Merge "[multi-shade] Fix multi touch bug." into udc-dev

                interactionState = null

                true

            }

            MotionEvent.ACTION_POINTER_UP -> {

                val removedPointerId = event.getPointerId(event.actionIndex)

                if (removedPointerId == interactionState?.pointerId && event.pointerCount > 1) {

                    // We removed the original pointer but there must be another pointer because the

                    // gesture is still ongoing. Let's switch to that pointer.

                    interactionState =

                        event.firstUnremovedPointerId(removedPointerId)?.let { replacementPointerId

                            ->

                            interactionState?.copy(

                                pointerId = replacementPointerId,

                                // We want to update the currentY of our state so that the

                                // transition to the next pointer doesn't report a big jump between

                                // the Y coordinate of the removed pointer and the Y coordinate of

                                // the replacement pointer.

                                currentY = event.getY(replacementPointerId),

                            )

                        }

                }

                true

            }

            MotionEvent.ACTION_CANCEL -> {

                if (isDraggingShade()) {

                    // Our drag gesture was canceled by the system. This happens primarily in one of

    private fun isDraggingShade(): Boolean {

        return interactionState?.isDraggingShade ?: false

    }

    /**

     * Returns the index of the first pointer that is not [removedPointerId] or `null`, if there is

     * no other pointer.

     */

    private fun MotionEvent.firstUnremovedPointerId(removedPointerId: Int): Int? {

        return (0 until pointerCount)

            .firstOrNull { pointerIndex ->

                val pointerId = getPointerId(pointerIndex)

                pointerId != removedPointerId

            }

            ?.let { pointerIndex -> getPointerId(pointerIndex) }

    }

}