osu-lazer/osu.Game/Screens/Edit/Compose/ComposeScreen.cs

// 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 osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Game.Skinning;

namespace osu.Game.Screens.Edit.Compose
{
    public class ComposeScreen : EditorScreenWithTimeline
    {
        protected override Drawable CreateMainContent()
        {
            var ruleset = Beatmap.Value.BeatmapInfo.Ruleset?.CreateInstance();

            var composer = ruleset?.CreateHitObjectComposer();

            if (composer != null)
            {
                var beatmapSkinProvider = new BeatmapSkinProvidingContainer(Beatmap.Value.Skin);

                // the beatmapSkinProvider is used as the fallback source here to allow the ruleset-specific skin implementation
                // full access to all skin sources.
                var rulesetSkinProvider = new SkinProvidingContainer(ruleset.CreateLegacySkinProvider(beatmapSkinProvider));

                // load the skinning hierarchy first.
                // this is intentionally done in two stages to ensure things are in a loaded state before exposing the ruleset to skin sources.
                return beatmapSkinProvider.WithChild(rulesetSkinProvider.WithChild(ruleset.CreateHitObjectComposer()));
            }

            return new ScreenWhiteBox.UnderConstructionMessage(ruleset == null ? "This beatmap" : $"{ruleset.Description}'s composer");
        }
    }
}