【每日一题】鼠标左键移动改变位置的方法

基本逻辑：

1、用于边界检测的鼠标移动过程（无需按鼠标左键），当移至控制边界（在一定范围内）时，更改显示的光标；

2、这时，如果您按下鼠标左键（或右键），请记录鼠标的位置和控件的大小；

3、在按住鼠标左键的同时更改控件的大小（三个方向）或位置（五个方向）；

4、完整的逻辑：边界检测；

5、作为其自己的类编写，可用于初始化控件以具有通过拖动鼠标来更改大小的功能。

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：列出了四个方向：东南，西北，西南和东北

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;
                }

单击左键以记录信息

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

按左键移动

            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));
                }
            }

更改东南（右下）方向，控件为拖动控件，方向为方向，高度和宽度分别计算，最小值为10，最大值为到达边界的右下方父容器的

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;
                }
            }

}

如何更改位置

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();
        }

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