Question

我在WPF动画中出现撕裂和闪烁问题。我有一个玩具应用程序来演示这些问题。该应用程序在屏幕上设置了正方形动画。方块的边缘显示撕裂，整个动画感觉不平滑。

穿孔器显示> 60fps，~10mb视频内存，0 IRT。

我在两台新的高端计算机上尝试了这一点，并且都显示了相同的不良动画（＆gt; 1gb vram，quad core等）。

SimpleWindow.zip

Answer 1

您是否完全确定您的代码正在运行硬件加速？请查看此列表：http://blogs.msdn.com/b/jgoldb/archive/2010/06/22/software-rendering-usage-in-wpf.aspx。

如果是这样 - 假设你得到了ubercool硬件 - 你可以尝试在CPU而不是GPU上运行它。您可以通过将RenderMode设置为SoftwareOnly（链接到上面的列表中的第6项）来强制执行此操作

Answer 2

我向WPF团队提出了这个问题，总而言之，他们说他们认为动画平滑性有一些可以改进的故障。

他们还补充道：

我们非常努力地安排我们的场景获得与VBlank同步的更新非常规律，可靠的动画。任何 UI线程上的工作可能会干扰强硬。在这个例子中，他们是使用调度的DispatcherTimers 在UI线程上工作以创建新的故事板，删除旧元素等。

他们还展示了动画的纯粹声明版本，对我来说它看起来更顺畅。特别感谢Dwayne Need提供此信息。

Answer 3

这种撕裂的原因是必须创建UI线程的很多对象，并且所有这些调用以及将它们添加到UI容器都是通过主线程。

我甚至尝试使用Thread驱动版本而不是Timers，但这并没有改变任何东西，因为必须使用Dispatcher.Invoke创建所有FrameWorkElement对象。

故事板和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，这种设计无法实现无闪烁操作：/

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);
    }
}

WPF动画有撕裂和闪烁

3 个答案: