calcPersistentHeaderExtent static method
double
calcPersistentHeaderExtent({
- GlobalKey<
State< ? key,StatefulWidget> > - BuildContext? context,
- required double offset,
Calculate current extent of RenderSliverPersistentHeader base on target layout offset. Such as SliverAppBar
You must pass either key
or context
Implementation
static double calcPersistentHeaderExtent({
GlobalKey? key,
BuildContext? context,
required double offset,
}) {
assert(key != null || context != null);
final ctx = key?.currentContext ?? context;
final obj = ObserverUtils.findRenderObject(ctx);
if (obj is! RenderSliverPersistentHeader) return 0;
final maxExtent = obj.maxExtent;
final minExtent = obj.minExtent;
final currentExtent = math.max(minExtent, maxExtent - offset);
return currentExtent;
}