osu-lazer/osu.Game/Database/DatabaseWorkingBeatmap.cs

// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE

using System.IO;
using osu.Framework.Audio.Track;
using osu.Framework.Graphics.Textures;
using osu.Game.Beatmaps;
using osu.Game.Beatmaps.Formats;
using osu.Game.Beatmaps.IO;

namespace osu.Game.Database
{
    internal class DatabaseWorkingBeatmap : WorkingBeatmap
    {
        private readonly BeatmapDatabase database;

        public DatabaseWorkingBeatmap(BeatmapDatabase database, BeatmapInfo beatmapInfo, BeatmapSetInfo beatmapSetInfo, bool withStoryboard = false)
            : base(beatmapInfo, beatmapSetInfo, withStoryboard)
        {
            this.database = database;
        }

        private ArchiveReader getReader() => database?.GetReader(BeatmapSetInfo);
        
        protected override Beatmap GetBeatmap()
        {
            Beatmap beatmap;
            try
            {
                using (var reader = getReader())
                {
                    BeatmapDecoder decoder;
                    using (var stream = new StreamReader(reader.GetStream(BeatmapInfo.Path)))
                    {
                        decoder = BeatmapDecoder.GetDecoder(stream);
                        beatmap = decoder?.Decode(stream);
                    }

                    if (WithStoryboard && beatmap != null && BeatmapSetInfo.StoryboardFile != null)
                        using (var stream = new StreamReader(reader.GetStream(BeatmapSetInfo.StoryboardFile)))
                            decoder.Decode(stream, beatmap);
                }
            }
            catch { return null; }
            return beatmap;
        }
        
        protected override Texture GetBackground()
        {
            Texture background;
            if (BeatmapInfo?.Metadata?.BackgroundFile == null)
                return null;
            try
            {
                using (var reader = getReader())
                {
                    background = new TextureStore(
                        new RawTextureLoaderStore(reader),
                        false).Get(BeatmapInfo.Metadata.BackgroundFile);
                }
            }
            catch { return null; }
            return background;
        }

        private ArchiveReader trackReader;
        protected override Track GetTrack()
        {
            Track track;
            try
            {
                //store a reference to the reader as we may continue accessing the stream in the background.
                trackReader = getReader();
                var trackData = trackReader?.GetStream(BeatmapInfo.Metadata.AudioFile);
                track = trackData == null ? null : new TrackBass(trackData);
            }
            catch { return null; }
            return track;
        }
    }
}