osu-lazer/osu.Game/Modes/Replays/FramedReplay.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;
using System.Collections.Generic;
using osu.Framework.Extensions.IEnumerableExtensions;
using osu.Framework.Input;
using osu.Framework.MathUtils;
using osu.Game.Input.Handlers;
using OpenTK;
using OpenTK.Input;
using KeyboardState = osu.Framework.Input.KeyboardState;
using MouseState = osu.Framework.Input.MouseState;

namespace osu.Game.Modes.Replays
{
    public abstract class FramedReplay : Replay
    {
        protected List<ReplayFrame> Frames = new List<ReplayFrame>();

        public override ReplayInputHandler CreateInputHandler() => new FramedReplayInputHandler(Frames);

        /// <summary>
        /// The ReplayHandler will take a replay and handle the propagation of updates to the input stack.
        /// It handles logic of any frames which *must* be executed.
        /// </summary>
        public class FramedReplayInputHandler : ReplayInputHandler
        {
            private readonly List<ReplayFrame> replayContent;

            public ReplayFrame CurrentFrame => !hasFrames ? null : replayContent[currentFrameIndex];
            public ReplayFrame NextFrame => !hasFrames ? null : replayContent[nextFrameIndex];

            private int currentFrameIndex;

            private int nextFrameIndex => MathHelper.Clamp(currentFrameIndex + (currentDirection > 0 ? 1 : -1), 0, replayContent.Count - 1);

            public FramedReplayInputHandler(List<ReplayFrame> replayContent)
            {
                this.replayContent = replayContent;
            }

            private bool advanceFrame()
            {
                int newFrame = nextFrameIndex;

                //ensure we aren't at an extent.
                if (newFrame == currentFrameIndex) return false;

                currentFrameIndex = newFrame;
                return true;
            }

            public void SetPosition(Vector2 pos)
            {
            }

            private Vector2? position
            {
                get
                {
                    if (!hasFrames)
                        return null;

                    return Interpolation.ValueAt(currentTime, CurrentFrame.Position, NextFrame.Position, CurrentFrame.Time, NextFrame.Time);
                }
            }

            public override List<InputState> GetPendingStates()
            {
                var buttons = new HashSet<MouseButton>();
                if (CurrentFrame?.MouseLeft ?? false)
                    buttons.Add(MouseButton.Left);
                if (CurrentFrame?.MouseRight ?? false)
                    buttons.Add(MouseButton.Right);

                return new List<InputState>
                {
                    new InputState
                    {
                        Mouse = new ReplayMouseState(ToScreenSpace(position ?? Vector2.Zero), buttons),
                        Keyboard = new ReplayKeyboardState(new List<Key>())
                    }
                };
            }

            public bool AtLastFrame => currentFrameIndex == replayContent.Count - 1;
            public bool AtFirstFrame => currentFrameIndex == 0;

            public Vector2 Size => new Vector2(512, 384);

            private const double sixty_frame_time = 1000.0 / 60;

            private double currentTime;
            private int currentDirection;

            /// <summary>
            /// When set, we will ensure frames executed by nested drawables are frame-accurate to replay data.
            /// Disabling this can make replay playback smoother (useful for autoplay, currently).
            /// </summary>
            public bool FrameAccuratePlayback = true;

            private bool hasFrames => replayContent.Count > 0;

            private bool inImportantSection =>
                FrameAccuratePlayback &&
                //a button is in a pressed state
                ((currentDirection > 0 ? CurrentFrame : NextFrame)?.IsImportant ?? false) &&
                //the next frame is within an allowable time span
                Math.Abs(currentTime - NextFrame?.Time ?? 0) <= sixty_frame_time * 1.2;

            /// <summary>
            /// Update the current frame based on an incoming time value.
            /// There are cases where we return a "must-use" time value that is different from the input.
            /// This is to ensure accurate playback of replay data.
            /// </summary>
            /// <param name="time">The time which we should use for finding the current frame.</param>
            /// <returns>The usable time value. If null, we should not advance time as we do not have enough data.</returns>
            public override double? SetFrameFromTime(double time)
            {
                currentDirection = time.CompareTo(currentTime);
                if (currentDirection == 0) currentDirection = 1;

                if (hasFrames)
                {
                    //if we changed frames, we want to execute once *exactly* on the frame's time.
                    if (currentDirection == time.CompareTo(NextFrame.Time) && advanceFrame())
                        return currentTime = CurrentFrame.Time;

                    //if we didn't change frames, we need to ensure we are allowed to run frames in between, else return null.
                    if (inImportantSection)
                        return null;
                }

                return currentTime = time;
            }

            protected class ReplayMouseState : MouseState
            {
                public ReplayMouseState(Vector2 position, IEnumerable<MouseButton> list)
                {
                    Position = position;
                    list.ForEach(b => PressedButtons.Add(b));
                }
            }

            protected class ReplayKeyboardState : KeyboardState
            {
                public ReplayKeyboardState(List<Key> keys)
                {
                    Keys = keys;
                }
            }
        }
    }
}