nl_tokens: Helper method which just calls scrollTo () in the correct scrolling direction .
pl_tokens: protected final void setHeaderScroll ( int value ) { if ( DEBUG ) { Log . d ( LOG_TAG , "setHeaderScroll: " + value ) ; } // Clamp value to with pull scroll range final int maximumPullScroll = getMaximumPullScroll ( ) ; value = Math . <mask> ( maximumPullScroll , Math . max ( - maximumPullScroll , value ) ) ; if ( mLayoutVisibilityChangesEnabled ) { if ( value < 0 ) { mHeaderLayout . setVisibility ( View . VISIBLE ) ; } else if ( value > 0 ) { mFooterLayout . setVisibility ( View . VISIBLE ) ; } else { mHeaderLayout . setVisibility ( View . INVISIBLE ) ; mFooterLayout . setVisibility ( View . INVISIBLE ) ; } } if ( USE_HW_LAYERS ) { /**
  			 * Use a Hardware Layer on the Refreshable View if we've scrolled at
  			 * all. We don't use them on the Header/Footer Views as they change
  			 * often, which would negate any HW layer performance boost.
  			 */ ViewCompat . setLayerType ( mRefreshableViewWrapper , value != 0 ? View . LAYER_TYPE_HARDWARE : View . LAYER_TYPE_NONE ) ; } switch ( getPullToRefreshScrollDirection ( ) ) { case VERTICAL : scrollTo ( 0 , value ) ; break ; case HORIZONTAL : scrollTo ( value , 0 ) ; break ; } }