问Flex 4生命周期和手工绘图

EN

private var dataSourceValid = true;

public function set dataSource(value:FooData):void {
    _dataSource = foo;
    dataSourceValid = false;
    invalidateProperties();
}

override protected function commitProperties():void {

    if (!dataSourceValid)
        commitDataSource();

    // Do it later in case we've invalidated something 
    // belonging to Flex while validating our stuff
    super.commitProperties();
}

protected function commitDataSource():void {

    // Do whatever we need to with our datasource, 
    // including adding or removing child elements.

    // ...

    // If we also need to re-draw something, then
    // invalidateDisplayList();

    dataSourceValid = true;
}