afterFirstLayout method
Implementation
void afterFirstLayout(BuildContext context) {
_handleScrollNotification(ScrollUpdateNotification(
metrics: FixedScrollMetrics(
minScrollExtent: controller.position.minScrollExtent,
maxScrollExtent: controller.position.maxScrollExtent,
pixels: controller.position.pixels,
devicePixelRatio: View.of(context).devicePixelRatio,
viewportDimension: controller.position.viewportDimension,
axisDirection: controller.position.axisDirection),
context: context,
scrollDelta: 0.0));
}