Fix calendarFormat bug, improve scrolling animation

lib/src/table_calendar_base.dart

@@ -108,8 +108,10 @@ class _TableCalendarBaseState extends State<TableCalendarBase>
     if (_focusedDay != widget.focusedDay ||
         widget.calendarFormat != oldWidget.calendarFormat ||
         widget.startingDayOfWeek != oldWidget.startingDayOfWeek) {
+      final shouldAnimate = _focusedDay != widget.focusedDay;
+
       _focusedDay = widget.focusedDay;
-      _updatePage();
+      _updatePage(shouldAnimate: shouldAnimate);
     }
 
     if (widget.rowHeight != oldWidget.rowHeight ||
@@ -136,7 +138,7 @@ class _TableCalendarBaseState extends State<TableCalendarBase>
       widget.availableGestures == AvailableGestures.all ||
       widget.availableGestures == AvailableGestures.verticalSwipe;
 
-  void _updatePage() {
+  void _updatePage({bool shouldAnimate = false}) {
     final currentIndex = _calculateFocusedPage(
         widget.calendarFormat, widget.firstDay, _focusedDay);
 
@@ -149,17 +151,27 @@ class _TableCalendarBaseState extends State<TableCalendarBase>
       _pageCallbackDisabled = true;
     }
 
-    _previousIndex = currentIndex;
-    final rowCount = _getRowCount(widget.calendarFormat, _focusedDay);
-    _pageHeight.value = _getPageHeight(rowCount);
+    if (shouldAnimate && widget.animatedPageScrolling) {
+      if ((currentIndex - _previousIndex).abs() > 1) {
+        final jumpIndex =
+            currentIndex > _previousIndex ? currentIndex - 1 : currentIndex + 1;
+
+        _pageController.jumpToPage(jumpIndex);
+      }
 
-    if (widget.animatedPageScrolling) {
-      _pageController.animateToPage(currentIndex,
-          duration: widget.pageChangeAnimationDuration,
-          curve: widget.pageChangeAnimationCurve);
+      _pageController.animateToPage(
+        currentIndex,
+        duration: widget.pageChangeAnimationDuration,
+        curve: widget.pageChangeAnimationCurve,
+      );
     } else {
       _pageController.jumpToPage(currentIndex);
     }
+
+    _previousIndex = currentIndex;
+    final rowCount = _getRowCount(widget.calendarFormat, _focusedDay);
+    _pageHeight.value = _getPageHeight(rowCount);
+
     _pageCallbackDisabled = false;
   }