PurplePen.RectCourseObj.MoveHandle C# (CSharp) Method

        public override void MoveHandle(PointF oldHandle, PointF newHandle)
        {
            PointF[] handles = GetHandles();
            int handleIndex = Array.IndexOf(handles, oldHandle);

            // Existing coordinates of the rectangle.
            float left = rect.Left, top = rect.Top, right = rect.Right, bottom = rect.Bottom;

            // Figure out which coord(s) moving this handle changes.
            bool changeLeft = false, changeTop = false, changeRight = false, changeBottom = false;
            switch (handleIndex) {
            case 0: changeLeft = true; changeTop = true; break;
            case 1: changeTop = true; break;
            case 2: changeRight = true; changeTop = true; break;
            case 3: changeLeft = true; break;
            case 4: changeRight = true; break;
            case 5: changeLeft = true; changeBottom = true; break;
            case 6: changeBottom = true; break;
            case 7: changeRight = true; changeBottom = true; break;
            default:
                Debug.Fail("bad handle"); break;
            }

            // Update the coordinates based on movement.
            if (changeLeft)         left = newHandle.X;
            if (changeTop)          top = newHandle.Y;
            if (changeRight)       right = newHandle.X;
            if (changeBottom)    bottom = newHandle.Y;

            RectangleF newRect = Geometry.RectFromPoints(left, top, right, bottom);

            // Update the rectangle.
            RectangleUpdating(ref newRect, false, changeLeft, changeTop, changeRight, changeBottom);
            rect = newRect;
        }