of static method

ScrollableState of(
  1. BuildContext context, {
  2. Axis? axis,
})

The state from the closest instance of this class that encloses the given context.

Typical usage is as follows:

ScrollableState scrollable = Scrollable.of(context);

Calling this method will create a dependency on the ScrollableState that is returned, if there is one. This is typically the closest Scrollable, but may be a more distant ancestor if axis is used to target a specific Scrollable.

Using the optional Axis is useful when Scrollables are nested and the target Scrollable is not the closest instance. When axis is provided, the nearest enclosing ScrollableState in that Axis is returned.

This finds the nearest ancestor Scrollable of the context. This means that if the context is that of a Scrollable, it will not find that Scrollable.

If no Scrollable ancestor is found, then this method will assert in debug mode, and throw an exception in release mode.

See also:

Implementation

static ScrollableState of(BuildContext context, { Axis? axis }) {
  final ScrollableState? scrollableState = maybeOf(context, axis: axis);
  assert(() {
    if (scrollableState == null) {
      throw FlutterError.fromParts(<DiagnosticsNode>[
        ErrorSummary(
          'Scrollable.of() was called with a context that does not contain a '
          'Scrollable widget.',
        ),
        ErrorDescription(
          'No Scrollable widget ancestor could be found '
          '${axis == null ? '' : 'for the provided Axis: $axis '}'
          'starting from the context that was passed to Scrollable.of(). This '
          'can happen because you are using a widget that looks for a Scrollable '
          'ancestor, but no such ancestor exists.\n'
          'The context used was:\n'
          '  $context',
        ),
        if (axis != null) ErrorHint(
          'When specifying an axis, this method will only look for a Scrollable '
          'that matches the given Axis.',
        ),
      ]);
    }
    return true;
  }());
  return scrollableState!;
}