function moveShape(shape) {
    if (!movingShapes.includes(shape)) {
      movingShapes.push(shape);
    }

    var label = shape.label;

    // move external label if its label target is moving
    if (label && !movingShapes.includes(label)) {
      movingShapes.push(label);
    }
  }
Get elements to be moved and resized.

@param {Array<Shape>} elements
@param {Axis} axis
@param {Point} delta
@param {number} start

@return {Object}