WPF 如何显示gif

刘焱
2023-12-01

最近碰到了要显示表情的需求,而表情刚好是gif的图片。

于是用了Image试了下,发现不行,只会显示第一帧,然后上网查了下资料,大致有这么几种方法,都可以实现。

第一种:

使用Winfrom里面的picturebox,缺点是要引用几个winfrom的dll

 

第二种:

用wpf的mediaelement控件,这控件本身是用来显示视频的,但是可以拿来放gif,

这种方式有一个局限就是图片路径必须是绝对路径

 <MediaElement Source="file://C:\129.gif" />

并且你还需要设置让他循环播放

<MediaElement Source="file://C:\129.gif" MediaEnded="MediaElement_MediaEnded"/>

  private void MediaElement_MediaEnded(object sender, RoutedEventArgs e)
  {
      ((MediaElement)sender).Position=((MediaElement)sender).Position.Add(TimeSpan.FromMilliseconds(1));
  }

而且我发现这种方法在win7以上的系统中才能使用,在XP系统下就失效了,所以果断放弃

 

 


第三种:

大致的思路是:使用GifBitmapDecoder类,其可以将动态GIF分解成很多帧并保存在一个列表中,每一帧为一个BitmapFrame类型的对象,其父类为BitmapSource,可以将每一帧赋值给一个Image控件的Source属性,这样可以得到针对GIF各帧的Image系列。

 

第四种:就是目前我在用的方法,重写下Wpf的Image控件

首先新建一个类继承自Image

 

public class GifImage : System.Windows.Controls.Image
{
/// <summary>
/// gif动画的System.Drawing.Bitmap
/// </summary>
private Bitmap gifBitmap;

/// <summary>
/// 用于显示每一帧的BitmapSource
/// </summary>
private BitmapSource bitmapSource;

public GifImage(string gifPath)
{
this.gifBitmap = new Bitmap(gifPath);
this.bitmapSource = this.GetBitmapSource();
this.Source = this.bitmapSource;
}

/// <summary>
/// 从System.Drawing.Bitmap中获得用于显示的那一帧图像的BitmapSource
/// </summary>
/// <returns></returns>
private BitmapSource GetBitmapSource()
{
IntPtr handle = IntPtr.Zero;

try
{
handle = this.gifBitmap.GetHbitmap();
this.bitmapSource = Imaging.CreateBitmapSourceFromHBitmap(handle, IntPtr.Zero, System.Windows.Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
}
finally
{
if (handle != IntPtr.Zero)
{
DeleteObject(handle);
}
}
return this.bitmapSource;
}

/// <summary>
/// Start animation
/// </summary>
public void StartAnimate()
{
ImageAnimator.Animate(this.gifBitmap, this.OnFrameChanged);
}

/// <summary>
/// Stop animation
/// </summary>
public void StopAnimate()
{
ImageAnimator.StopAnimate(this.gifBitmap, this.OnFrameChanged);
}

/// <summary>
/// Event handler for the frame changed
/// </summary>
private void OnFrameChanged(object sender, EventArgs e)
{
Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action(() =>
{
ImageAnimator.UpdateFrames(); // 更新到下一帧
if (this.bitmapSource != null)
{
this.bitmapSource.Freeze();
}

 Convert the bitmap to BitmapSource that can be display in WPF Visual Tree
this.bitmapSource = this.GetBitmapSource();
Source = this.bitmapSource;
this.InvalidateVisual();
}));
}

/// <summary>
/// Delete local bitmap resource
/// Reference: http://msdn.microsoft.com/en-us/library/dd183539(VS.85).aspx
/// </summary>
[DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool DeleteObject(IntPtr hObject);
} 

然后调用方式如下:

 private GifImage gifImage;
        public MainWindow()
        {
            InitializeComponent();
            this.gifImage = new GifImage("ProgressIndicator.gif");
            this.gifImage.Width = 100;
            this.gifImage.Height = 100;
            this.Content = this.gifImage;
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            Popup dd = new Popup();
            this.gifImage.StartAnimate();
        }

经测试,可以在xp下完美显示

 

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