PointerPressed，PointerMoved，PointerReleased関数が思ったように動かない

前提・実現したいこと

筆圧を測定するUWPアプリを作成しています．
画面に表示されている図形をなぞり，なぞっているカーソルの現在の座標値を表示するようにしたい．

発生している問題・エラーメッセージ

表示されている円の中にカーソルを持ってきたときだけしかPointerPressed，PointerMoved，PointerReleased関数が動作していない．円の中以外のアプリの画面にカーソルがあるときも動作してほしい．
プログラミング初心者なため，丁寧に教えていただけると助かります．

該当のソースコード

BlankPage1xaml
1<Page
2    x:Class="UWPApp1.BlankPage1"
3    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
4    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
5    xmlns:local="using:UWPApp1"
6    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
7    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
8    mc:Ignorable="d"
9    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
10
11    <Grid>
12        <Grid PointerPressed="Canvas_PointerPressed">
13            <Grid PointerMoved="Canvas_PointerMoved">
14                <Grid PointerReleased="Canvas_PointerReleased">
15                <Grid PointerMoved="Grid_PointerMoved">
16            <Grid Background="White">
17                <Grid.RowDefinitions>
18                    <RowDefinition Height="Auto"/>
19                    <RowDefinition Height="*"/>
20                </Grid.RowDefinitions>
21                <StackPanel x:Name="HeaderPanel" 
22                    Orientation="Horizontal" 
23                    Grid.Row="0">
24                    <TextBlock x:Name="Header" 
25                        Style="{ThemeResource HeaderTextBlockStyle}" 
26                        Margin="10,0,0,0" SelectionChanged="Header_SelectionChanged" >
27                        <Run Text="描画してください"/><LineBreak/><Run/></TextBlock>
28                    <TextBlock x:Name="text_position" TextWrapping="Wrap" Text="TextBlock" FontSize="24"/>
29                    <TextBlock x:Name="text_isPointerOn" TextWrapping="Wrap" Text="TextBlock" FontSize="24"/>
30
31                </StackPanel>
32
33
34
35
36
37                <Grid x:Name="drawingCanvas" Grid.Row="1" FocusVisualPrimaryBrush="Black">
38                    <Grid.ColumnDefinitions>
39                        <ColumnDefinition Width="0*"/>
40                        <ColumnDefinition/>
41                    </Grid.ColumnDefinitions>
42                    <Grid.FocusVisualSecondaryBrush>
43                        <AcrylicBrush/>
44                    </Grid.FocusVisualSecondaryBrush>
45
46                    <!-- The canvas where we render the replacement text and shapes. -->
47                    <!-- The canvas for ink input. -->
48                    <InkCanvas x:Name="inkCanvas" Grid.ColumnSpan="2" Margin="6,0,-6,0" FocusVisualPrimaryBrush="{x:Null}" FocusVisualSecondaryBrush="{x:Null}" Opacity="0.5" />
49
50                    <!-- The canvas where we render the replacement text and shapes. -->
51                    <Canvas x:Name="recognitionCanvas" Grid.ColumnSpan="2" />
52                    <!-- The canvas for ink input. -->
53
54                </Grid>
55
56            </Grid>
57
58            <Canvas HorizontalAlignment="Left" VerticalAlignment="Top">
59                
60        
61                    
62                        <Ellipse
63                        Stroke="#FF044B0A" FocusVisualPrimaryBrush="{x:Null}" FocusVisualSecondaryBrush="{x:Null}" Margin="132,189,-132,-189" 
64                Height="187" Width="189" RenderTransformOrigin="0.5,0.5" Visibility="Visible" RequestedTheme="Light" Canvas.Left="99" Canvas.Top="162" UseLayoutRounding="False" d:LayoutRounding="Auto" 
65                >
66                            <Ellipse.RenderTransform>
67                                <CompositeTransform Rotation="-0.481"/>
68                            </Ellipse.RenderTransform>
69                        </Ellipse>
70                   
71        
72            </Canvas>
73            <Button Content="Button" Margin="118,63,0,0" VerticalAlignment="Top" RenderTransformOrigin="-3.172,0.297" Click="Button_Click"/>
74            <TextBlock HorizontalAlignment="Left" Margin="121,91,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Height="24"><Run Text="戻るボタン"/><LineBreak/><Run/></TextBlock>
75
76        </Grid>
77        </Grid>
78        </Grid>
79        </Grid>
80    </Grid>
81
82</Page>
83    
84
85

BlankPage1cs
1using System;
2using System.Collections.Generic;
3using System.Diagnostics;
4using System.IO;
5using System.Linq;
6using System.Runtime.InteropServices.WindowsRuntime;
7using Windows.Devices.Input;
8using Windows.Foundation;
9using Windows.Foundation.Collections;
10using Windows.UI.Core;
11using Windows.UI.Input;
12using Windows.UI.Input.Inking;
13using Windows.UI.Xaml;
14using Windows.UI.Xaml.Controls;
15using Windows.UI.Xaml.Controls.Primitives;
16using Windows.UI.Xaml.Data;
17using Windows.UI.Xaml.Input;
18using Windows.UI.Xaml.Media;
19using Windows.UI.Xaml.Navigation;
20
21
22// 空白ページの項目テンプレートについては、https://go.microsoft.com/fwlink/?LinkId=234238 を参照してください
23
24namespace UWPApp1
25{
26    /// <summary>
27    /// それ自体で使用できる空白ページまたはフレーム内に移動できる空白ページ。
28    /// </summary>
29    public sealed partial class BlankPage1 : Page
30    {
31        public BlankPage1()
32        {
33            this.InitializeComponent();
34            // 描画属性を作成する
35            InkDrawingAttributes attributes = new InkDrawingAttributes();
36            attributes.Color = Windows.UI.Colors.Red;   // ペンの色
37            attributes.Size = new Size(5, 2);          // ペンのサイズ
38            attributes.IgnorePressure = true;          // ペンの圧力を使用するかどうか
39            attributes.FitToCurve = false;
40
41            // インクキャンバスに属性を設定する
42            inkCanvas.InkPresenter.UpdateDefaultDrawingAttributes(attributes);
43            // マウスとペンによる描画を許可する
44            inkCanvas.InkPresenter.InputDeviceTypes = Windows.UI.Core.CoreInputDeviceTypes.Mouse | Windows.UI.Core.CoreInputDeviceTypes.Pen;
45        }
46        protected override void OnNavigatedTo(NavigationEventArgs e)
47        {
48            SystemNavigationManager.GetForCurrentView().AppViewBackButtonVisibility = Frame.CanGoBack ?
49                AppViewBackButtonVisibility.Visible : AppViewBackButtonVisibility.Collapsed;
50            SystemNavigationManager.GetForCurrentView().BackRequested += hogehoge;
51            base.OnNavigatedTo(e);
52        }
53        private void hogehoge(object obj, Windows.UI.Core.BackRequestedEventArgs e)
54        {
55            if (Frame.CanGoBack)
56            {
57                Frame.GoBack();
58                if (e != null)
59                    e.Handled = true;
60            }
61        }
62        private void Button_Click(object sender, RoutedEventArgs e)
63        {
64            hogehoge(sender, null);
65        }
66        private void Grid_PointerMoved(object sender, PointerRoutedEventArgs e)
67        {
68            // 0～1の間で筆圧が取れる
69            var pressure = e.GetCurrentPoint(null).Properties.Pressure;
70            Debug.WriteLine(pressure);
71            var p = e.GetCurrentPoint(drawingCanvas);
72            Debug.WriteLine($"({p.Position.X},{p.Position.Y})");
73
74        }
75
76        private void Canvas_PointerPressed(object sender, PointerRoutedEventArgs e)
77        {
78            PointerPoint point = e.GetCurrentPoint(drawingCanvas);
79
80            switch (point.PointerDevice.PointerDeviceType)
81            {
82                case PointerDeviceType.Pen:
83
84                    break;
85                case PointerDeviceType.Mouse:
86                    text_isPointerOn.Text = string.Format("IsPointerOn={0}", true);
87                    break;
88                case PointerDeviceType.Touch:
89                   
90                    break;
91            }
92
93        }
94
95        private void Canvas_PointerMoved(object sender, PointerRoutedEventArgs e)
96        {
97            PointerPoint point = e.GetCurrentPoint(drawingCanvas);
98
99            switch (point.PointerDevice.PointerDeviceType)
100            {
101                case PointerDeviceType.Pen:
102
103                    break;
104                case PointerDeviceType.Mouse:
105                    text_position.Text = string.Format("Position={0},{1}", point.Position.X, point.Position.Y);
106                    break;
107                case PointerDeviceType.Touch:
108                    
109                    break;
110            }
111        }
112
113        private void Canvas_PointerReleased(object sender, PointerRoutedEventArgs e)
114        {
115            PointerPoint point = e.GetCurrentPoint(drawingCanvas);
116
117            switch (point.PointerDevice.PointerDeviceType)
118            {
119                case PointerDeviceType.Pen:
120
121                    break;
122                case PointerDeviceType.Mouse:
123                    text_isPointerOn.Text = string.Format("IsPointerOn={0}", false);
124                    break;
125                case PointerDeviceType.Touch:
126                    
127                    break;
128            }
129        }
130
131        private void Header_SelectionChanged(object sender, RoutedEventArgs e)
132        {
133
134        }
135
136    }
137}
138