add animated_swither

lib/src/ui/page/photo_main_page.dart

@@ -99,6 +99,7 @@ class _PhotoMainPageState extends State<PhotoMainPage>
   void _closeGallerySelectDialog() {
     overlayEntry.remove();
     overlayEntry = null;
+    setState(() {});
   }
 
   void _showGallerySelectDialog() {
@@ -147,6 +148,7 @@ class _PhotoMainPageState extends State<PhotoMainPage>
       );
     });
     Overlay.of(context).insert(overlayEntry);
+    setState(() {});
   }
 
   @override
@@ -170,10 +172,37 @@ class _PhotoMainPageState extends State<PhotoMainPage>
               alignment: Alignment.center,
               height: 44.0,
               padding: EdgeInsets.zero.copyWith(right: kToolbarHeight),
-              child: Text(currentGalleryName, style: options.theme.textStyle.apply(
-                fontSizeDelta: 2.0,
-                fontWeightDelta: 1,
-              ),),
+              child: Row(
+                mainAxisAlignment: MainAxisAlignment.center,
+                children: [
+                  Text(currentGalleryName, style: options.theme.textStyle.apply(
+                    fontSizeDelta: 2.0,
+                    fontWeightDelta: 1,
+                  ),),
+                  Container(
+                    width: 18,
+                    height: 18,
+                    margin: EdgeInsets.only(left: 8),
+                    decoration: ShapeDecoration(shape: CircleBorder(
+                      side: BorderSide(
+                        color: options.theme.onSurfaceColor,
+                        width: 1.5
+                      ),
+                    )),
+                    child: AnimatedSwitcher(
+                      transitionBuilder: (child, animation){
+                        final Tween<double> tween = overlayEntry != null ? Tween(begin: -0.25, end: 0.25) : Tween(begin: 0.25, end: 0.75);
+                        //var tween = Tween(begin: -0.5, end: 0.0);
+                        return RotationTransition(child: child, turns: tween.animate(animation));
+                      },
+                      duration: Duration(milliseconds: 200),
+                      reverseDuration: Duration(milliseconds: 0),
+                      child: Icon(Icons.chevron_left, key: ValueKey(overlayEntry == null ? 0 : 1),  size: 14, color: options.theme.onSurfaceColor),
+                    ),
+                  ),
+                ],
+              )
+              
             ),
           ),
         ),