如何制作类似feedly android应用的垂直动画

Question

我正在使用垂直视图分页，但它不像feedly android应用程序一样平滑。我不知道feedly使用的是什么组件。

任何帮助都将不胜感激。

公共类VerticalViewPager扩展了ViewPager {

public VerticalViewPager(Context context) {
    super(context);
    init();
}

public VerticalViewPager(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
}

private void init() {
    // The majority of the magic happens here
    setPageTransformer(true, new VerticalPageTransformer());
    // The easiest way to get rid of the overscroll drawing that happens on the left and right
    setOverScrollMode(OVER_SCROLL_NEVER);
}

private class VerticalPageTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = .75f;
    @Override
    public void transformPage(View view, float position) {

        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(0);

        }  else if (position <= 0) { // [-1,0]
            // Use the default slide transition when moving to the left page
            view.setAlpha(1);
            // Counteract the default slide transition
            view.setTranslationX(view.getWidth() * -position);

            //set Y position to swipe in from top
            float yPosition = position * view.getHeight();
            view.setTranslationY(yPosition);
            view.setScaleX(1);
            view.setScaleY(1);

        } else if (position <= 1) { // [0,1]
            view.setAlpha(1);

            // Counteract the default slide transition
            view.setTranslationX(view.getWidth() * -position);


            // Scale the page down (between MIN_SCALE and 1)
            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);

        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(0);
        }
    }
}


/*private class VerticalPageTransformer implements ViewPager.PageTransformer {

    @Override
    public void transformPage(View view, float position) {

        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(0);

        } else if (position <= 1) { // [-1,1]
            view.setAlpha(1);

            // Counteract the default slide transition
            view.setTranslationX(view.getWidth() * -position);

            //set Y position to swipe in from top
            float yPosition = position * view.getHeight();
            view.setTranslationY(yPosition);

        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(0);
        }
    }
}*/

/**
 * Swaps the X and Y coordinates of your touch event.
 */
private MotionEvent swapXY(MotionEvent ev) {
    float width = getWidth();
    float height = getHeight();

    float newX = (ev.getY() / height) * width;
    float newY = (ev.getX() / width) * height;

    ev.setLocation(newX, newY);

    return ev;
}

@Override
public boolean onInterceptTouchEvent(MotionEvent ev){
    boolean intercepted = super.onInterceptTouchEvent(swapXY(ev));
    swapXY(ev); // return touch coordinates to original reference frame for any child views
    return intercepted;
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
    //return super.onTouchEvent(swapXY(ev));
    final boolean toHandle = super.onTouchEvent(swapXY(ev));
    // Return MotionEvent to normal
    swapXY(ev);
    return toHandle;
}


@Override
public boolean canScrollVertically(int direction) {
    return true;
}


@Override
public boolean canScrollHorizontally(int direction) {
    return false;
}

}