Method Push

io/input/pointer.go:730–784

(handlers map[event.Tag]*handler, state pointerState, e pointer.Event)

}

func (q *pointerQueue) Push(handlers map[event.Tag]*handler, state pointerState, e pointer.Event) (pointerState, []taggedEvent) {
	var evts []taggedEvent
	if e.Kind == pointer.Cancel {
		for k := range handlers {
			evts = append(evts, taggedEvent{
				event: pointer.Event{Kind: pointer.Cancel},
				tag:   k,
			})
		}
		state.pointers = nil
		return state, evts
	}
	if e.Kind == pointer.Scroll {
		// Scroll events are not bound to a pointer; see pointer.Event.PointerID.
		return state, q.deliverScrollEvent(handlers, evts, e)
	}
	state, pidx := state.pointerOf(e)
	p := state.pointers[pidx]

	switch e.Kind {
	case pointer.Press:
		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
		p.pressed = true
		evts = q.deliverEvent(handlers, p, evts, e)
	case pointer.Move:
		if p.pressed {
			e.Kind = pointer.Drag
		}
		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
		evts = q.deliverEvent(handlers, p, evts, e)
		if p.pressed {
			p, evts = q.deliverDragEvent(handlers, p, evts)
		}
	case pointer.Leave:
		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
	case pointer.Release:
		evts = q.deliverEvent(handlers, p, evts, e)
		p.pressed = false
		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
		p, evts = q.deliverDropEvent(handlers, p, evts)
	default:
		panic("unsupported pointer event type")
	}

	p.last = e

	if !p.pressed && len(p.entered) == 0 {
		// No longer need to track pointer.
		state.pointers = slices.Concat(state.pointers[:pidx:pidx], state.pointers[pidx+1:])
	} else {
		state.pointers = slices.Clone(state.pointers)
		state.pointers[pidx] = p
	}
	return state, evts
}

// deliverScrollEvent delivers scroll events to the handlers hit by the event coordinate.
func (q *pointerQueue) deliverScrollEvent(handlers map[event.Tag]*handler, evts []taggedEvent, e pointer.Event) []taggedEvent {