WPF动画有撕裂和闪烁

Question

我在WPF动画中有撕裂和闪烁的问题。我有一个玩具应用程序来演示这些问题。这款应用程序会在屏幕上呈现方块动画。正方形的边缘显示撕裂，动画作为一个整体感觉不光滑。

穿孔器显示>60fps， ~10mb显存，0 IRTs。

我已经在两台新的高端计算机上尝试了这个，并且都显示了相同的糟糕动画(>1gb vram，四核等)。

SimpleWindow.zip

Answer 1

你确定你的代码是硬件加速的吗?请查看以下列表:http://blogs.msdn.com/b/jgoldb/archive/2010/06/22/software-rendering-usage-in-wpf.aspx

如果是这样的话——考虑到你得到的超级酷的硬件——你可以尝试在CPU上运行它而不是GPU。你可以将RenderMode设置为SoftwareOnly(上面链接的列表中的第6项)

Answer 2

我向WPF团队提出了这个问题，总的来说，他们说他们认为动画的平滑度有一些可以改进的小故障。

他们还添加了:

我们非常努力地安排我们的场景更新同步与VBlank获得非常规律，可靠的动画。任何UI线程上的工作可能会受到干扰艰难。在这个例子中，它们是使用DispatcherTimers进行调度在UI线程上创建new故事板，删除旧元素等

他们还演示了一个纯声明式的动画版本，我觉得它看起来更流畅。特别感谢Dwayne Need提供的信息。

Answer 3

这有撕裂的原因是很多对象必须是UI线程拥有的创建和所有这些调用加上将它们添加到UI容器是通过主线程。

我甚至尝试做一个线程驱动的版本，而不是定时器，但这并没有改变任何东西，因为所有的FrameWorkElement对象必须用Dispatcher.Invoke创建。

storyboard和beginStoryboard + EventTrigger的创建都必须在Ui线程上完成。这就是阻碍流畅性的原因。

不幸的是，这种设计没有办法实现无闪烁操作:/

using System;
using System.Linq;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Media.Animation;
using System.Windows.Threading;
using System.Collections.Generic;
namespace SimpleWindow
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow
    {
        readonly SolidColorBrush _fillBrush = new SolidColorBrush(Colors.CadetBlue);
        // Timers
        //private DispatcherTimer _addItemsTimer;
        //private DispatcherTimer _removeItemsTimer;
        private Thread _addItemsTimer;
        private Thread _removeItemsTimer;
        private volatile bool formClosing = false;
        private readonly TimeSpan _addInterval = TimeSpan.FromSeconds(0.21);
        private readonly TimeSpan _removeInterval = TimeSpan.FromSeconds(1);
        public MainWindow()
        {
            InitializeComponent();
            Closing += MainWindow_Closing;
            Loaded += OnLoaded;
        }
        void MainWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            formClosing = true;
            //_addItemsTimer.Join();
            //_removeItemsTimer.Join();
        }
        private void OnLoaded(object o, RoutedEventArgs args)
        {
            _addItemsTimer = new Thread((ThreadStart)delegate() {
                while (!formClosing)
                {
                    Thread.Sleep(_addInterval);
                    AddItems();
                }
            });
            _removeItemsTimer = new Thread((ThreadStart)delegate()
            {
                while (!formClosing)
                {
                    Thread.Sleep(_removeInterval);
                    RemoveOffScreenItems();
                }
            });
            _addItemsTimer.SetApartmentState(ApartmentState.STA);
            _addItemsTimer.Start();
            _removeItemsTimer.SetApartmentState(ApartmentState.STA);
            _removeItemsTimer.Start();
            WindowState = WindowState.Maximized;
        }
        //private static DispatcherTimer CreateTimer(TimeSpan interval, EventHandler handler)
        //{
        //    var timer = new DispatcherTimer();
        //    timer.Interval = interval;
        //    timer.Tick += handler;
        //    timer.Start();
        //    return timer;
        //}
        // Timer callback
        private readonly Rectangle _canvasChildrenLock = new Rectangle();
        public void AddItems()
        {
            lock (_canvasChildrenLock)
            {
                Dispatcher.Invoke((Action)delegate() {
                    var rect = CreateRectangle();
                    rect.Triggers.Add(BeginStoryboardEventTrigger(CreateStoryboard()));
                    MainCanvas.Children.Add(rect); 
                });
            }
        }
        private static EventTrigger BeginStoryboardEventTrigger(Storyboard storyboard)
        {
            var beginStoryboard = new BeginStoryboard {Storyboard = storyboard};
            var eventTrigger = new EventTrigger(LoadedEvent);
            eventTrigger.Actions.Add(beginStoryboard);
            return eventTrigger;
        }
        // Timer callback 
        public void RemoveOffScreenItems()
        {
            lock (_canvasChildrenLock)
            {
                var itemsToRemove = (List<FrameworkElement>)Dispatcher.Invoke((Func<List<FrameworkElement>>)delegate()
                {
                    return (from FrameworkElement element in MainCanvas.Children
                            let topLeft = new Point((double)element.GetValue(Canvas.LeftProperty), (double)element.GetValue(Canvas.TopProperty))
                            where IsOffScreen(topLeft)
                            select element).ToList();
                });
                if (itemsToRemove == null) return;
                foreach (FrameworkElement element in itemsToRemove)
                {
                    Dispatcher.Invoke((Action)delegate() { MainCanvas.Children.Remove(element); });
                }
            }
        }
        private bool IsOffScreen(Point pt)
        {
            return 
                pt.X > MainCanvas.ActualWidth ||
                pt.Y < 0 || pt.Y > MainCanvas.ActualHeight;
        }
        private Rectangle CreateRectangle()
        {
            var rect = new Rectangle
            {
                Width = 100, 
                Height = 100, 
                Fill = _fillBrush
            };
            return rect;
        }
        private const double OffScreenPosition = 100;
        private const double AnimationDuration = 2;
        private Storyboard CreateStoryboard()
        {
            var xAnimation = CreateDoubleAnimationForTranslation();
            xAnimation.From = -OffScreenPosition;
            xAnimation.To = MainCanvas.ActualWidth + OffScreenPosition;
            Storyboard.SetTargetProperty(xAnimation, new PropertyPath(Canvas.LeftProperty));
            var yAnimation = CreateDoubleAnimationForTranslation();
            yAnimation.From = MainCanvas.ActualHeight * Rand.NextDouble();
            yAnimation.To = MainCanvas.ActualHeight * Rand.NextDouble();
            Storyboard.SetTargetProperty(yAnimation, new PropertyPath(Canvas.TopProperty));
            var storyboard = new Storyboard();
            storyboard.Children.Add(xAnimation);
            storyboard.Children.Add(yAnimation);
            storyboard.Freeze();
            return storyboard;
        }
        private DoubleAnimation CreateDoubleAnimationForTranslation()
        {
            var animation = (DoubleAnimation)Dispatcher.Invoke((Func<DoubleAnimation>)delegate()
            {
                return new DoubleAnimation
                {
                    Duration = TimeSpan.FromSeconds(AnimationDuration),
                    EasingFunction = new ShiftedQuadraticEase() { EasingMode = EasingMode.EaseInOut }
                };
            });
            return animation;
        }
        private static readonly Random Rand = new Random(DateTime.Now.Millisecond);
    }
}