System.Windows.Forms.ColorPickerForm.BrightnessSaturationPicker.OnMouseMove C# (CSharp) Method

            protected override void OnMouseMove(MouseEventArgs e)
            {
                if (_mouseDown)
                {
                    Brightness = (float)(Height - e.Y) / Height;
                    Saturation = (float)e.X / Width;
                    if (Brightness < 0) Brightness = 0;
                    if (Brightness > 1) Brightness = 1;
                    if (Saturation < 0) Saturation = 0;
                    if (Saturation > 1) Saturation = 1;
                }
            }
            protected override void OnMouseUp(MouseEventArgs e)