setObserver
public fun Composition.setObserver(observer: CompositionObserver): CompositionObserverHandle?Observe the composition. Calling this twice on the same composition will implicitly dispose the previous observer. the CompositionObserver will be called for this composition and all sub-composition, transitively, for which this composition is a context. If setObserver is called on a sub-composition, it will override the parent composition observer for itself and all its sub-compositions.
The observer is resolved once per composition pass, between CompositionObserver.onBeginComposition and CompositionObserver.onEndComposition. Setting or replacing the observer while a pass is in progress takes effect starting with the next pass.
Parameters
| observer | the observer that will be informed of composition events for this composition and all sub-compositions for which this composition is the composition context. Observing a composition will prevent the parent composition's observer from receiving composition events about this composition. |
Return
a handle that allows the observer to be disposed and detached from the composition. Disposing an observer for a composition with a parent observer will begin sending the events to the parent composition's observer. A null indicates the composition does not support being observed.
