builder method

List<Widget> builder(BuildContext context, BoxConstraints constraints)

Implementation

List<Widget> builder(BuildContext context, BoxConstraints constraints) {

  // Check if widget is visible before wasting resources on building it
  if (!widget.model.visible) return const [Offstage()];

  /// Busy / Loading Indicator
  busy ??= BusyModel(widget.model,
          visible: widget.model.busy, observable: widget.model.busyObservable)
      .getView();

  // Direction
  var direction = widget.model.directionOf();

  List<Widget> children = [];

  // View
  Widget view;
  switch (widget.model.collapsed) {
    // collapsed list
    case true:
      view = SingleChildScrollView(
          physics: widget.model.onpulldown != null
              ? const AlwaysScrollableScrollPhysics()
              : null,
          child: ExpansionPanelList.radio(
              dividerColor: Theme.of(context).colorScheme.onInverseSurface,
              initialOpenPanelValue: 0,
              elevation: 2,
              expandedHeaderPadding: const EdgeInsets.all(4),
              children: expansionItems(context)));
      break;

    // regular list
    case false:

      int? items = widget.model.datasource == null ? widget.model.items.length : widget.model.data?.length;

      view = ListView.builder(
          reverse: widget.model.reverse,
          itemCount: items,
          physics: widget.model.onpulldown != null
              ? const AlwaysScrollableScrollPhysics()
              : null,
          scrollDirection: direction,
          controller: controller,
          itemBuilder: itemBuilder);

      break;
  }

  if (widget.model.onpulldown != null) {
    view = RefreshIndicator(
        onRefresh: () => widget.model.onPull(context), child: view);
  }

  if (widget.model.onpulldown != null || widget.model.allowDrag) {
    view = ScrollConfiguration(
      behavior: ScrollConfiguration.of(context).copyWith(
        dragDevices: {
          PointerDeviceKind.touch,
          PointerDeviceKind.mouse,
        },
      ),
      child: view,
    );
  }

  // add list
  children.add(view);

  // add busy
  children.add(Center(child: busy));

  // show busy spinner over list
  view = Stack(children: children);

  return [view];
}