Simplify the InPlaceTextEditorAdorner sample

Note: This sample doesn't work on UWP for some weird issue with Popup.PlacementTarget at runtime, even though it should be supported according to the docs.

Author: michael-hawker

components/Adorners/samples/InPlaceTextEditor/InPlaceTextEditorAdornerSample.xaml

@@ -1,4 +1,4 @@
-<!--  Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE file in the project root for more information.  -->
+<!--  Licensed to the .NET Foundation under one or more agreements. The .NET Foundation licenses this file to you under the MIT license. See the LICENSE file in the project root for more information.  -->
 <Page x:Class="AdornersExperiment.Samples.InPlaceTextEditor.InPlaceTextEditorAdornerSample"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -70,13 +70,13 @@
     <StackPanel Spacing="8">
         <TextBlock Text="Click the editable text below to edit:" />
 
-        <!--  We set the DataContext here for our Adorner to retrieve the IEditableObject reference  -->
         <!--  We use TwoWay binding to ensure the updates from the Adorner are reflected in the ViewModel  -->
-        <TextBlock DataContext="{x:Bind ViewModel}"
-                   Text="{x:Bind ViewModel.MyText, Mode=TwoWay}">
+        <TextBlock Text="{x:Bind ViewModel.MyText, Mode=TwoWay}">
             <ui:AdornerLayer.Xaml>
+                <!--  We set the DataContext here for our Adorner to retrieve the IEditableObject reference  -->
                 <!--  Style manually set here as local to example  -->
-                <local:InPlaceTextEditorAdorner Style="{StaticResource DefaultInPlaceTextEditorAdornerStyle}" />
+                <local:InPlaceTextEditorAdorner EditableObject="{x:Bind ViewModel}"
+                                                Style="{StaticResource DefaultInPlaceTextEditorAdornerStyle}" />
             </ui:AdornerLayer.Xaml>
         </TextBlock>
     </StackPanel>

components/Adorners/samples/InPlaceTextEditor/InPlaceTextEditorAdornerSample.xaml.cs

@@ -64,6 +64,21 @@ public void EndEdit()
 /// </summary>
 public sealed partial class InPlaceTextEditorAdorner : Adorner<TextBlock>
 {
+    /// <summary>
+    /// Gets or sets the object being edited.
+    /// </summary>
+    public IEditableObject EditableObject
+    {
+        get { return (IEditableObject)GetValue(EditableObjectProperty); }
+        set { SetValue(EditableObjectProperty, value); }
+    }
+
+    /// <summary>
+    /// Identifies the <see cref="EditableObject"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty EditableObjectProperty =
+        DependencyProperty.Register(nameof(EditableObject), typeof(IEditableObject), typeof(InPlaceTextEditorAdorner), new PropertyMetadata(null));
+
     /// <summary>
     /// Gets or sets whether the popup is open.
     /// </summary>
@@ -108,28 +123,19 @@ protected override void OnDetaching()
 
     private void AdornedElement_Tapped(object sender, TappedRoutedEventArgs e)
     {
-        if (AdornedElement?.DataContext is IEditableObject editableObject)
-        {
-            editableObject.BeginEdit();
-        }
+        EditableObject?.BeginEdit();
         IsPopupOpen = true;
     }
 
     public void ConfirmButton_Click(object sender, RoutedEventArgs e)
     {
-        if (AdornedElement?.DataContext is IEditableObject editableObject)
-        {
-            editableObject.EndEdit();
-        }
+        EditableObject?.EndEdit();
         IsPopupOpen = false;
     }
 
     public void CloseButton_Click(object sender, RoutedEventArgs e)
     {
-        if (AdornedElement?.DataContext is IEditableObject editableObject)
-        {
-            editableObject.CancelEdit();
-        }
+        EditableObject?.CancelEdit();
         IsPopupOpen = false;
     }
 }