Gallery updates

src/PicView.Avalonia/CustomControls/GalleryListBox.cs

@@ -161,6 +161,12 @@ public void ScrollToEnd()
         _autoScrollViewer.Offset = new Vector(double.PositiveInfinity, double.PositiveInfinity);
         _autoScrollViewer.ScrollToEnd();
     }
+
+    public void ScrollToHome()
+    {
+        _autoScrollViewer.Offset = new Vector(double.NegativeInfinity, double.NegativeInfinity);
+        _autoScrollViewer.ScrollToHome();
+    }
 
     public void PageLeft()
     {

src/PicView.Avalonia/CustomControls/ThumbImage.cs

@@ -0,0 +1,51 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Media;
+
+namespace PicView.Avalonia.CustomControls;
+
+public class ThumbImage : Image
+{
+    protected override Size MeasureOverride(Size availableSize)
+    {
+        Size? size = null;
+        try
+        {
+            size = new Size();
+
+
+        if (Source != null)
+        {
+            size = Stretch.CalculateSize(availableSize, Source.Size, StretchDirection);
+        }
+        }
+        catch (Exception e)
+        {
+#if DEBUG
+            Console.WriteLine(e);
+#endif
+        }
+
+        return size ?? new Size();
+    }
+
+    protected override Size ArrangeOverride(Size finalSize)
+    {
+        try
+        {
+            if (Source != null)
+            {
+                var sourceSize = Source.Size;
+                var result = Stretch.CalculateSize(finalSize, sourceSize);
+                return result;
+            }
+        }
+        catch (Exception e)
+        {
+#if DEBUG
+            Console.WriteLine(e);
+#endif
+        }
+        return new Size();
+    }
+}