using System.Drawing;
using System.Windows.Forms;

namespace OTSIncAReportApp
{
    /// <summary>
    /// 拖拽帮助类，控件需要注册该类中的鼠标相关事件
    /// </summary>
    public class DragHelper
    {
        #region 变量定义
        /// <summary>
        /// 光标状态
        /// </summary>
        private enum EnumMousePointPosition
        {
            StateLess,                               //无状态
            LeftBorderStetch,                          //左边框拉伸
            TopLeftCornerStretch,                   //左上角拉伸
            TopBorderStretch,                       //上边框拉伸
            TopRightCornerStretch,                  //右上角拉伸
            RightBorderStretch,                     //右边框拉伸
            BottomRightCornerStretch,               //右下角拉伸
            BottomBorderStretch,                    //下边框拉伸
            BottomLeftCornerStretch,                //左下角拉伸
            Drag                                    //拖曳
        }

        /// <summary>
        /// 控件原背景色
        /// </summary>
        private static Color oldColor = default(Color);

        /// <summary>
        /// 控件点击时使用的背景色
        /// </summary>
        private static Color controlFocusedBackcolor = Color.Red;

        /// <summary>
        /// 鼠标拖拽使用的原始点
        /// </summary>
        private static Point mouseDragOldPoint = default(Point);

        /// <summary>
        /// 鼠标上一次改变大小后的位置点
        /// </summary>
        private static Point mouseSizeLastPoint = default(Point);

        /// <summary>
        /// 绘制边框的画笔
        /// </summary>
        private static Pen borderPen = new Pen(Color.Black);

        /// <summary>
        /// 光标变化临界的宽度
        /// </summary>
        private const int BAND = 3;

        /// <summary>
        /// 控件最小宽度
        /// </summary>
        private const int MINWIDTH = 10;

        /// <summary>
        /// 控件最小高度
        /// </summary>
        private const int MINHEIGHT = 10;

        /// <summary>
        /// 当前鼠标操作
        /// </summary>
        private static EnumMousePointPosition mousePointPosition = EnumMousePointPosition.StateLess;
        #endregion

        #region 鼠标相关方法
        /// <summary>
        /// 注册控件拖拽事件
        /// </summary>
        /// <param name="ctl">拖拽区域控件</param>
        public static void RegisterDragEvent(Control ctl)
        {
            ctl.MouseDown += DragHelper.DragControl_MouseDown;
            ctl.MouseUp += DragHelper.DragControl_MouseUp;
            ctl.MouseMove += DragHelper.DragControl_MouseMove;
        }

        /// <summary>
        /// 控件鼠标点击事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void DragControl_MouseDown(object sender, MouseEventArgs e)
        {
            Control currentControl = null;
            mouseDragOldPoint = mouseSizeLastPoint = e.Location;                        //保存控件当前位置

            currentControl = sender as Control;
            oldColor = currentControl.BackColor;        //保存背景色，鼠标弹起时恢复
            currentControl.BackColor = controlFocusedBackcolor;    //改变背景色
        }


        /// <summary>
        /// 鼠标在控件上移动事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void DragControl_MouseMove(object sender, MouseEventArgs e)
        {
            Control currentControl = null;

            currentControl = sender as Control;

            if (e.Button != MouseButtons.Left)
            {
                mousePointPosition = GetMousePointPosition(currentControl.Size, e);
                switch (mousePointPosition)
                {
                    case EnumMousePointPosition.LeftBorderStetch:
                    case EnumMousePointPosition.RightBorderStretch:
                        Cursor.Current = Cursors.SizeWE;
                        break;
                    case EnumMousePointPosition.TopBorderStretch:
                    case EnumMousePointPosition.BottomBorderStretch:
                        Cursor.Current = Cursors.SizeNS;
                        break;
                    case EnumMousePointPosition.TopLeftCornerStretch:
                    case EnumMousePointPosition.BottomRightCornerStretch:
                        Cursor.Current = Cursors.SizeNWSE;
                        break;
                    case EnumMousePointPosition.TopRightCornerStretch:
                    case EnumMousePointPosition.BottomLeftCornerStretch:
                        Cursor.Current = Cursors.SizeNESW;
                        break;
                    case EnumMousePointPosition.Drag:
                        Cursor.Current = Cursors.SizeAll;
                        break;
                    default:
                        Cursor.Current = null;
                        break;
                }
                return;
            }

            switch (mousePointPosition)
            {
                case EnumMousePointPosition.Drag:
                    currentControl.Left += e.X - mouseDragOldPoint.X;
                    currentControl.Top += e.Y - mouseDragOldPoint.Y;
                    break;
                case EnumMousePointPosition.BottomBorderStretch:
                    currentControl.Height += e.Y - mouseSizeLastPoint.Y;
                    mouseSizeLastPoint = e.Location;                    //记录光标拖动的当前点
                    break;
                case EnumMousePointPosition.BottomRightCornerStretch:
                    currentControl.Width += e.X - mouseSizeLastPoint.X;
                    currentControl.Height = e.Y - mouseSizeLastPoint.Y;
                    mouseSizeLastPoint = e.Location;                    //记录光标拖动的当前点
                    break;
                case EnumMousePointPosition.RightBorderStretch:
                    currentControl.Width += e.X - mouseSizeLastPoint.X;
                    mouseSizeLastPoint = e.Location;                    //记录光标拖动的当前点
                    break;
                case EnumMousePointPosition.TopBorderStretch:
                    currentControl.Top += e.Y - mouseDragOldPoint.Y;
                    currentControl.Height -= e.Y - mouseDragOldPoint.Y;
                    break;
                case EnumMousePointPosition.LeftBorderStetch:
                    currentControl.Left += e.X - mouseDragOldPoint.X;
                    currentControl.Width -= e.X - mouseDragOldPoint.X;
                    break;
                case EnumMousePointPosition.BottomLeftCornerStretch:
                    currentControl.Left += e.X - mouseDragOldPoint.X;
                    currentControl.Width -= e.X - mouseDragOldPoint.X;
                    currentControl.Height += e.Y - mouseSizeLastPoint.Y;
                    mouseSizeLastPoint = e.Location;                    //记录光标拖动的当前点
                    break;
                case EnumMousePointPosition.TopRightCornerStretch:
                    currentControl.Top += e.Y - mouseDragOldPoint.Y;
                    currentControl.Width += e.X - mouseSizeLastPoint.X;
                    currentControl.Height -= e.Y - mouseDragOldPoint.Y;
                    mouseSizeLastPoint = e.Location;                    //记录光标拖动的当前点
                    break;
                case EnumMousePointPosition.TopLeftCornerStretch:
                    currentControl.Left += e.X - mouseDragOldPoint.X;
                    currentControl.Top += e.Y - mouseDragOldPoint.Y;
                    currentControl.Width -= e.X - mouseDragOldPoint.X;
                    currentControl.Height -= e.Y - mouseDragOldPoint.Y;
                    break;
                default: break;
            }
            if (currentControl.Width < MINWIDTH)
            {
                currentControl.Width = MINWIDTH;
            }
            if (currentControl.Height < MINHEIGHT)
            {
                currentControl.Height = MINHEIGHT;
            }
        }


        /// <summary>
        /// 控件鼠标弹起事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void DragControl_MouseUp(object sender, MouseEventArgs e)
        {
            Control currentControl = null;

            currentControl = sender as Control;
            Cursor.Current = null;
            mousePointPosition = EnumMousePointPosition.StateLess;
            currentControl.BackColor = oldColor;                     //恢复控件背景色
        }
        /// <summary>
        /// 获取鼠标位置
        /// </summary>
        /// <param name="size">控件大小</param>
        /// <param name="e">鼠标位置</param>
        /// <returns>鼠标光标位置</returns>
        private static EnumMousePointPosition GetMousePointPosition(Size size, MouseEventArgs e)
        {
            if ((e.X < (-1 * BAND)) || (e.X > size.Width) || (e.Y < (-1 * BAND)) || (e.Y > size.Height))//光标越界
            {
                return EnumMousePointPosition.StateLess;
            }

            if (e.X < BAND)
            {
                if (e.Y < BAND)
                {
                    return EnumMousePointPosition.TopLeftCornerStretch;
                }
                else
                {
                    if (e.Y > ((-1 * BAND) + size.Height))
                    {
                        return EnumMousePointPosition.BottomLeftCornerStretch;
                    }
                    else
                    {
                        return EnumMousePointPosition.LeftBorderStetch;
                    }
                }
            }
            else
            {
                if (e.X > (-1 * BAND + size.Width))
                {
                    if (e.Y < BAND)
                    {
                        return EnumMousePointPosition.TopRightCornerStretch;
                    }
                    else
                    {
                        if (e.Y > (-1 * BAND + size.Height))
                        {
                            return EnumMousePointPosition.BottomRightCornerStretch;
                        }
                        else
                        {
                            return EnumMousePointPosition.RightBorderStretch;
                        }
                    }
                }
                else
                {
                    if (e.Y < BAND)
                    {
                        return EnumMousePointPosition.TopBorderStretch;
                    }
                    else
                    {
                        if (e.Y > (-1 * BAND + size.Height))
                        {
                            return EnumMousePointPosition.BottomBorderStretch;
                        }
                        else
                        {
                            return EnumMousePointPosition.Drag;
                        }
                    }
                }
            }
        }

        #endregion

        #region 绘制相关
        /// <summary>
        /// 绘制控件边框
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private static void DragControlParent_Paint(object sender, PaintEventArgs e)
        {
            Control currentControl = null;

            currentControl = sender as Control;
            return;
        }
        #endregion

    }
}