// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
using UnityEngine.EventSystems;
namespace Microsoft.MixedReality.Toolkit.Input
{
///
/// Interface to implement to react to focus changed events.
///
///
/// The events on this interface are related to those of , whose event have
/// a known ordering with this interface:
/// IMixedRealityFocusChangedHandler::OnBeforeFocusChange
/// IMixedRealityFocusHandler::OnFocusEnter
/// IMixedRealityFocusHandler::OnFocusExit
/// IMixedRealityFocusChangedHandler::OnFocusChanged
/// Because these two interfaces are different, consumers must be wary about having nested
/// hierarchies where some game objects will implement both interfaces, and more deeply nested
/// object within the same parent-child chain that implement a single one of these - such
/// a presence can lead to scenarios where one interface is invoked on the child object, and then
/// the other interface is invoked on the parent object (thus, the parent would "miss" getting
/// the event that the child had already processed).
///
public interface IMixedRealityFocusChangedHandler : IEventSystemHandler
{
///
/// Focus event that is raised before the focus is actually changed.
///
/// Useful for logic that needs to take place before focus changes.
void OnBeforeFocusChange(FocusEventData eventData);
///
/// Focus event that is raised when the focused object is changed.
///
void OnFocusChanged(FocusEventData eventData);
}
}