private void checkLayout ( ) { Dimension dim = getLayoutDimension ( ) ; if ( currentDimension == null || ! currentDimension . equals ( dim ) ) //the dimension has changed { createLayout ( dim ) ; //containing box for the new viewport viewport . setContainingBlockBox ( owner ) ; if ( owner instanceof BlockBox ) viewport . clipByBlock ( ( BlockBox ) owner ) ; owner . removeAllSubBoxes ( ) ; owner . addSubBox ( viewport ) ; currentDimension = new Dimension ( dim ) ; } }
Checks whether the layout is computed and recomputes it when necessary .