YwxAppWpfBarrage/YwxAppWpfDanMu/Controls/DanMuPool.cs

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Animation;
using System.Windows.Threading;
using YwxAppWpfDanMu.Models;

namespace YwxAppWpfDanMu.Controls
{
    internal class DanMuPool
    {
        private readonly DanMuControl _parent;
        private readonly Queue<DanMuMessage> _messageQueue = new Queue<DanMuMessage>();
        private readonly DispatcherTimer _timer;
        private readonly Random _random = new Random();

        public DanMuPool(DanMuControl parent)
        {
            _parent = parent ?? throw new ArgumentNullException(nameof(parent));

            _timer = new DispatcherTimer
            {
                Interval = TimeSpan.FromMilliseconds(50)
            };
            _timer.Tick += OnTimerTick;
        }

        public void Start()
        {
            _timer.Start();
        }

        public void Stop()
        {
            _timer.Stop();
        }

        public void AddDanMu(DanMuMessage message)
        {
            lock (_messageQueue)
            {
                _messageQueue.Enqueue(message);
            }
        }

        public void ClearAll()
        {
            lock (_messageQueue)
            {
                _messageQueue.Clear();
            }

            _parent.DanMuCanvas.Children.Clear();
            foreach (var track in _parent._tracks)
            {
                track.ActiveItems.Clear();
                track.AvailablePosition = 0;
            }
        }

        private void OnTimerTick(object sender, EventArgs e)
        {
            if (_parent.IsPaused)
                return;

            lock (_messageQueue)
            {
                while (_messageQueue.Count > 0)
                {
                    var message = _messageQueue.Dequeue();
                    DispatchDanMu(message);
                }
            }
        }

        private void DispatchDanMu(DanMuMessage message)
        {
            // 找到最适合的轨道
            var track = FindBestTrack(message);
            if (track == null)
                return;

            var danMuItem = new DanMuItem(message);
            danMuItem.Click += (s, args) => _parent.OnDanMuItemClick(danMuItem);

            // 测量弹幕宽度
            danMuItem.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
            var itemWidth = danMuItem.DesiredSize.Width;

            // 设置初始位置
            Canvas.SetLeft(danMuItem, _parent.ActualWidth);
            Canvas.SetTop(danMuItem, track.Top + (track.Height - danMuItem.DesiredSize.Height) / 2);

            _parent.DanMuCanvas.Children.Add(danMuItem);
            track.ActiveItems.Add(danMuItem);

            // 创建动画
            var animation = new DoubleAnimation
            {
                From = _parent.ActualWidth,
                To = -itemWidth,
                Duration = TimeSpan.FromSeconds(5 + _random.NextDouble() * 3),
                FillBehavior = FillBehavior.Stop
            };

            animation.Completed += (s, args) =>
            {
                _parent.DanMuCanvas.Children.Remove(danMuItem);
                track.ActiveItems.Remove(danMuItem);
                _parent.OnDanMuItemRemoved(danMuItem);
            };

            // 添加透明度渐变效果
            var opacityAnimation = new DoubleAnimation
            {
                From = 1.0,
                To = 0.2,
                Duration = animation.Duration,
                BeginTime = TimeSpan.FromSeconds(animation.Duration.TimeSpan.TotalSeconds * 0.7)
            };

            danMuItem.BeginAnimation(Canvas.LeftProperty, animation);
            danMuItem.BeginAnimation(UIElement.OpacityProperty, opacityAnimation);

            // 更新轨道可用位置
            track.AvailablePosition = _parent.ActualWidth + itemWidth + 10; // 10为间距
        }

        private DanMuControl.DanMuTrack FindBestTrack(DanMuMessage message)
        {
            if (_parent._tracks.Count == 0)
                return null;

            // 随机选择一个轨道，检查是否有足够空间
            int startIndex = _random.Next(_parent._tracks.Count);
            for (int i = 0; i < _parent._tracks.Count; i++)
            {
                int index = (startIndex + i) % _parent._tracks.Count;
                var track = _parent._tracks[index];

                // 如果轨道上没有弹幕，或者最后一个弹幕已经移动足够远
                if (track.ActiveItems.Count == 0 ||
                    track.AvailablePosition < _parent.ActualWidth * 0.7)
                {
                    return track;
                }
            }

            // 所有轨道都满了，选择最不拥挤的轨道
            return _parent._tracks.OrderBy(t => t.ActiveItems.Count).First();
        }
    }
}