Idle state loading for calendar.

Wino.Calendar.ViewModels/CalendarPageViewModel.cs

@@ -195,6 +195,8 @@ namespace Wino.Calendar.ViewModels
 
         private async Task InsertDayRangeModelAsync(DayRangeRenderModel dayRangeRenderModel, int index)
         {
+            if (dayRangeRenderModel == null) return;
+
             dayRangeRenderModel.CalendarDayEventCollectionUpdated -= EventsUpdatedInDayHeader;
             dayRangeRenderModel.CalendarDayEventCollectionUpdated += EventsUpdatedInDayHeader;
 
@@ -206,6 +208,8 @@ namespace Wino.Calendar.ViewModels
 
         private async Task RemoveDayRangeModelAsync(DayRangeRenderModel dayRangeRenderModel)
         {
+            if (dayRangeRenderModel == null) return;
+
             dayRangeRenderModel.CalendarDayEventCollectionUpdated -= EventsUpdatedInDayHeader;
             dayRangeRenderModel.UnregisterAll();
 
@@ -217,10 +221,18 @@ namespace Wino.Calendar.ViewModels
 
         private async Task ClearDayRangeModelsAsync()
         {
-            while (DayRanges.Count > 0)
+            // Unregister all events and clear the list directly.
+
+            foreach (var dayRangeModel in DayRanges)
             {
-                await RemoveDayRangeModelAsync(DayRanges[0]);
+                dayRangeModel.CalendarDayEventCollectionUpdated -= EventsUpdatedInDayHeader;
+                dayRangeModel.UnregisterAll();
             }
+
+            await ExecuteUIThread(() =>
+            {
+                DayRanges.Clear();
+            });
         }
 
         private async Task RenderDatesAsync(CalendarInitInitiative calendarInitInitiative,

Wino.Calendar/Controls/WinoCalendarControl.cs

@@ -10,6 +10,7 @@ namespace Wino.Calendar.Controls
     public class WinoCalendarControl : Control
     {
         private const string PART_WinoFlipView = nameof(PART_WinoFlipView);
+        private const string PART_IdleGrid = nameof(PART_IdleGrid);
 
         public event EventHandler<TimelineCellSelectedArgs> TimelineCellSelected;
         public event EventHandler<TimelineCellUnselectedArgs> TimelineCellUnselected;
@@ -20,6 +21,7 @@ namespace Wino.Calendar.Controls
         public static readonly DependencyProperty SelectedFlipViewIndexProperty = DependencyProperty.Register(nameof(SelectedFlipViewIndex), typeof(int), typeof(WinoCalendarControl), new PropertyMetadata(-1));
         public static readonly DependencyProperty SelectedFlipViewDayRangeProperty = DependencyProperty.Register(nameof(SelectedFlipViewDayRange), typeof(DayRangeRenderModel), typeof(WinoCalendarControl), new PropertyMetadata(null));
         public static readonly DependencyProperty ActiveCanvasProperty = DependencyProperty.Register(nameof(ActiveCanvas), typeof(WinoDayTimelineCanvas), typeof(WinoCalendarControl), new PropertyMetadata(null, new PropertyChangedCallback(OnActiveCanvasChanged)));
+        public static readonly DependencyProperty IsFlipIdleProperty = DependencyProperty.Register(nameof(IsFlipIdle), typeof(bool), typeof(WinoCalendarControl), new PropertyMetadata(true, new PropertyChangedCallback(OnIdleStateChanged)));
 
         public DayRangeRenderModel SelectedFlipViewDayRange
         {
@@ -33,6 +35,12 @@ namespace Wino.Calendar.Controls
             set { SetValue(ActiveCanvasProperty, value); }
         }
 
+        public bool IsFlipIdle
+        {
+            get { return (bool)GetValue(IsFlipIdleProperty); }
+            set { SetValue(IsFlipIdleProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets the collection of day ranges to render.
         /// Each day range usually represents a week, but it may support other ranges.
@@ -52,6 +60,7 @@ namespace Wino.Calendar.Controls
         #endregion
 
         private WinoCalendarFlipView InternalFlipView;
+        private Grid IdleGrid;
 
         public WinoCalendarControl()
         {
@@ -59,6 +68,14 @@ namespace Wino.Calendar.Controls
             SizeChanged += CalendarSizeChanged;
         }
 
+        private static void OnIdleStateChanged(DependencyObject calendar, DependencyPropertyChangedEventArgs e)
+        {
+            if (calendar is WinoCalendarControl calendarControl)
+            {
+                calendarControl.UpdateIdleState();
+            }
+        }
+
         private static void OnActiveCanvasChanged(DependencyObject calendar, DependencyPropertyChangedEventArgs e)
         {
             if (calendar is WinoCalendarControl calendarControl)
@@ -120,6 +137,15 @@ namespace Wino.Calendar.Controls
             base.OnApplyTemplate();
 
             InternalFlipView = GetTemplateChild(PART_WinoFlipView) as WinoCalendarFlipView;
+            IdleGrid = GetTemplateChild(PART_IdleGrid) as Grid;
+
+            UpdateIdleState();
+        }
+
+        private void UpdateIdleState()
+        {
+            InternalFlipView.Visibility = IsFlipIdle ? Visibility.Collapsed : Visibility.Visible;
+            IdleGrid.Visibility = IsFlipIdle ? Visibility.Visible : Visibility.Collapsed;
         }
 
         private void ActiveTimelineCellUnselected(object sender, TimelineCellUnselectedArgs e)

Wino.Calendar/Controls/WinoCalendarFlipView.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Specialized;
 using System.Linq;
 using System.Threading.Tasks;
 using CommunityToolkit.WinUI;
@@ -11,17 +12,33 @@ namespace Wino.Calendar.Controls
 {
     public class WinoCalendarFlipView : CustomCalendarFlipView
     {
+        public static readonly DependencyProperty IsIdleProperty = DependencyProperty.Register(nameof(IsIdle), typeof(bool), typeof(WinoCalendarFlipView), new PropertyMetadata(true));
+        public static readonly DependencyProperty ActiveCanvasProperty = DependencyProperty.Register(nameof(ActiveCanvas), typeof(WinoDayTimelineCanvas), typeof(WinoCalendarFlipView), new PropertyMetadata(null));
+
         public WinoDayTimelineCanvas ActiveCanvas
         {
             get { return (WinoDayTimelineCanvas)GetValue(ActiveCanvasProperty); }
             set { SetValue(ActiveCanvasProperty, value); }
         }
 
-        public static readonly DependencyProperty ActiveCanvasProperty = DependencyProperty.Register(nameof(ActiveCanvas), typeof(WinoDayTimelineCanvas), typeof(WinoCalendarFlipView), new PropertyMetadata(null));
+        public bool IsIdle
+        {
+            get { return (bool)GetValue(IsIdleProperty); }
+            set { SetValue(IsIdleProperty, value); }
+        }
 
         public WinoCalendarFlipView()
         {
             RegisterPropertyChangedCallback(SelectedIndexProperty, new DependencyPropertyChangedCallback(OnSelectedIndexUpdated));
+            RegisterPropertyChangedCallback(ItemsSourceProperty, new DependencyPropertyChangedCallback(OnItemsSourceChanged));
+        }
+
+        private static void OnItemsSourceChanged(DependencyObject d, DependencyProperty e)
+        {
+            if (d is WinoCalendarFlipView flipView)
+            {
+                flipView.RegisterItemsSourceChange();
+            }
         }
 
         private static void OnSelectedIndexUpdated(DependencyObject d, DependencyProperty e)
@@ -32,6 +49,19 @@ namespace Wino.Calendar.Controls
             }
         }
 
+        private void RegisterItemsSourceChange()
+        {
+            if (GetItemsSource() is INotifyCollectionChanged notifyCollectionChanged)
+            {
+                notifyCollectionChanged.CollectionChanged += ItemsSourceUpdated;
+            }
+        }
+
+        private void ItemsSourceUpdated(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            IsIdle = e.Action == NotifyCollectionChangedAction.Reset || e.Action == NotifyCollectionChangedAction.Replace;
+        }
+
         public async void UpdateActiveCanvas()
         {
             if (SelectedIndex < 0)

Wino.Calendar/Styles/WinoCalendarResources.xaml

@@ -139,16 +139,28 @@
             <Setter Property="Template">
                 <Setter.Value>
                     <ControlTemplate TargetType="controls:WinoCalendarControl">
+                        <Grid>
                             <controls:WinoCalendarFlipView
                                 x:Name="PART_WinoFlipView"
                                 HorizontalContentAlignment="Stretch"
                                 VerticalContentAlignment="Stretch"
                                 ActiveCanvas="{x:Bind ActiveCanvas, Mode=TwoWay}"
                                 Background="Transparent"
+                                IsIdle="{x:Bind IsFlipIdle, Mode=TwoWay}"
                                 IsTabStop="False"
                                 ItemTemplate="{StaticResource FlipTemplate}"
                                 ItemsSource="{TemplateBinding DayRanges}"
                                 SelectedIndex="{Binding SelectedFlipViewIndex, RelativeSource={RelativeSource Mode=TemplatedParent}, Mode=TwoWay}" />
+
+                            <Grid x:Name="PART_IdleGrid" Visibility="Collapsed">
+                                <muxc:ProgressRing
+                                    Width="50"
+                                    Height="50"
+                                    HorizontalAlignment="Center"
+                                    VerticalAlignment="Center"
+                                    IsActive="True" />
+                            </Grid>
+                        </Grid>
                     </ControlTemplate>
                 </Setter.Value>
             </Setter>