Pause/Resume gif on image visibility changed (#58)

* Pause/Resume gif on image visibility changed * Rollback formatting changes
XamlAnimatedGif · Feb 15, 2019 · ac96807 · ac96807
1 parent e07b77b
commit ac96807
Show file tree

Hide file tree

Showing 3 changed files with 39 additions and 4 deletions.
diff --git a/WpfAnimatedGif.Demo/MainWindow.xaml b/WpfAnimatedGif.Demo/MainWindow.xaml
@@ -64,6 +64,7 @@
                     <RadioButton Margin="5" Content="Specific count" IsChecked="{Binding UseSpecificRepeatCount}" />
                     <TextBox Margin="5" Text="{Binding RepeatCount}" Width="20" />
                     <CheckBox Margin="5" Content="Auto start" IsChecked="{Binding AutoStart}" />
+                    <CheckBox Margin="5" Content="Visibility" IsChecked="{Binding GifVisible}" />
                 </StackPanel>
 
                 <StackPanel Grid.Row="1" Grid.Column="2" HorizontalAlignment="Right" Orientation="Horizontal">

diff --git a/WpfAnimatedGif.Demo/MainWindow.xaml.cs b/WpfAnimatedGif.Demo/MainWindow.xaml.cs
@@ -188,7 +188,19 @@ public bool AutoStart
                 OnPropertyChanged("AutoStart");
             }
         }
-
+
+        private bool _gifVisible = true;
+        public bool GifVisible
+        {
+            get { return _gifVisible; }
+            set
+            {
+                _gifVisible = value;
+                img.Visibility = _gifVisible ? Visibility.Visible : Visibility.Collapsed;
+
+                OnPropertyChanged("GifVisible");
+            }
+        }
 
         public event PropertyChangedEventHandler PropertyChanged;
 

diff --git a/WpfAnimatedGif/ImageBehavior.cs b/WpfAnimatedGif/ImageBehavior.cs
@@ -290,6 +290,8 @@ private static void AnimatedSourceChanged(DependencyObject o, DependencyProperty
             {
                 imageControl.Loaded -= ImageControlLoaded;
                 imageControl.Unloaded -= ImageControlUnloaded;
+                imageControl.IsVisibleChanged -= VisibilityChanged;
+
                 AnimationCache.DecrementReferenceCount(oldValue, GetRepeatBehavior(imageControl));
                 var controller = GetAnimationController(imageControl);
                 if (controller != null)
@@ -300,11 +302,31 @@ private static void AnimatedSourceChanged(DependencyObject o, DependencyProperty
             {
                 imageControl.Loaded += ImageControlLoaded;
                 imageControl.Unloaded += ImageControlUnloaded;
+                imageControl.IsVisibleChanged += VisibilityChanged;
+
                 if (imageControl.IsLoaded)
                     InitAnimationOrImage(imageControl);
             }
         }
 
+        private static void VisibilityChanged(object sender, DependencyPropertyChangedEventArgs e)
+        {
+            if (sender is Image img && img.IsLoaded)
+            {
+                var controller = GetAnimationController(img);
+                if (controller != null)
+                {
+                    if ((bool)e.NewValue)
+                    {
+                        controller.GotoFrame(0);
+                        controller.Play();
+                    }
+                    else
+                        controller.Pause();
+                }
+            }
+        }
+
         private static void ImageControlLoaded(object sender, RoutedEventArgs e)
         {
             Image imageControl = sender as Image;
@@ -372,7 +394,7 @@ private static void InitAnimationOrImage(Image imageControl)
             bool isInDesignMode = DesignerProperties.GetIsInDesignMode(imageControl);
             bool animateInDesignMode = GetAnimateInDesignMode(imageControl);
             bool shouldAnimate = !isInDesignMode || animateInDesignMode;
-            
+
             // For a BitmapImage with a relative UriSource, the loading is deferred until
             // BaseUri is set. This method will be called again when BaseUri is set.
             bool isLoadingDeferred = IsLoadingDeferred(source, imageControl);
@@ -537,7 +559,7 @@ private static BitmapDecoder GetDecoder(BitmapSource image, Image imageControl,
             Stream stream = null;
             Uri uri = null;
             BitmapCreateOptions createOptions = BitmapCreateOptions.None;
-            
+
             var bmp = image as BitmapImage;
             if (bmp != null)
             {
@@ -625,7 +647,7 @@ private static GifFile DecodeGifFile(Uri uri)
                 if (uri.Authority == "siteoforigin:,,,")
                     sri = Application.GetRemoteStream(uri);
                 else
-                    sri = Application.GetResourceStream(uri); 
+                    sri = Application.GetResourceStream(uri);
 
                 if (sri != null)
                     stream = sri.Stream;