ATMLWorkBench.controls.Knob.OnPaint C# (CSharp) Метод

        protected override void OnPaint(PaintEventArgs e)
        {
            Matrix matrix = new Matrix();
            base.OnPaint(e);

            Pen pen = new Pen( Color.Red, 2 );
            Pen penBlack = new Pen(Color.Black, 1);
            Brush brush = new SolidBrush(Color.Silver);

            Rectangle r = new Rectangle(this.ClientRectangle.Left, this.ClientRectangle.Top, this.ClientRectangle.Width, this.ClientRectangle.Height );
            r.Inflate(-1, -1);
            if( r.Width % 2 != 0 )
                r.Width = r.Width - 1;
            if( r.Height % 2 != 0 )
                r.Height = r.Height - 1;
            Point centerPoint = new Point(r.Width / 2, r.Height / 2);
            int diamaeter = this.ClientRectangle.Width;
            float radius = diamaeter / 2;

            double radians = (rotation-90) * Math.PI / 180;

            e.Graphics.FillEllipse(brush, r );
            e.Graphics.DrawEllipse(penBlack, r);
            r.Inflate(-2, -2);
            e.Graphics.Transform = matrix;
            e.Graphics.DrawLine(pen, (int)( centerPoint.X * Math.Cos(radians) + centerPoint.X ),
                                     (int)( centerPoint.Y * Math.Sin(radians) + centerPoint.Y ),
                                     centerPoint.X,
                                     centerPoint.Y);
        }