com.facebook.litho.sections.annotations

Annotation Type OnViewportChanged

public @interface OnViewportChanged

The method annotated with this annotation will be called when the UI rendering the Section scrolls to a new position.

See communicating-with-the-ui for details.

Example:

  @DiffSectionSpec
  public class MyChangeSetSpec {

   @OnViewportChanged
   protected void onViewportChanged(
     SectionContext c,
     int firstVisiblePosition,
     int lastVisiblePosition,
     int totalCount, // the total count of items this ListComponent is displaying in the list
     int firstFullyVisibleIndex,
     int lastFullyVisibleIndex,
     Service service) { // If any
     if (something(firstVisiblePosition, lastVisiblePosition, totalCount) {
       service.doSomething();
     }
   }
 }
 

This lifecycle method will only be called if either firstVisiblePosition or lastVisiblePosition have changed in response to a scroll event.

See Also:

GroupSectionSpec, DiffSectionSpec