Fix multiple timer initialized while changing slide

Author: neon-nyan

CollapseLauncher/XAMLs/Theme/CustomControls/PanelSlideshow.Events.cs

@@ -1,5 +1,4 @@
-#nullable enable
-using CommunityToolkit.WinUI;
+using CommunityToolkit.WinUI;
 using CommunityToolkit.WinUI.Animations;
 using Hi3Helper.Data;
 using Microsoft.UI.Input;
@@ -16,6 +15,7 @@
 using System.Numerics;
 using Windows.System;
 
+#nullable enable
 namespace CollapseLauncher.XAMLs.Theme.CustomControls;
 
 public partial class PanelSlideshow
@@ -59,6 +59,7 @@ private void ItemIndex_OnChange(int newIndex, int oldIndex)
 
         // Restart slideshow timer
         RestartTimer(SlideshowDuration);
+        ResetSlideshow();
 
         IList<UIElement> elements   = Items;
         UIElement        newElement = elements[newIndex];

CollapseLauncher/XAMLs/Theme/CustomControls/PanelSlideshow.Timer.cs

@@ -1,4 +1,5 @@
-using Microsoft.UI.Xaml;
+using CollapseLauncher.Extension;
+using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Media.Animation;
 using System;
 using System.Threading;
@@ -22,16 +23,28 @@ private async void RestartTimer(double newDurationSeconds, int delayBeforeStartM
     {
         try
         {
-            DisposeAndDeregisterTimer();
-            if (!IsLoaded || newDurationSeconds == 0)
+            if (!IsLoaded ||
+                !_isTemplateLoaded ||
+                newDurationSeconds == 0)
+            {
+                if (newDurationSeconds == 0)
+                {
+                    _countdownProgressBar.Value = 0;
+                }
+                DisposeAndDeregisterTimer();
+
+                return;
+            }
+
+            if (_timerStoryboard != null)
             {
                 return;
             }
 
             _countdownProgressBar.Minimum = 0;
             _countdownProgressBar.Maximum = 1;
 
-            _timerStoryboard = new Storyboard();
+            Interlocked.Exchange(ref _timerStoryboard, new Storyboard());
             DoubleAnimation animation = new()
             {
                 Duration                 = new Duration(TimeSpan.FromSeconds(newDurationSeconds)),
@@ -73,6 +86,7 @@ async void TimerStoryboardOnCompleted(object? sender, object e)
                 VisualStateManager.GoToState(this, StateNameCountdownProgressBarFadeOut, true);
                 await Task.Delay(500);
 
+                DisposeAndDeregisterTimer();
                 ItemIndex++;
             }
             catch (Exception ex)
@@ -82,16 +96,6 @@ async void TimerStoryboardOnCompleted(object? sender, object e)
         }
     }
 
-    private void DisposeAndDeregisterTimer()
-    {
-        if (!_isTemplateLoaded)
-        {
-            return;
-        }
-
-        Interlocked.Exchange(ref _timerStoryboard, null)?.Stop();
-    }
-
     /// <summary>
     /// Stops the slideshow countdown timer.
     /// </summary>
@@ -111,5 +115,20 @@ public void ResumeSlideshow()
         _timerStoryboard?.Resume();
     }
 
+    /// <summary>
+    /// Resets the slideshow countdown timer.
+    /// </summary>
+    public void ResetSlideshow()
+    {
+        _timerStoryboard?.Seek(TimeSpan.FromSeconds(0));
+    }
+
+    private void DisposeAndDeregisterTimer()
+    {
+        Storyboard? oldStoryboard = Interlocked.Exchange(ref _timerStoryboard, null);
+        oldStoryboard?.Stop();
+        oldStoryboard?.Children?.Clear();
+    }
+
     #endregion
 }