添加到主响应，建议使用WpfAnimatedGif，你必须在最后添加以下行，如果你是交换图像与Gif，以确保动画实际执行:

ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

所以你的代码看起来像这样:

var image = new BitmapImage();
image.BeginInit();
image.UriSource = new Uri(fileName);
image.EndInit();
ImageBehavior.SetAnimatedSource(img, image);
ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

GifImage.Initialize()方法的小改进，该方法从GIF元数据中读取适当的帧定时。

    private void Initialize()
    {
        _gifDecoder = new GifBitmapDecoder(new Uri("pack://application:,,," + this.GifSource), BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);

        int duration=0;
        _animation = new Int32AnimationUsingKeyFrames();
        _animation.KeyFrames.Add(new DiscreteInt32KeyFrame(0, KeyTime.FromTimeSpan(new TimeSpan(0))));
        foreach (BitmapFrame frame in _gifDecoder.Frames)
        {
            BitmapMetadata btmd = (BitmapMetadata)frame.Metadata;
            duration += (ushort)btmd.GetQuery("/grctlext/Delay");
            _animation.KeyFrames.Add(new DiscreteInt32KeyFrame(_gifDecoder.Frames.IndexOf(frame)+1, KeyTime.FromTimeSpan(new TimeSpan(duration*100000))));
        }            
         _animation.RepeatBehavior = RepeatBehavior.Forever;
        this.Source = _gifDecoder.Frames[0];            
        _isInitialized = true;
    }

我无法让这个问题最流行的答案(上面由达里奥提出)正常工作。结果是奇怪的、起伏不定的动画和奇怪的工件。 目前为止我找到的最佳解决方案: https://github.com/XamlAnimatedGif/WpfAnimatedGif

你可以用NuGet安装它

WpfAnimatedGif安装包

并使用它，在一个新的名称空间的窗口，你想添加gif图像，并使用它如下所示

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:gif="http://wpfanimatedgif.codeplex.com" <!-- THIS NAMESPACE -->
    Title="MainWindow" Height="350" Width="525">

<Grid>
    <!-- EXAMPLE USAGE BELOW -->
    <Image gif:ImageBehavior.AnimatedSource="Images/animated.gif" />

这个包非常简洁，你可以像下面这样设置一些属性

<Image gif:ImageBehavior.RepeatBehavior="3x"
       gif:ImageBehavior.AnimatedSource="Images/animated.gif" />

你也可以在你的代码中使用它:

var image = new BitmapImage();
image.BeginInit();
image.UriSource = new Uri(fileName);
image.EndInit();
ImageBehavior.SetAnimatedSource(img, image);

编辑:Silverlight支持

根据josh2112的评论，如果你想在Silverlight项目中添加GIF动画支持，请使用github.com/XamlAnimatedGif/XamlAnimatedGif

我也搜索了一下，在旧MSDN论坛的一个帖子里找到了几个不同的解决方案。(链接不再工作，所以我删除了它)

最简单的执行似乎是使用WinForms PictureBox控件，并像这样(从线程中更改了一些东西，大部分是相同的)。

添加对System.Windows的引用。窗体，WindowsFormsIntegration和系统。首先绘制你的项目。

<Window x:Class="GifExample.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:wfi="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration"
    xmlns:winForms="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
    Loaded="Window_Loaded" >
    <Grid>
        <wfi:WindowsFormsHost>
            <winForms:PictureBox x:Name="pictureBoxLoading">
            </winForms:PictureBox>
        </wfi:WindowsFormsHost>
    </Grid>
</Window >

然后在Window_Loaded处理程序中，你会设置pictureBoxLoading。将ImageLocation属性设置为要显示的图像文件路径。

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    pictureBoxLoading.ImageLocation = "../Images/mygif.gif";
}

在那个线程中提到了MediaElement控件，但也提到了它是一个相当笨重的控件，因此有许多替代方案，包括至少两个基于Image控件的自制控件，因此这是最简单的。

添加到主响应，建议使用WpfAnimatedGif，你必须在最后添加以下行，如果你是交换图像与Gif，以确保动画实际执行:

ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

所以你的代码看起来像这样:

var image = new BitmapImage();
image.BeginInit();
image.UriSource = new Uri(fileName);
image.EndInit();
ImageBehavior.SetAnimatedSource(img, image);
ImageBehavior.SetRepeatBehavior(img, new RepeatBehavior(0));
ImageBehavior.SetRepeatBehavior(img, RepeatBehavior.Forever);

我发布了一个扩展图像控件和使用Gif解码器的解决方案。gif解码器有一个frames属性。我动画FrameIndex属性。事件ChangingFrameIndex将源属性更改为与FrameIndex对应的帧(在解码器中)。我猜这个动图每秒有10帧。

class GifImage : Image
{
    private bool _isInitialized;
    private GifBitmapDecoder _gifDecoder;
    private Int32Animation _animation;

    public int FrameIndex
    {
        get { return (int)GetValue(FrameIndexProperty); }
        set { SetValue(FrameIndexProperty, value); }
    }

    private void Initialize()
    {
        _gifDecoder = new GifBitmapDecoder(new Uri("pack://application:,,," + this.GifSource), BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
        _animation = new Int32Animation(0, _gifDecoder.Frames.Count - 1, new Duration(new TimeSpan(0, 0, 0, _gifDecoder.Frames.Count / 10, (int)((_gifDecoder.Frames.Count / 10.0 - _gifDecoder.Frames.Count / 10) * 1000))));
        _animation.RepeatBehavior = RepeatBehavior.Forever;
        this.Source = _gifDecoder.Frames[0];

        _isInitialized = true;
    }

    static GifImage()
    {
        VisibilityProperty.OverrideMetadata(typeof (GifImage),
            new FrameworkPropertyMetadata(VisibilityPropertyChanged));
    }

    private static void VisibilityPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        if ((Visibility)e.NewValue == Visibility.Visible)
        {
            ((GifImage)sender).StartAnimation();
        }
        else
        {
            ((GifImage)sender).StopAnimation();
        }
    }

    public static readonly DependencyProperty FrameIndexProperty =
        DependencyProperty.Register("FrameIndex", typeof(int), typeof(GifImage), new UIPropertyMetadata(0, new PropertyChangedCallback(ChangingFrameIndex)));

    static void ChangingFrameIndex(DependencyObject obj, DependencyPropertyChangedEventArgs ev)
    {
        var gifImage = obj as GifImage;
        gifImage.Source = gifImage._gifDecoder.Frames[(int)ev.NewValue];
    }

    /// <summary>
    /// Defines whether the animation starts on it's own
    /// </summary>
    public bool AutoStart
    {
        get { return (bool)GetValue(AutoStartProperty); }
        set { SetValue(AutoStartProperty, value); }
    }

    public static readonly DependencyProperty AutoStartProperty =
        DependencyProperty.Register("AutoStart", typeof(bool), typeof(GifImage), new UIPropertyMetadata(false, AutoStartPropertyChanged));

    private static void AutoStartPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        if ((bool)e.NewValue)
            (sender as GifImage).StartAnimation();
    }

    public string GifSource
    {
        get { return (string)GetValue(GifSourceProperty); }
        set { SetValue(GifSourceProperty, value); }
    }

    public static readonly DependencyProperty GifSourceProperty =
        DependencyProperty.Register("GifSource", typeof(string), typeof(GifImage), new UIPropertyMetadata(string.Empty, GifSourcePropertyChanged));

    private static void GifSourcePropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        (sender as GifImage).Initialize();
    }

    /// <summary>
    /// Starts the animation
    /// </summary>
    public void StartAnimation()
    {
        if (!_isInitialized)
            this.Initialize();

        BeginAnimation(FrameIndexProperty, _animation);
    }

    /// <summary>
    /// Stops the animation
    /// </summary>
    public void StopAnimation()
    {
        BeginAnimation(FrameIndexProperty, null);
    }
}

使用示例(XAML):

<controls:GifImage x:Name="gifImage" Stretch="None" GifSource="/SomeImage.gif" AutoStart="True" />