PageStateChangeCallbacks

interface PageStateChangeCallbacks

Implement this to receive state callbacks for ExpandablePageLayout.

onPageAboutToCollapse	`abstract fun onPageAboutToCollapse(collapseAnimDuration: Long): Unit`
onPageAboutToExpand	`abstract fun onPageAboutToExpand(expandAnimDuration: Long): Unit`
onPageCollapsed	`abstract fun onPageCollapsed(): Unit`
onPageExpanded	`abstract fun onPageExpanded(): Unit`

SimplePageStateChangeCallbacks	`abstract class SimplePageStateChangeCallbacks : PageStateChangeCallbacks` Empty implementations of PageStateChangeCallbacks. This way, any custom listener that cares only about a subset of the methods of this listener can subclass this adapter class instead of implementing the interface directly.
UncoveredAreaTintPainter	`open class UncoveredAreaTintPainter : TintPainter, PageStateChangeCallbacks` Draws a tint on InboxRecyclerView only in the area that's not covered by its page. This allows the page content to not have another background of its own, thus reducing overdraw by a level.