使用http:\\ URL的WPF图像UriSource和数据绑定

Question

我在WPF用户控件中显示带有Web URL的图像时遇到问题.我已经解决了2008年8月在本网站上提出的类似问题的所有建议(图像UriSource和数据绑定),但这些建议都没有奏效.

我想做的是:

<Image Width="50" Name="MemberImage">
    <Image.Source>
        <BitmapImage DecodePixelWidth="50" UriSource="{Binding Member.ImageFilePathUri}" />
    </Image.Source>
</Image>

ImageFilePathUri是一个从字符串路径创建的Uri:

public Uri ImageFilePathUri
    {
        get
        {
            return new Uri(this.ImageFilePath);
        }
    }
}

这样就必须设置"Property'UriSource'或属性'StreamSource'." 错误如预期.

我也尝试过使用值转换器:

public class ImageConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var image = new BitmapImage();
        image.BeginInit();
        if (value != null)
        {
            image.UriSource = new Uri((string)value);
        }
        image.DecodePixelWidth = 50;
        image.EndInit();
        return image;
    }
}

但是,使用以下方法绑定它:

<Image Name="TestImage" Width="50" Source="{Binding Path=Member.ImageFilePath, Converter=Parliament.HansardApplicationSuite.Logging.Helpers.ImageConverter}"></Image>

不显示图像.

在控件构造函数和/或控件Loaded事件中以编程方式加载图像的进一步尝试也没有起作用:

if (this.MemberRollItemViewModel.Member != null)
{
    var image = new BitmapImage();
    image.BeginInit();
    image.UriSource = new Uri(this.MemberRollItemViewModel.Member.ImageFilePath);
    image.DecodePixelWidth = 50;
    image.EndInit();

    this.MemberImage.Source = image;
}

有一件事是将图像保存到本地文件路径并显示:

<Image Width="50" Name="MemberImage">
    <Image.Source>
        <BitmapImage DecodePixelWidth="50" UriSource="C:\Data\6bc64e7b-2df5-40d5-b6c4-eaf732318222.jpg" />
    </Image.Source>
</Image>

这显然仅在调试问题时有用,而不是解决方案.相同的代码但用http地址替换本地文件路径不起作用.

<Image.Source>
    <BitmapImage DecodePixelWidth="50" UriSource="http://member.org/6bc64e7b-2df5-40d5-b6c4-eaf732318222.jpg" />
</Image.Source>

更新:

这是MemberImage属性实现.

public BitmapImage MemberImage
{
    get
    {
        var image = new BitmapImage();

        if (this.Member != null)
        {
            WebRequest request = WebRequest.Create(new Uri(this.Member.ImageFilePath, UriKind.Absolute));
            request.Timeout = -1;
            WebResponse response = request.GetResponse();
            Stream responseStream = response.GetResponseStream();
            BinaryReader reader = new BinaryReader(responseStream);
            MemoryStream memoryStream = new MemoryStream();

            byte[] bytebuffer = new byte[BytesToRead];
            int bytesRead = reader.Read(bytebuffer, 0, BytesToRead);

            while (bytesRead > 0)
            {
                memoryStream.Write(bytebuffer, 0, bytesRead);
                bytesRead = reader.Read(bytebuffer, 0, BytesToRead);
            }

            image.BeginInit();
            memoryStream.Seek(0, SeekOrigin.Begin);

            image.StreamSource = memoryStream;
            image.EndInit();
        }

        return image;
    }
}

更新:

这是我在视图中绑定到控件的方式:

<Image Width="50" Source="{Binding MemberImage}" />

MemberImage是我上面给出的属性.正在设置我的数据上下文,因为该属性正在运行,它只是没有返回图像.

Answer 1

WebURL不能作为BitmapImage的UriSource属性的源提供.如果是weburl,则需要在本地下载该映像并将该路径绑定到UriSource.见下文

http://blogs.windowsclient.net/cennest/archive/2010/03/26/code-for-keeps-wpf-silverlight-retrieve-images-from-db-url.aspx

更新:

void MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        var image = new BitmapImage();
        int BytesToRead=100;

        WebRequest request = WebRequest.Create(new Uri("http://www.interweb.in/attachments/pc-wallpapers/16187d1222942178-nature-wallpaper-nature-summer-wallpaper.jpg", UriKind.Absolute));
        request.Timeout = -1;
        WebResponse response = request.GetResponse();
        Stream responseStream = response.GetResponseStream();
        BinaryReader reader = new BinaryReader(responseStream);
        MemoryStream memoryStream = new MemoryStream();

        byte[] bytebuffer = new byte[BytesToRead];
        int bytesRead = reader.Read(bytebuffer, 0, BytesToRead);

        while (bytesRead > 0)
        {
            memoryStream.Write(bytebuffer, 0, bytesRead);
            bytesRead = reader.Read(bytebuffer, 0, BytesToRead);
        }

        image.BeginInit();
        memoryStream.Seek(0, SeekOrigin.Begin);

        image.StreamSource = memoryStream;
        image.EndInit();

        myImage.Source = image;
    }