Method _getDragDistance

src/cdk/drag-drop/drag-ref.ts:1426–1434

* Gets the distance that the user has dragged during the current drag sequence. * @param currentPosition Current position of the user's pointer.

(currentPosition: Point)

   * @param currentPosition Current position of the user's pointer.
   */
  private _getDragDistance(currentPosition: Point): Point {
    const pickupPosition = this._pickupPositionOnPage;

    if (pickupPosition) {
      return {x: currentPosition.x - pickupPosition.x, y: currentPosition.y - pickupPosition.y};
    }

    return {x: 0, y: 0};
  }

  /** Cleans up any cached element dimensions that we don't need after dragging has stopped. */
  private _cleanupCachedDimensions() {