anchor.diff:    FixedExtentDelegate verticalExtentDelegate;
   
     LinkedScrollControllerGroup horizontalController;
  -
  -  double get maxScrollOffset =>
  -      widget.containerWidth * (zoomController.value - 1);
   
     /// Animation controller for animating flame chart zoom changes.
     AnimationController zoomController;
  
positive.code:   Future<void> scrollVerticallyToData(V data) async {
      await verticalController.animateTo(
        // Subtract [2 * rowHeightWithPadding] to give the target scroll event top padding.
        (topYForData(data) - 2 * rowHeightWithPadding)
            .clamp(0.0, verticalController.position.maxScrollExtent),
        duration: shortDuration,
        curve: defaultCurve,
      );
  
negative.code:             FlameChart.maxZoomLevel,
            );
            await zoomTo(newZoomLevel, jump: true);
            if (newZoomLevel == FlameChart.minZoomLevel &&
                horizontalController.offset != 0.0) {
              await scrollToX(0.0);
            }
          }
        }
      }
  