Winform鼠标拖动改变控件大小、移动控件位置

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/beibeisong/article/details/50419272

基本逻辑：

1、鼠标移动过程（未按下鼠标左键）进行边界检测，当移动到控件边界时（某范围内），改变显示的光标；

2、此时，若按下鼠标左键（也可是右键），记录鼠标的位置和控件的大小；

3、按下鼠标左键移动过程中，改变控件的大小（三个方向）或者location（五个方向）；

4、逻辑完善：进行边界检测；

5、编写为自己的类，可以用于初始化控件使其具有鼠标拖动改变大小的功能。

数据准备：方向枚举，用于记录方向

public enum MouseDirection
    {
        East,
        West,
        South,
        North,
        Southeast,
        Southwest,
        Northeast,
        Northwest,
        None
    }

鼠标移动：这列出了四个方向分别为东南、西北、西南、东北

if (e.Location.X >= control.Width - 5 && e.Location.Y >= control.Height - 5 )
                {
                    control.Cursor = Cursors.SizeNWSE;
                    direction = MouseDirection.Southeast;
                }
                else if (e.Location.X <= 5 && e.Location.Y <= 5 )
                {
                    control.Cursor = Cursors.SizeNWSE;
                    direction = MouseDirection.Northwest;
                }
                else if (e.Location.X <= 5 && e.Location.Y >= control.Height - 5 )
                {
                    control.Cursor = Cursors.SizeNESW;
                    direction = MouseDirection.Southwest;
                }
                else if (e.Location.X >= control.Width - 5 && e.Location.Y <= 5 )
                {
                    control.Cursor = Cursors.SizeNESW;
                    direction = MouseDirection.Northeast;
                }

点击左键，记录信息

if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint = e.Location;
                oldSize = control.Size;
            }

按下左键移动

            if (e.Button == MouseButtons.Left)
            {
                if (direction != MouseDirection.None)//改变大小
                {
                    Point oldLocation = control.Location;
                    ResizeControl(e.Location);//改变大小的方法
                    if (EventControlResize != null)//自定义改变大小事件
                        EventControlResize(new ControlInfo(control.Location, oldLocation, control.Size, oldSize, direction));
                }
                else//移动位置
                {
                    Point oldLocation = control.Location;
                    control.Cursor = Cursors.SizeAll;
                    Point location = GetPointToParent(new Point(e.Location.X - mouseDownPoint.X, e.Location.Y - mouseDownPoint.Y));
                    RelocationControl(location);//改变位置的方法
                    if (EventControlLocationChanged != null)//自定义改变位置事件
                        EventControlLocationChanged(new ControlInfo(control.Location, oldLocation, control.Size, oldSize, direction));
                }
            }

改变东南（右下）方向，control为拖动的控件，direction为方向，高和宽分开计算，最小值为10，最大值为右和下到达父容器边界

private void ResizeControl(Point p)
        {
            Point mousePosition = GetPointToParent(p);//将控件内坐标转换为父容器坐标
            Point location = control.Location;
            if (direction == MouseDirection.Southeast)//东南
            {
                control.Cursor = Cursors.SizeNWSE;
                if (mousePosition.X - control.Left <= 10)
                {
                    mousePosition.X = control.Left + 10;
                    control.Width = 10;
                }
                else if (mousePosition.X - control.Left >= control.Parent.Width - control.Left)
                {
                    mousePosition.X = control.Parent.Width;
                    control.Width = control.Parent.Width - control.Left;
                }
                else
                {
                    control.Width = mousePosition.X - control.Left;
                }
                if (mousePosition.Y - control.Top <= 10)
                {
                    mousePosition.Y = control.Top + 10;
                    control.Height = 10;
                }
                else if (mousePosition.Y - control.Top >= control.Parent.Height - control.Top)
                {
                    mousePosition.Y = control.Parent.Height;
                    control.Height = control.Parent.Height - control.Top;
                }
                else
                {
                    control.Height = mousePosition.Y - control.Top;
                }
            }

}

 改变位置的方法

private void RelocationControl(Point location)
        {
            if (location.X < 0)
            {
                location.X = 0;
            }
            else if (location.X > control.Parent.Width - control.Width)
            {
                location.X = control.Parent.Width - control.Width;
            }
            if (location.Y < 0)
            {
                location.Y = 0;
            }
            else if (location.Y > control.Parent.Height - control.Height)
            {
                location.Y = control.Parent.Height - control.Height;
            }
            control.Location = location;
            //control.Parent.Refresh();
        }