Pointer, Mouse, Touch, and Pen

Pointer (from scenerystack/scenery) is scenery's abstraction for a single input device: the one system mouse, one instance per active touch contact, or one instance per stylus. Every scenery input event carries a reference to the Pointer that triggered it via SceneryEvent.pointer, and listeners like FireListener and DragListener track pointers internally to know when a press is still "over" their target. Pointer itself is abstract — what you actually get is always a Mouse, Touch, or Pen instance (or the internal PDOM pointer used for keyboard/assistive-technology activation).

import { FireListener, Mouse } from 'scenerystack/scenery';

button.addInputListener( new FireListener( {
  press: ( event, listener ) => {
    // Special-case mouse-only behavior, e.g. restrict to the right button
    if ( event.pointer instanceof Mouse ) {
      console.log( 'pressed with the mouse' );
    }
  }
} ) );

The Pointer base class

Member	Meaning
point	Current position in the global (Display root) coordinate frame
type	'mouse' | 'touch' | 'pen' | 'pdom' — cheaper than an instanceof check when you just need the category
trail	The Trail this pointer is currently over, updated as it moves
isDownProperty	Whether the pointer is currently pressed
attachedProperty / isAttached()	Whether a "primary" listener has claimed this pointer (see attach on PressListener) — used to prevent two listeners from responding to the same physical drag
cursor	An override cursor that takes precedence over the trail's CSS cursor, typically set for the duration of a drag
isTouchLike()	true for Touch and Pen, false for Mouse — useful when code should treat touch and pen the same way
addInputListener( listener, attach? ) / removeInputListener( listener )	Attaches a listener directly to the pointer (rather than to a Node) — this is how PressListener tracks moves/releases after a press starts
interruptAttached()	Interrupts whichever listener is currently attached, if any
interruptAll()	Interrupts every listener on this pointer
reserveForDrag() / reserveForKeyboardDrag()	Marks the pointer with an Intent (Intent.DRAG or Intent.KEYBOARD_DRAG) so other listeners in the same dispatch can change behavior — DragListener calls reserveForDrag() automatically on a successful press
hasIntent( intent )	Checks whether a given Intent is currently set

Mouse, Touch, and Pen

Class	type	Notes
Mouse	'mouse'	A singleton per Display — there's only ever one. Adds leftDown/middleDown/rightDown (deprecated in favor of DOM button tracking), plus wheelDelta/wheelDeltaMode for wheel events
Touch	'touch'	One instance per active touch contact, identified by id. isTouchLike() returns true
Pen	'pen'	One instance per active stylus contact, identified by id. Also carries tilt/pressure information from the underlying PointerEvent. isTouchLike() returns true

Because touches come and go as fingers land and lift, code that needs to distinguish "the mouse" from "some touch" should check pointer.type === 'mouse' or pointer instanceof Mouse, not assume there's exactly one pointer active at a time — a multi-touch interaction can have several Touch pointers live simultaneously.

Prefer mouseButton and pressCursor over checking Mouse yourself

Most pointer-type-specific behavior is already exposed as options on the listeners themselves — PressListener's mouseButton restricts which mouse button starts a press (any touch/pen still works), and pressCursor only visibly applies to Mouse anyway (touch/pen have no persistent cursor). Reach for instanceof Mouse only when you need behavior no listener option already covers.