Android: Why 'invalid' region is called so? -

Android: Why 'invalid' region is called so? -

this extension of question what invalid part in android?

what criterion part become 'valid'?

invalid means part contains outdated info , has redrawn during next view.draw() call.

you can invalidate part calling view.invalidate(rect rect) method. method makes supplied rectangle area invalid, during next draw() frame, view have redraw area. 1 time redrawn (right after view.draw() call) part becomes valid again.

calling view.invalidate() makes whole view area invalid. trigger android phone call view.draw() method. schedule draw-request , execute possible.

android android-layout