/// <summary>
/// 拖拽状态
/// </summary>
public enum DragState
{
    /// <summary>
    /// 拖拽开始
    /// </summary>
    DragStart,
    /// <summary>
    /// 拖拽中
    /// </summary>
    DragMove,
    /// <summary>
    /// 拖拽结束
    /// </summary>
    DragEnd
}