Slider<D> constructor

Slider<D>({ SelectionTrigger eventTrigger = SelectionTrigger.tapAndDrag, SymbolRenderer? handleRenderer, D? initialDomainValue, SliderListenerCallback<D>? onChangeCallback, String? roleId, bool snapToDatum = false, SliderStyle? style, int layoutPaintOrder = LayoutViewPaintOrder.slider, })

Constructs a Slider.

eventTrigger sets the type of gesture handled by the slider.

handleRenderer draws a handle for the slider. Defaults to a rectangle.

initialDomainValue sets the initial position of the slider in domain units. The default is the center of the chart.

onChangeCallback will be called when the position of the slider changes during a drag event.

roleId optional custom role ID for the slider. This can be used to allow multiple Slider behaviors on the same chart. Normally, there can only be one slider (per event trigger type) on a chart. This setting allows for configuring multiple independent sliders.

snapToDatum configures the slider to snap snap onto the nearest datum (by domain distance) when dragged. By default, the slider can be positioned anywhere along the domain axis.

style configures the color and sizing of the slider line and handle.

layoutPaintOrder configures the order in which the behavior should be painted. This value should be relative to LayoutPaintViewOrder.slider. (e.g. LayoutViewPaintOrder.slider + 1).

Implementation

Slider(
    {this.eventTrigger = SelectionTrigger.tapAndDrag,
    SymbolRenderer? handleRenderer,
    D? initialDomainValue,
    SliderListenerCallback<D>? onChangeCallback,
    String? roleId,
    this.snapToDatum = false,
    SliderStyle? style,
    this.layoutPaintOrder = LayoutViewPaintOrder.slider})
    : _handleRenderer = handleRenderer ?? RectSymbolRenderer(),
      _roleId = roleId ?? '',
      _style = style ?? SliderStyle(),
      _domainValue = initialDomainValue {
  if (_domainValue != null) {
    _dragStateToFireOnPostRender = SliderListenerDragState.initial;
  }

  // Setup the appropriate gesture listening.
  switch (eventTrigger) {
    case SelectionTrigger.tapAndDrag:
      _gestureListener = GestureListener(
          onTapTest: _onTapTest,
          onTap: _onSelect,
          onDragStart: _onSelect,
          onDragUpdate: _onSelect,
          onDragEnd: _onDragEnd);
      break;
    case SelectionTrigger.pressHold:
      _gestureListener = GestureListener(
          onTapTest: _onTapTest,
          onLongPress: _onSelect,
          onDragStart: _onSelect,
          onDragUpdate: _onSelect,
          onDragEnd: _onDragEnd);
      break;
    case SelectionTrigger.longPressHold:
      _gestureListener = GestureListener(
          onTapTest: _onTapTest,
          onLongPress: _onLongPressSelect,
          onDragStart: _onSelect,
          onDragUpdate: _onSelect,
          onDragEnd: _onDragEnd);
      break;
    default:
      throw ArgumentError('Slider does not support the event trigger '
          '"$eventTrigger"');
  }

  // Set up chart draw cycle listeners.
  _lifecycleListener = LifecycleListener<D>(
    onData: _setInitialDragState,
    onAxisConfigured: _updateViewData,
    onPostrender: _fireChangeEvent,
  );

  // Set up slider event listeners.
  _sliderEventListener = SliderEventListener<D>(onChange: onChangeCallback);
}