@Override
    protected void onLayout(boolean flag, int i, int j, int k, int l) {
        layoutChildren();
    }
This layout view for "Pull to Refresh(Ptr)" support all of the view, you can contain everything you want.
support: pull to refresh / release to refresh / auto refresh / keep header view while refreshing / hide header view while refreshing
It defines {@link PtrUIHandler}, which allows you customize the UI easily.
common/src/main/java/com/sxjs/common/widget/pulltorefresh/PtrFrameLayout.java