showModalSlidingPanel<T> function Null safety

Future<T?> showModalSlidingPanel<T>(
  1. {required BuildContext context,
  2. required SlidingPanel panel(
    1. BuildContext

Shows a modal SlidingPanel.

Works similar to showModalBottomSheet. The normal SlidingPanel is just a widget. But by calling this, the panel acts as a whole new route.

You can customize the panel as usual. (See below for changes).

Returns a Future that resolves to the value (if any) that was passed to Navigator.pop when the SlidingPanel was closed.

Below things affect the panel behavior, rest is not affected:

SlidingPanel.parallaxSlideAmount will not work. SlidingPanel.animatedAppearing is ignored, as the modal panel always animtes while it appears. PanelContent.bodyContent is ignored.

When initialized (this function is called), a new route will be pushed. After pushing the route, the initial state (animation) of the panel is decided by SlidingPanel.initialState as below:

(1) For two-state panels, InitialPanelState.collapsed is ALWAYS considered to be InitialPanelState.expanded.

(2) If InitialPanelState.closed is given, and IF PanelSize.closedHeight is 0.0, it will be considered as InitialPanelState.collapsed (and InitialPanelState.expanded for two-state).

(3) If InitialPanelState.dismissed is given, it will be considered as InitialPanelState.closed. (Will also change the decision based on above given conditions).

After this, panel will listen for changes in its position. Route's popping is decided by BackPressBehavior and PanelPoppingBehavior.

A panel is also considered to pop the route, when:

(1) When PanelSize.closedHeight is 0.0 and PanelState.closed happens, either by dragging or by PanelController, the route gets popped.

(2) When PanelSize.closedHeight is more than 0.0 (e.g., PanelAutoSizing.headerSizeIsClosed used), PanelState.closed won't pop the route. At that time, currentHeight=0.0 (PanelState.dismissed) pops the route.


Future<T?> showModalSlidingPanel<T>(
    {required BuildContext context,
    required SlidingPanel Function(BuildContext) panel}) {
  if (panel != null) {
    SlidingPanel _panel = panel(context);

    return Navigator.of(context).push(
        duration: _panel.duration,
        panelRouteBuilder: (route) {
          return SlidingPanel._modal(
            key: _panel.key,
            initialState: _panel.initialState,
            content: PanelContent(
                panelContent: _panel.content.panelContent,
                collapsedWidget: _panel.content.collapsedWidget,
                headerWidget: _panel.content.headerWidget,
                footerWidget: _panel.content.footerWidget,
                bodyContent: null),
            size: _panel.size,
            maxWidth: _panel.maxWidth,
            decoration: _panel.decoration,
            backdropConfig: _panel.backdropConfig,
            panelController: _panel.panelController,
            autoSizing: _panel.autoSizing,
            renderPanelBackground: _panel.renderPanelBackground,
            snapping: _panel.snapping,
            snappingTriggerPercentage: _panel.snappingTriggerPercentage,
            isDraggable: _panel.isDraggable,
            physics: _panel.physics,
            dragMultiplier: _panel.dragMultiplier,
            duration: _panel.duration,
            curve: _panel.curve,
            isTwoStatePanel: _panel.isTwoStatePanel,
            backPressBehavior: _panel.backPressBehavior,
            panelPoppingBehavior: _panel.panelPoppingBehavior,
            panelClosedOptions: _panel.panelClosedOptions,
            safeAreaConfig: _panel.safeAreaConfig,
            onPanelSlide: _panel.onPanelSlide,
            onPanelStateChanged: _panel.onPanelStateChanged,
            onThrowResult: _panel.onThrowResult,
  return Future.value(null);