改变无边框窗体的尺寸大小和移动无边框窗体

        #region 移动窗体
        Point mouseOff;//鼠标移动位置变量
        bool leftFlag;//标记是否为左键
        private void Form_Home_ShowAlarm_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseOff = new Point(-e.X, -e.Y); //得到变量的值
                leftFlag = true;                  //点击左键按下时标注为true;
            }
        }

        private void Form_Home_ShowAlarm_MouseMove(object sender, MouseEventArgs e)
        {
            if (leftFlag)
            {
                Point mouseSet = Control.MousePosition;
                mouseSet.Offset(mouseOff.X, mouseOff.Y);  //设置移动后的位置
                Location = mouseSet;
            }
        }

        private void Form_Home_ShowAlarm_MouseUp(object sender, MouseEventArgs e)
        {
            if (leftFlag)
            {
                leftFlag = false;//释放鼠标后标注为false;
            }
        }
        #endregion

       # region  无边框窗体的尺寸缩放
        //using System.Runtime.InteropServices;  
        [DllImport("user32.dll")]
        public static extern bool ReleaseCapture();
        [DllImport("user32.dll")]
        public static extern bool SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);

        public static int formResizeMode = 0;       // 此处指定窗体尺寸修改的模式

        // 在Form的MouseDown(object sender, MouseEventArgs e)事件中调用此函数，可调整窗体大小
        public static void MouseDown_ResizeForm(Form form)
        {        //常量
            int WM_SYSCOMMAND = 0x0112;          
            if (formResizeMode == 0) return;    // 若无缩放模式，则返回
            ReleaseCapture();
            SendMessage(form.Handle, WM_SYSCOMMAND, formResizeMode, 0);          
        }
        private void FormParent_MouseDown(object sender, MouseEventArgs e)
        {
            Form from = (Form)sender;
            MouseDown_ResizeForm(from);
        }

        // 在处于最前端的控件的MouseMove事件中调用此函数，根据鼠标位置设置对应的缩放模式
        private void FormParent_MouseMove(object sender, MouseEventArgs e)
        {
            Control ctrl = (Control)sender;             // 获取鼠标处的控件
            Rectangle client = ctrl.ClientRectangle;    // 获取控件尺寸

            setSizeMode(client, new Point(e.X, e.Y), 10);   // 根据鼠标在区域client中的位置设置缩放模式           
        }

        // 根据坐标 x,y 在rect上的位置控制尺寸调节模式
        private static void setSizeMode(Rectangle R, Point P, int W)
        {
            formResizeMode = getSizeMode(R, P, W);
        }

        // 根据坐标 x,y 在rect上的位置控制尺寸调节模式
        private static int getSizeMode(Rectangle R, Point P, int W)
        {
            //改变窗体大小相关参数
            int WMSZ_LEFT = 0xF001;
            int WMSZ_RIGHT = 0xF002;
            int WMSZ_TOP = 0xF003;
            int WMSZ_TOPLEFT = 0xF004;
            int WMSZ_TOPRIGHT = 0xF005;
            int WMSZ_BOTTOM = 0xF006;
            int WMSZ_BOTTOMLEFT = 0xF007;
            int WMSZ_BOTTOMRIGHT = 0xF008;

            // 中间区域
            Rectangle main = new Rectangle(R.Left + W, R.Top + W, R.Width - 2 * W, R.Height - 2 * W);
            if (main.Contains(P)) return 0;

            // 左侧区域
            Rectangle LeftRect = new Rectangle(R.Left + W, R.Top + W, W, R.Height - 2 * W);
            if (LeftRect.Contains(P)) return WMSZ_LEFT;

            // 右侧区域
            Rectangle RightRect = new Rectangle(R.Right - W, R.Top + W, W, R.Height - 2 * W);
            if (RightRect.Contains(P)) return WMSZ_RIGHT;

            // 顶部区域
            Rectangle TopRect = new Rectangle(R.Left + W, R.Top, R.Width - 2 * W, W);
            if (TopRect.Contains(P)) return WMSZ_TOP;

            // 底部区域
            Rectangle BottomRect = new Rectangle(R.Left + W, R.Bottom - W, R.Width - 2 * W, W);
            if (BottomRect.Contains(P)) return WMSZ_BOTTOM;

            // 左上区域
            Rectangle TOPLEFT = new Rectangle(R.Left, R.Top, W, W);
            if (TOPLEFT.Contains(P)) return WMSZ_TOPLEFT;

            // 右上区域
            Rectangle TOPRIGHT = new Rectangle(R.Right - W, R.Top, W, W);
            if (TOPRIGHT.Contains(P)) return WMSZ_TOPRIGHT;

            // 左下区域
            Rectangle BOTTOMLEFT = new Rectangle(R.Left, R.Bottom - W, W, W);
            if (BOTTOMLEFT.Contains(P)) return WMSZ_BOTTOMLEFT;

            // 右下区域
            Rectangle BOTTOMRIGHT = new Rectangle(R.Right - W, R.Bottom - W, W, W);
            if (BOTTOMRIGHT.Contains(P)) return WMSZ_BOTTOMRIGHT;

            return 0;
        }
        //https://blog.csdn.net/scimence/article/details/51511245
        # endregion

//拖动窗体/双击最大化/改变大小（无边框窗体）
//https://blog.csdn.net/szy759590387/article/details/88656971

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