// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence. // See the LICENCE file in the repository root for full licence text. using System; using osu.Framework.Allocation; using osu.Game.Rulesets.Objects; namespace osu.Game.Screens.Edit { /// <summary> /// Interface for a component that manages changes in the <see cref="Editor"/>. /// </summary> [Cached] public interface IEditorChangeHandler { /// <summary> /// Fired whenever a state change occurs. /// </summary> event Action? OnStateChange; /// <summary> /// Begins a bulk state change event. <see cref="EndChange"/> should be invoked soon after. /// </summary> /// <remarks> /// This should be invoked when multiple changes to the <see cref="Editor"/> should be bundled together into one state change event. /// When nested invocations are involved, a state change will not occur until an equal number of invocations of <see cref="EndChange"/> are received. /// </remarks> /// <example> /// When a group of <see cref="HitObject"/>s are deleted, a single undo and redo state change should update the state of all <see cref="HitObject"/>. /// </example> void BeginChange(); /// <summary> /// Ends a bulk state change event. /// </summary> /// <remarks> /// This should be invoked as soon as possible after <see cref="BeginChange"/> to cause a state change. /// </remarks> void EndChange(); /// <summary> /// Immediately saves the current <see cref="Editor"/> state. /// Note that this will be a no-op if there is a change in progress via <see cref="BeginChange"/>. /// </summary> void SaveState(); /// <summary> /// Restores an older or newer state. /// </summary> /// <param name="direction">The direction to restore in. If less than 0, an older state will be used. If greater than 0, a newer state will be used.</param> void RestoreState(int direction); } }