> Fabio Bracci wrote: > > > a) why is draw() a protected method? > > Because normally the user should not call draw the widgets explicitly, > it is drawn when needed within Fl::flush() - ie within Fl::run() loop. > > HOWEVER draw() of Fl_Widget is public! > So there is nothing to stop you to downcast and access it anyway - like > > ((Fl_Widget *)my_group)->draw(); > > > b) how to trigger draw()? I'm thinking of a group->hide(); group->show() > > sequence, but it seems clumsy to me ... > > You can trigger it by > > my_group->redraw(); > > but there is even better way as above call may make dirty also > particular screen window regions which would need to be redrawn with > next call to Fl::flush() within UI loop. To avoid that, it is better and > faster to only set damage flags using > Fl_Widget::clear_damage(FL_DAMAGE_ALL) call. But we need to assure that > at that moment the screen up-to-date and we do not interfere wit the UI > updating loop - so we will call Fl::flush() first. Aftrer drawing we can > safely clean the the damage flags back. So the code sequence would be: > > Fl::flush(); // now everything should be clean > // and screen is up-to-date > > my_group->clear_damage(FL_DAMAGE_ALL); // makes it dirty > // without destroying regions > > ((Fl_Widget *)my_group)->draw(); // now it should draw just fine > > my_group->clear_damage(0); // makes it clean again > > > Roman
Hi, this indeed worked, forgetting the clear_damage call the system simply crashes ... _______________________________________________ fltk mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk
