/**
 * An axis coupling mode is a mode that is applied to a {@link ViewportWidget}
 * on a per-axis basis. The mode controls how a ViewportWidget's axis length
 * relates to a ViewportWidget child's axis length.
 *
 * If two axes are not coupled, then they do not affect each other's length in
 * any way. If two axes are bi-directionally coupled, then they will always have
 * the same length. If two axes are uni-directionally coupled, then one axis
 * will affect the length of another axis, but not the other way around.
 *
 * @category Core
 */
export declare enum AxisCoupling {
    /**
     * Doesn't couple a {@link ViewportWidget}'s axis to its child; the
     * viewport's axis length is completely separate from the child's axis
     * length.
     *
     * Default axis coupling mode for ViewportWidget.
     */
    None = 0,
    /**
     * Bi-directional coupling. The {@link ViewportWidget}'s axis will be equal
     * to its child's axis. Use this if the axis being tied isn't meant to be
     * scrollable.
     */
    Bi = 1,
    /**
     * Uni-directional coupling, from the parent to the child. The
     * {@link ViewportWidget}'s axis will be resolved as a regular Widget, but
     * the result will be transferred to the child's minimum axis length
     * constraint.
     *
     * Default axis coupling mode for {@link TextArea}.
     */
    ParentToChild = 2,
    /**
     * Uni-directional coupling, from the child to the parent. The child's
     * resolved axis length will be used as the {@link ViewportWidget}'s minimum
     * axis length. Useful when combined with {@link Widget#flexShrink}.
     *
     * Default axis coupling mode for {@link TextArea}.
     */
    ChildToParent = 3
}