Recompute internally what needs be done for the next onDraw.
This function MUST have been called before calling onDraw and getDirtyRectangle.
This method exists to allow the Window to recompute these draw lists less.
And because cache invalidation was easier on user code than internally in the UI.
Important: once you've called recomputeDirtyAreas() you COMMIT to redraw the
corresponding area given by getDirtyRectangle().
IMPORTANT: Two calls to recomputeDirtyAreas() will not yield the same area.
VERY IMPORTANT: See the above note about concurrent calls.
Recompute internally what needs be done for the next onDraw. This function MUST have been called before calling onDraw and getDirtyRectangle. This method exists to allow the Window to recompute these draw lists less. And because cache invalidation was easier on user code than internally in the UI. Important: once you've called recomputeDirtyAreas() you COMMIT to redraw the corresponding area given by getDirtyRectangle(). IMPORTANT: Two calls to recomputeDirtyAreas() will not yield the same area. VERY IMPORTANT: See the above note about concurrent calls.