怎么在Android中通过自定义View实现一个抽屉效果

   class MyAnimation extends Animation {    private int viewCurrentLfet;    private int viewStartLfet;    private int viewTargetLfet;    private int viewWidth;    private View view;    private int cha;    public MyAnimation(View view, int viewStartLfet, int viewTargetLfet, int viewWidth) {      this.view = view;      this.viewStartLfet = viewStartLfet;      this.viewTargetLfet = viewTargetLfet;      this.viewWidth = viewWidth;      cha = viewTargetLfet - viewStartLfet;      setDuration(Math.abs(cha));    }    @Override    protected void applyTransformation(float interpolatedTime, Transformation t) {      super.applyTransformation(interpolatedTime, t);      viewCurrentLfet = (int) (viewStartLfet + cha * interpolatedTime);      view.layout(viewCurrentLfet, 0, viewCurrentLfet + viewWidth, menuHeight);    }  }