buildSimpleRefreshIndicator method

Widget buildSimpleRefreshIndicator (BuildContext context, RefreshIndicatorMode refreshState, double pulledExtent, double refreshTriggerPullDistance, double refreshIndicatorExtent)

Builds a simple refresh indicator that fades in a bottom aligned down arrow before the refresh is triggered, a CupertinoActivityIndicator during the refresh and fades the CupertinoActivityIndicator away when the refresh is done.

Implementation 

static Widget buildSimpleRefreshIndicator(BuildContext context,
  RefreshIndicatorMode refreshState,
  double pulledExtent,
  double refreshTriggerPullDistance,
  double refreshIndicatorExtent,
) {
  const Curve opacityCurve = Interval(0.4, 0.8, curve: Curves.easeInOut);
  return Align(
    alignment: Alignment.bottomCenter,
    child: Padding(
      padding: const EdgeInsets.only(bottom: 16.0),
      child: refreshState == RefreshIndicatorMode.drag
          ? Opacity(
              opacity: opacityCurve.transform(
                min(pulledExtent / refreshTriggerPullDistance, 1.0)
              ),
              child: const Icon(
                CupertinoIcons.down_arrow,
                color: CupertinoColors.inactiveGray,
                size: 36.0,
              ),
            )
          : Opacity(
              opacity: opacityCurve.transform(
                min(pulledExtent / refreshIndicatorExtent, 1.0)
              ),
              child: const CupertinoActivityIndicator(radius: 14.0),
            ),
    ),
  );
}