restoreScrollOffset method

  1. @protected
void restoreScrollOffset ()
@protected, inherited

Called whenever the ScrollPosition is created, to restore the scroll offset if possible.

The value is stored by saveScrollOffset when the scroll position changes, so that it can be restored in the case of the Scrollable being disposed then recreated in the same session. This might happen, for instance, if a ListView is on one of the pages inside a TabBarView, and that page is displayed, then hidden, then displayed again.

The default implementation reads the value from the nearest PageStorage found from the context's ScrollContext.storageContext property, and sets it using correctPixels, if pixels is still null.

This method is called from the constructor, so layout has not yet occurred, and the viewport dimensions aren't yet known when it is called.

Implementation

@protected
void restoreScrollOffset() {
  if (pixels == null) {
    final double value = PageStorage.of(context.storageContext)?.readState(context.storageContext) as double;
    if (value != null)
      correctPixels(value);
  }
}