public void setPageMarginDrawable(Drawable d) {
        mMarginDrawable = d;
        if (d != null) refreshDrawableState();
        setWillNotDraw(d == null);
        invalidate();
    }
Set a drawable that will be used to fill the margin between pages.

@param d Drawable to display between pages
dkplayer-sample/src/main/java/xyz/doikki/dkplayer/widget/VerticalViewPager.java