一、定义缓动动画类

public class AnimationHelper
    {
        Timer animationTimer = new Timer();
        double velocity = 0.0;
        Point location = Point.Empty;
        double force = 0.01; //0.69;
        double drag = 0.8;
        private Control control;
        //private AxShockwaveFlash control;
        private int targetPos=0;

        public AnimationHelper(int interval=5)
        {
            animationTimer.Interval = interval;
            animationTimer.Tick += delegate
            {
                if (control == null) return;
                int currentPos = control.Location.X;
                if (Math.Abs(currentPos - targetPos) <= 5)
                {
                    control.Location = new Point(targetPos, control.Location.Y);
                    animationTimer.Stop();
                }
                int dx = targetPos - currentPos;
                velocity += force * dx;
                velocity *= drag;
                if (Math.Abs(velocity) < 5)
                {
                    if (velocity > 0)
                        velocity = 5;
                    else
                        velocity = -5;
                }
                control.Location = new Point(currentPos + (int)velocity, control.Location.Y);
            };
            animationTimer.Start();
        }

        public void MoveXEx(Control control, int targetPos, Action completeWith = null)
        {
            this.control = control;
            this.targetPos = targetPos;
            velocity = 0;
            animationTimer.Start();
        }
    }

        AnimationHelper animationHelper = new AnimationHelper();
        AnimationHelper animationHelper1 = new AnimationHelper();
        private int pos = 0;
        private int pos1 = 0;
        private int dx = 200;
        private void button1_Click(object sender, EventArgs e)
        {
            animationHelper.MoveXEx(pictureBox2, pos += dx);
            animationHelper1.MoveXEx(pictureBox1, pos1 += dx);
           
        }

        private void button2_Click(object sender, EventArgs e)
        {
            animationHelper.MoveXEx(pictureBox2, pos -= dx);           
            animationHelper1.MoveXEx(pictureBox1, pos1 -= dx);
        }