让WPF图像加载异步 [英] Make WPF Image load async

问题描述

我想加载的gravatar的图像和code设置他们背后一个WPF图像控制。
因此，code看起来像

I would like to load Gravatar-Images and set them from code behind to a WPF Image-Control. So the code looks like

imgGravatar.Source = GetGravatarImage(email);

在哪里GetGravatarImage如下：

Where GetGravatarImage looks like:

BitmapImage bi = new BitmapImage();
bi.BeginInit();
bi.UriSource = new Uri( GravatarImage.GetURL( "http://www.gravatar.com/avatar.php?gravatar_id=" + email) , UriKind.Absolute );
bi.EndInit();
return bi;

不幸的是，当网络连接速度慢这一锁定GUI。是否有指定图像源，让它在后台加载图像，而不阻塞UI的方式？

Unfortunately this locks the GUI when the network connection is slow. Is there a way to assign the image-source and let it load the image in the background without blocking the UI?

谢谢！

推荐答案

我建议你使用你的imgGravatar从XAML绑定。将 IsAsync = TRUE 它和WPF会自动使用来自线程池中的线程来拉你的形象。你可以封装解决逻辑成的IValueConverter，只是绑定的电子邮件源

I suggest you to use a Binding on your imgGravatar from XAML. Set IsAsync=true on it and WPF will automatically utilize a thread from the thread pool to pull your image. You could encapsulate the resolving logic into an IValueConverter and simply bind the email as Source

在XAML：

<Window.Resouces>
    <local:ImgConverter x:Key="imgConverter" />
</Window.Resource>

...


<Image x:Name="imgGravatar" 
       Source="{Binding Path=Email, 
                        Converter={StaticResource imgConverter}, 
                        IsAsync=true}" />

在code：

public class ImgConverter : IValueConverter
{
    public override object Convert(object value, ...)
    {
        if (value != null)
        {
             BitmapImage bi = new BitmapImage();
             bi.BeginInit();
             bi.UriSource = new Uri( 
                 GravatarImage.GetURL(
                     "http://www.gravatar.com/avatar.php?gravatar_id=" + 
                      value.ToString()) , UriKind.Absolute 
                 );
             bi.EndInit();
             return bi;                
        }
        else
        {
            return null;
        }

    }
}

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