From 52aff15ed3db325e5c69fc514acc3fae69dbcac4 Mon Sep 17 00:00:00 2001
From: Nikita Tsukanov <keks9n@gmail.com>
Date: Mon, 29 Jul 2019 13:35:04 +0300
Subject: [PATCH] OverlayLayer is now a glorified Canvas

---
 .../Primitives/OverlayLayer.cs                | 118 +-----------------
 src/Avalonia.Controls/Primitives/PopupHost.cs |  14 +--
 2 files changed, 6 insertions(+), 126 deletions(-)

diff --git a/src/Avalonia.Controls/Primitives/OverlayLayer.cs b/src/Avalonia.Controls/Primitives/OverlayLayer.cs
index 2294c70e9b..231743bd0c 100644
--- a/src/Avalonia.Controls/Primitives/OverlayLayer.cs
+++ b/src/Avalonia.Controls/Primitives/OverlayLayer.cs
@@ -3,102 +3,9 @@ using Avalonia.VisualTree;
 
 namespace Avalonia.Controls.Primitives
 {
-    public class OverlayLayer : Control
+    public class OverlayLayer : Canvas
     {
-        /// <summary>
-        /// Defines the Left attached property.
-        /// </summary>
-        public static readonly AttachedProperty<double> LeftProperty =
-            AvaloniaProperty.RegisterAttached<OverlayLayer, Control, double>("Left", 0);
-
-        /// <summary>
-        /// Defines the Top attached property.
-        /// </summary>
-        public static readonly AttachedProperty<double> TopProperty =
-            AvaloniaProperty.RegisterAttached<OverlayLayer, Control, double>("Top", 0);
-
-        /// <summary>
-        /// Defines the InfiniteAvailableSize attached property.
-        /// </summary>
-        public static readonly AttachedProperty<bool> InfiniteAvailableSizeProperty =
-            AvaloniaProperty.RegisterAttached<OverlayLayer, Control, bool>("InfiniteAvailableSize", false);
-
-
-        static OverlayLayer()
-        {
-            foreach (var p in new []{LeftProperty, TopProperty})
-            {
-                p.Changed.AddClassHandler<Control>((target, e) =>
-                {
-                    if (target.GetVisualParent() is OverlayLayer layer)
-                        layer.InvalidateArrange();
-                });
-            }
-        }
-        
         public Size AvailableSize { get; private set; }
-        
-        /// <summary>
-        /// Gets the value of the Left attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <returns>The control's left coordinate.</returns>
-        public static double GetLeft(AvaloniaObject element)
-        {
-            return element.GetValue(LeftProperty);
-        }
-
-        /// <summary>
-        /// Sets the value of the Left attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <param name="value">The left value.</param>
-        public static void SetLeft(AvaloniaObject element, double value)
-        {
-            element.SetValue(LeftProperty, value);
-        }
-        
-        /// <summary>
-        /// Gets the value of the Top attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <returns>The control's top coordinate.</returns>
-        public static double GetTop(AvaloniaObject element)
-        {
-            return element.GetValue(TopProperty);
-        }
-
-        /// <summary>
-        /// Sets the value of the Top attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <param name="value">The top value.</param>
-        public static void SetTop(AvaloniaObject element, double value)
-        {
-            element.SetValue(TopProperty, value);
-        }
-        
-        /// <summary>
-        /// Gets the value of the Top attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <returns>The control's top coordinate.</returns>
-        public static bool GetInfiniteAvailableSize(AvaloniaObject element)
-        {
-            return element.GetValue(InfiniteAvailableSizeProperty);
-        }
-
-        /// <summary>
-        /// Sets the value of the Top attached property for a control.
-        /// </summary>
-        /// <param name="element">The control.</param>
-        /// <param name="value">The top value.</param>
-        public static void SetInfiniteAvailableSize(AvaloniaObject element, bool value)
-        {
-            element.SetValue(InfiniteAvailableSizeProperty, value);
-        }
-
-        
         public static OverlayLayer GetOverlayLayer(IVisual visual)
         {
             foreach(var v in visual.GetVisualAncestors())
@@ -113,34 +20,13 @@ namespace Avalonia.Controls.Primitives
 
             return null;
         }
-
-        public void Add(Control v)
-        {
-            VisualChildren.Add(v);
-            InvalidateMeasure();
-            InvalidateArrange();
-        }
-
-        public void Remove(Control v) => VisualChildren.Remove(v);
         
-        protected override Size MeasureOverride(Size availableSize)
-        {
-            
-            var infinite = new Size(double.PositiveInfinity, double.PositiveInfinity);
-            foreach (Control v in VisualChildren)
-                v.Measure(GetInfiniteAvailableSize(v) ? infinite : availableSize);
-
-            return new Size();
-        }
-
         protected override Size ArrangeOverride(Size finalSize)
         {
             // We are saving it here since child controls might need to know the entire size of the overlay
             // and Bounds won't be updated in time
             AvailableSize = finalSize;
-            foreach (Control v in VisualChildren)
-                v.Arrange(new Rect(GetLeft(v), GetTop(v), v.DesiredSize.Width, v.DesiredSize.Height));
-            return finalSize;
+            return base.ArrangeOverride(finalSize);
         }
     }
 }
diff --git a/src/Avalonia.Controls/Primitives/PopupHost.cs b/src/Avalonia.Controls/Primitives/PopupHost.cs
index 3d6809c061..a9dcb56ecb 100644
--- a/src/Avalonia.Controls/Primitives/PopupHost.cs
+++ b/src/Avalonia.Controls/Primitives/PopupHost.cs
@@ -12,7 +12,7 @@ using Avalonia.VisualTree;
 
 namespace Avalonia.Controls.Primitives
 {
-    public class PopupHost : Control, IPopupHost, IInteractive, IManagedPopupPositionerPopup
+    public class PopupHost : Decorator, IPopupHost, IInteractive, IManagedPopupPositionerPopup
     {
         private readonly OverlayLayer _overlayLayer;
         private PopupPositionerParameters _positionerParameters = new PopupPositionerParameters();
@@ -28,13 +28,7 @@ namespace Avalonia.Controls.Primitives
 
         public void SetContent(IControl control)
         {
-            if (_content == control)
-                return;
-            if (_content != null)
-                VisualChildren.Remove(_content);
-            _content = control;
-            if (_content != null)
-                VisualChildren.Add(_content);
+            Child = control;
         }
 
         public IVisual VisualRoot => null;
@@ -47,13 +41,13 @@ namespace Avalonia.Controls.Primitives
 
         public void Show()
         {
-            _overlayLayer.Add(this);
+            _overlayLayer.Children.Add(this);
             _shown = true;
         }
 
         public void Hide()
         {
-            _overlayLayer.Remove(this);
+            _overlayLayer.Children.Remove(this);
             _shown = false;
         }