
                     Setters = new[]
                     {
-                        new Setter(ListBoxItem.BackgroundProperty, new SolidColorBrush(0xff086f9e)),
-                        new Setter(ListBoxItem.ForegroundProperty, Brushes.White),
+                        new Setter(ListBoxItem.BackgroundProperty, new SolidColorBrush(0xffd0d0d0)),
                     },
                 },
             });