// 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 System.Collections.Generic; namespace osu.Game.Skinning { /// <summary> /// An abstract skin implementation, whose primary purpose is to properly handle component fallback across multiple layers of skins (e.g.: beatmap skin, user skin, default skin). /// </summary> /// <remarks> /// Common usage is to do an initial lookup via <see cref="FindProvider"/>, and use the returned <see cref="ISkin"/> /// to do further lookups for related components. /// /// The initial lookup is used to lock consecutive lookups to the same underlying skin source (as to not get some elements /// from one skin and others from another, which would be the case if using <see cref="ISkin"/> methods like /// <see cref="ISkin.GetSample"/> directly). /// </remarks> public interface ISkinSource : ISkin { /// <summary> /// Fired whenever a source change occurs, signalling that consumers should re-query as required. /// </summary> event Action SourceChanged; /// <summary> /// Find the first (if any) skin that can fulfill the lookup. /// This should be used for cases where subsequent lookups (for related components) need to occur on the same skin. /// </summary> /// <returns>The skin to be used for subsequent lookups, or <c>null</c> if none is available.</returns> ISkin? FindProvider(Func<ISkin, bool> lookupFunction); /// <summary> /// Retrieve all sources available for lookup, with highest priority source first. /// </summary> IEnumerable<ISkin> AllSources { get; } } }