如何用动画绘制路径？

Question

green_paintbrush_stroke = new Paint();
green_paintbrush_stroke.setColor(Color.GREEN);
green_paintbrush_stroke.setStyle(Paint.Style.STROKE);
green_paintbrush_stroke.setStrokeWidth(10);

tik = new Path();
tik.moveTo(25,50);
tik.lineTo(50,100);
tik.moveTo(50,100);
tik.lineTo(100,-1);

我想用动画持续时间绘制mypath。你能帮帮我吗？