monitorsDisplayRect
Indicates whether the framework should notify the View of changes to its visible region as a result of changes to bounds in its ancestor chain. The events for this require monitoring potentially large sets of Views in the hierarchy and the events can be frequent during layout changes. So the default value is false
. But it is useful for things like efficient rendering of sub-portions (i.e. long list-like Views) where the cost is outweighed.
NOTE: the framework does not notify of clipping due to siblings that overlap with a View (or ancestors). That means a View can be notified of a display rect change and still not be visible to the user.