enhance: only raise BlockNavigationChangedEvent when UseBlockNavigation enabled

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Views/DiffView.axaml.cs

@@ -37,7 +37,7 @@ private void OnGotoLastChange(object _, RoutedEventArgs e)
 
         private void OnBlockNavigationChanged(object sender, RoutedEventArgs e)
         {
-            if (sender is TextDiffView { UseBlockNavigation: true } textDiff)
+            if (sender is TextDiffView textDiff)
                 BlockNavigationIndicator.Text = textDiff.BlockNavigation?.Indicator ?? string.Empty;
         }
     }

src/Views/TextDiffView.axaml.cs

@@ -1746,25 +1746,25 @@ public TextDiffView()
         public void GotoFirstChange()
         {
             this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoFirstChange();
-            RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+            TryRaiseBlockNavigationChanged();
         }
 
         public void GotoPrevChange()
         {
             this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoPrevChange();
-            RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+            TryRaiseBlockNavigationChanged();
         }
 
         public void GotoNextChange()
         {
             this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoNextChange();
-            RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+            TryRaiseBlockNavigationChanged();
         }
 
         public void GotoLastChange()
         {
             this.FindDescendantOfType<ThemedTextDiffPresenter>()?.GotoLastChange();
-            RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+            TryRaiseBlockNavigationChanged();
         }
 
         protected override void OnDataContextChanged(EventArgs e)
@@ -1818,7 +1818,7 @@ private void RefreshBlockNavigation()
             else
                 BlockNavigation = null;
 
-            RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+            TryRaiseBlockNavigationChanged();
         }
 
         private void OnStageChunk(object _1, RoutedEventArgs _2)
@@ -1990,5 +1990,11 @@ private void OnDiscardChunk(object _1, RoutedEventArgs _2)
             repo.MarkWorkingCopyDirtyManually();
             repo.SetWatcherEnabled(true);
         }
+
+        private void TryRaiseBlockNavigationChanged()
+        {
+            if (UseBlockNavigation)
+                RaiseEvent(new RoutedEventArgs(BlockNavigationChangedEvent));
+        }
     }
 }