Adjusted event bindings flow in Marquee control

Author: Avid29

components/Marquee/src/Marquee.Events.cs

@@ -12,9 +12,6 @@ public partial class Marquee
     /// <summary>
     /// Event raised when the Marquee begins scrolling.
     /// </summary>
-    /// <remarks>
-    /// Could be started. Could be resumed.
-    /// </remarks>
     public event EventHandler? MarqueeStarted;
 
     /// <summary>
@@ -41,14 +38,19 @@ private void Marquee_Loaded(object sender, RoutedEventArgs e)
     {
         // While loaded, detach the loaded event and attach the unloaded event
         this.Loaded -= this.Marquee_Loaded;
-        this.Unloaded += Marquee_Unloaded;
+        this.Unloaded += this.Marquee_Unloaded;
 
         // Attach other events
         if (_marqueeContainer is not null)
         {
             _marqueeContainer.SizeChanged += Container_SizeChanged;
         }
 
+        if (_segment1 is not null)
+        {
+            _segment1.SizeChanged += Segment_SizeChanged;
+        }
+
         if (_marqueeStoryboard is not null)
         {
             _marqueeStoryboard.Completed += StoryBoard_Completed;
@@ -66,6 +68,11 @@ private void Marquee_Unloaded(object sender, RoutedEventArgs e)
             _marqueeContainer.SizeChanged -= Container_SizeChanged;
         }
 
+        if (_segment1 is not null)
+        {
+            _segment1.SizeChanged -= Segment_SizeChanged;
+        }
+
         if (_marqueeStoryboard is not null)
         {
             _marqueeStoryboard.Completed -= StoryBoard_Completed;
@@ -75,9 +82,7 @@ private void Marquee_Unloaded(object sender, RoutedEventArgs e)
     private void Container_SizeChanged(object sender, SizeChangedEventArgs e)
     {
         if (_marqueeContainer is null)
-        {
             return;
-        }
 
         // Clip the marquee within its bounds
         _marqueeContainer.Clip = new RectangleGeometry
@@ -99,9 +104,7 @@ private void Container_SizeChanged(object sender, SizeChangedEventArgs e)
     private void Segment_SizeChanged(object sender, SizeChangedEventArgs e)
     {
         if (_segment1 is null)
-        {
             return;
-        }
 
         // If the segment size changes, we need to update the storyboard,
         // and seek to the correct position to maintain a smooth animation.

components/Marquee/src/Marquee.cs

@@ -61,6 +61,14 @@ public Marquee()
         DefaultStyleKey = typeof(Marquee);
     }
 
+    /// <summary>
+    /// Unsubscribes from the loaded event when the control is being disposed.
+    /// </summary>
+    ~Marquee()
+    {
+        Loaded -= this.Marquee_Loaded;
+    }
+
     /// <inheritdoc/>
     protected override void OnApplyTemplate()
     {
@@ -72,12 +80,10 @@ protected override void OnApplyTemplate()
         _segment2 = (ContentPresenter)GetTemplateChild(Segment2PartName);
         _marqueeTransform = (TranslateTransform)GetTemplateChild(MarqueeTransformPartName);
 
-        _marqueeContainer.SizeChanged += Container_SizeChanged;
-        _segment1.SizeChanged += Segment_SizeChanged;
-
         // Swapping tabs in TabView caused errors where the control would unload and never reattach events.
-        // Hotfix: Track the loaded event. This should be fine because the GC will handle detaching the Loaded
-        // event on disposal. However, more research is required
+        // Fix: Track the loaded event. This should be fine because the GC will handle detaching the Loaded
+        // event on disposal. However, more research is required.
+        // As a result, all other events should be attached in the Loaded event handler.
         Loaded += this.Marquee_Loaded;
 
         VisualStateManager.GoToState(this, GetVisualStateName(Direction), false);
@@ -192,7 +198,7 @@ private void PlayMarquee(bool fromStart = false)
         }
 
         // Do nothing if storyboard is null or already playing and not from start.
-        if (_marqueeStoryboard is null || _isActive && !fromStart)
+        if (_marqueeStoryboard is null || (_isActive && !fromStart))
             return;
 
         bool wasActive = _isActive;
@@ -269,6 +275,12 @@ private bool UpdateAnimation(out TimeSpan seekPoint)
         if (!HasTemplateParts())
             return false;
 
+        // Unbind events from the old storyboard
+        if (_marqueeStoryboard is not null)
+        {
+            _marqueeStoryboard.Completed -= StoryBoard_Completed;
+        }
+
         // Get the size of the container and segment, based on the orientation.
         // Also track the property to adjust, also based on the orientation.
         double containerSize;
@@ -326,6 +338,7 @@ private bool UpdateAnimation(out TimeSpan seekPoint)
         // If the distance is zero, don't play an animation
         if (distance is 0)
         {
+            _marqueeStoryboard = null;
             return false;
         }
 
@@ -341,12 +354,6 @@ private bool UpdateAnimation(out TimeSpan seekPoint)
         // Calculate the animation duration by dividing the distance by the speed
         TimeSpan duration = TimeSpan.FromSeconds(distance / Speed);
 
-        // Unbind events from the old storyboard
-        if (_marqueeStoryboard is not null)
-        {
-            _marqueeStoryboard.Completed -= StoryBoard_Completed;
-        }
-
         // Create new storyboard and animation
         _marqueeStoryboard = CreateMarqueeStoryboardAnimation(start, end, duration, targetProperty);