onScroll method

bool onScroll(
  1. ScrollNotification notification
)

Implementation

bool onScroll (ScrollNotification notification)
{
  if ((notification.metrics.axisDirection == AxisDirection.left) || (notification.metrics.axisDirection == AxisDirection.right)) return false;

  double maxHeight = widget.model.header?.height ?? widget.model.header?.constraints.maxHeight ?? 0;
  if (maxHeight.isNegative) maxHeight = 0;

  double minHeight = widget.model.header?.height ?? widget.model.header?.constraints.minHeight ?? 0;
  if (minHeight.isNegative) minHeight = 0;

  // Non-Resizeable Header
  if (minHeight == maxHeight) return true;
  double height;
  double scrolled = notification.metrics.pixels;
  scrolled = scrolled > maxHeight ? maxHeight : scrolled;

  height = maxHeight - scrolled;
  if (height < minHeight) height = minHeight;

  var viewportHeight = widget.model.system.maxHeight!;
  widget.model.header?.height = height;
  widget.model.height = viewportHeight - height - (widget.model.footer?.constraints.height ?? 0) - safeAreaHeight.ceil();

  /* Stop Notification Bubble */
  return false;
}