showOverlay function

OverlaySupportEntry showOverlay(AnimatedOverlayWidgetBuilder builder, { Curve? curve, Duration? duration, Key? key, BuildContext? context, Duration? animationDuration, Duration? reverseAnimationDuration, })

Basic api to show overlay widget.

duration : the overlay display duration , overlay will auto dismiss after duration. if null , will be set to kNotificationDuration. if zero , will not auto dismiss in the future.

builder : see AnimatedOverlayWidgetBuilder.

curve : adjust the rate of change of an animation.

key : to identify a OverlayEntry.

for example:

final key = ValueKey('my overlay');

// step 1: popup a overlay
showOverlay(builder, key: key);

// step 2: popup a overlay use the same key
showOverlay(builder2, key: key);

If the notification1 of step1 is showing, the step2 will dismiss previous notification1.

If you want notification1' exist to prevent step2, please see ModalKey

Implementation

OverlaySupportEntry showOverlay(
  AnimatedOverlayWidgetBuilder builder, {
  Curve? curve,
  Duration? duration,
  Key? key,
  BuildContext? context,
  Duration? animationDuration,
  Duration? reverseAnimationDuration,
}) {
  assert(key is! GlobalKey);

  final overlaySupport = findOverlayState(context: context);
  final overlay = overlaySupport?.overlayState;
  if (overlaySupport == null || overlay == null) {
    assert(() {
      debugPrint('overlay not available, dispose this call : $key');
      return true;
    }());
    return OverlaySupportEntry.empty();
  }

  final overlayKey = key ?? UniqueKey();

  final oldSupportEntry = overlaySupport.getEntry(key: overlayKey);
  if (oldSupportEntry != null && key is ModalKey) {
    // Do nothing for modal key if there be a OverlayEntry hold the same model key
    // and it is showing.
    return oldSupportEntry;
  }

  final dismissImmediately = key is TransientKey;
  // If we got a showing overlaySupport with [key], we should dismiss it before showing a new.
  oldSupportEntry?.dismiss(animate: !dismissImmediately);

  final stateKey = GlobalKey<_AnimatedOverlayState>();
  final entry = OverlayEntry(builder: (context) {
    return KeyedOverlay(
      key: overlayKey,
      child: _AnimatedOverlay(
        key: stateKey,
        builder: builder,
        curve: curve,
        animationDuration: animationDuration ?? kNotificationSlideDuration,
        reverseAnimationDuration:
            reverseAnimationDuration ?? kNotificationSlideDuration,
        duration: duration ?? kNotificationDuration,
        overlayKey: overlayKey,
        overlaySupportState: overlaySupport,
      ),
    );
  });
  final supportEntry = OverlaySupportEntry._internal(
      entry, overlayKey, stateKey, overlaySupport);
  overlaySupport.addEntry(supportEntry, key: overlayKey);
  overlay.insert(entry);
  return supportEntry;
}