转动指针，转动拨盘

初始效果图（左）， 转动指针效果图（中），转动拨盘效果图（右）

 代码如下：

        int centerX = 124;
        int centerY = 124;
        private void Form1_Load(object sender, EventArgs e)
        {
            var bmp = GetPointerImg(Resources.valsalvaThresholdPointer, 90f, pictureBox1.Width, pictureBox1.Height, centerX, centerY);
            pictureBox1.Image = bmp;
            lb_currentScale.Text = currentScale.ToString();
        }

        bool mouseMoved = false;
        int currentScale = 5;//当前刻度，取值范围[0,5]
        int moveStartX = int.MinValue;
        int moveStartY = int.MinValue;
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            moveStartX = e.X;
            moveStartY = e.Y;
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            mouseMoved = true;
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            if (!mouseMoved || (moveStartX == int.MinValue && moveStartY == int.MinValue)) return;//拖动才绘制

            mouseMoved = false;
            Console.WriteLine($"X:{e.X}-{moveStartX},Y:{e.Y}-{moveStartY}");

            //计算刻度步进
            int addition = 1;
            //以变化大的为准
            if (Math.Abs(e.Y - moveStartY) > Math.Abs(e.X - moveStartX)) addition = e.X.CompareTo(centerX) * moveStartY.CompareTo(e.Y);//中心点右方，↑为正，左方↓为正
            else addition = e.Y.CompareTo(centerY) * e.X.CompareTo(moveStartX);//中心点上方，←为正，下方→为正

            float currentAngle = (5 - currentScale) * 18;//当前角度,每个刻度 90/5 度
            Console.WriteLine($"currentAngle:{currentAngle},addition:{addition}");
            currentScale += addition;
            if (currentScale > 5 || currentScale < 0)
            {
                currentScale -= addition;
            }
            else if (addition != 0)
            {
                //1.5秒内过渡到下一个刻度
                Task.Run(() =>
                {                                       
                    //帧率24，1.5秒共36帧，每帧 1000/24 毫秒
                    for (int i = 0; i < 36; i++)
                    {
                        currentAngle -= addition * 0.5f;//角度变化和刻度相反，每帧 18/36 度
                        var bmp = GetPieImg(Resources.valsalvaThresholdPie, currentAngle, centerX, centerY);
                        pictureBox1.BackgroundImage = bmp;
                        Thread.Sleep(42);
                    }
                });

                lb_currentScale.Text = currentScale.ToString();
            }

            moveStartX = int.MinValue;
            moveStartY = int.MinValue;
        }

        private Bitmap GetPieImg(Bitmap pieImg, float angle, int centerX, int centerY)
        {
            // 创建新的位图作为旋转后的图片
            Bitmap rotatedImage = new Bitmap(pieImg.Width, pieImg.Height);

            // 创建一个Graphics对象，用于绘制旋转后的图片
            using (Graphics g = Graphics.FromImage(rotatedImage))
            {
                // 设置旋转中心点为图片中心
                g.TranslateTransform(centerX, centerY);

                // 执行旋转
                g.RotateTransform(angle);

                // 恢复旋转中心点到原位置
                g.TranslateTransform(-centerX, -centerY);

                g.DrawImage(pieImg, Point.Empty);
            }
            return rotatedImage;
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            if (moveStartX != int.MinValue) return;
            var ea = (MouseEventArgs)e;
            double distance = Math.Sqrt(Math.Pow(ea.X - centerX, 2) + Math.Pow(ea.Y - centerY, 2));//点击处到圆心的距离
            double angle = Math.Asin((centerY - ea.Y) / distance) * 180 / Math.PI;
            if (centerX < ea.X && centerY > ea.Y) angle = 180- angle;//第一象限
            else if (centerX > ea.X && centerY < ea.Y) angle = 0;//第三象限
            else if (centerX < ea.X && centerY < ea.Y) angle = 180;//第四象限
            text_Angle.Text = angle.ToString("f3");
            var bmp = GetPointerImg(Resources.valsalvaThresholdPointer, (float)angle, pictureBox1.Width, pictureBox1.Height, centerX, centerY);
            pictureBox1.Image = bmp;
        }

        private void btn_DrawPointer_Click(object sender, EventArgs e)
        {
            var angle = Convert.ToDouble(text_Angle.Text);
            var bmp = GetPointerImg(Resources.valsalvaThresholdPointer, (float)angle, pictureBox1.Width, pictureBox1.Height, centerX, centerY);
            pictureBox1.Image = bmp;
        }

        private Bitmap GetPointerImg(Bitmap pointerImg, float angle, int w, int h, int centerX, int centerY)
        {
            // 创建新的位图作为旋转后的图片
            Bitmap rotatedImage = new Bitmap(w, h);

            // 创建一个Graphics对象，用于绘制旋转后的图片
            using (Graphics g = Graphics.FromImage(rotatedImage))
            {
                g.FillEllipse(new SolidBrush(Color.Red), new Rectangle(centerX - 5, centerY - 5, 10, 10));

                // 设置旋转中心点为图片中心
                g.TranslateTransform(centerX, centerY);

                // 执行旋转
                g.RotateTransform(angle);

                // 恢复旋转中心点到原位置
                g.TranslateTransform(-centerX, -centerY);

                g.DrawImage(pointerImg, 0, centerY - pointerImg.Height / 2);
            }
            return rotatedImage;
        }