WPF 图像 UriSource 和使用 http:\ URL 的数据绑定 [英] WPF Image UriSource and Data Binding using http:\ URL
问题描述
我在 WPF 用户控件中显示带有 Web URL 的图像时遇到问题.我已经完成了 2008 年 8 月在本网站上提出的类似问题的所有建议(ImageUriSource 和数据绑定)，但这些建议都没有奏效.
I am having a problem displaying an image with a web URL in a WPF user control. I have worked through all the suggestions for a similar problem asked on this site in Aug 2008 (Image UriSource and Data Binding) but none of those suggestions have worked.
我想做的是:
<Image Width="50" Name="MemberImage">
<Image.Source>
<BitmapImage DecodePixelWidth="50" UriSource="{Binding Member.ImageFilePathUri}" />
</Image.Source>
</Image>
ImageFilePathUri 是从字符串路径创建的 Uri:
ImageFilePathUri is a Uri created from the string path through:
public Uri ImageFilePathUri
{
get
{
return new Uri(this.ImageFilePath);
}
}
}
这给出了必须设置属性 'UriSource' 或属性 'StreamSource'."错误如预期.
This gives the "Property 'UriSource' or property 'StreamSource' must be set." error as expected.
我也尝试过使用值转换器:
I have also tried using a value converter:
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，绑定到它使用:
<Image Name="TestImage" Width="50" Source="{Binding Path=Member.ImageFilePath, Converter=Parliament.HansardApplicationSuite.Logging.Helpers.ImageConverter}"></Image>
不显示图像.
进一步尝试以编程方式加载图像，在控件构造函数和/或控件 Loaded 事件中也没有奏效:
A further attempt to load the image programmatically, in the control constructor and/or the control Loaded event have also not worked:
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;
}
有效的一件事是将图像保存到本地文件路径并显示:
The one thing that has worked is saving the image to a local file path and displaying that:
<Image Width="50" Name="MemberImage">
<Image.Source>
<BitmapImage DecodePixelWidth="50" UriSource="C:Data6bc64e7b-2df5-40d5-b6c4-eaf732318222.jpg" />
</Image.Source>
</Image>
这显然只在调试问题时有用，而不是解决方案.相同的代码，但用 http 地址代替本地文件路径不起作用.
This is obviously only useful in debugging the problem and is not a solution. The same code but substituting the http address for the local file path doesn't work.
<Image.Source>
<BitmapImage DecodePixelWidth="50" UriSource="http://member.org/6bc64e7b-2df5-40d5-b6c4-eaf732318222.jpg" />
</Image.Source>
更新:
这是 MemberImage 属性的实现.
This is the MemberImage property implementation.
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:
这就是我在视图中绑定到控件的方式:
This is how I am binding to the control in my view:
<Image Width="50" Source="{Binding MemberImage}" />
MemberImage 是我在上面给出的属性.我的数据上下文设置正确，因为该属性正在运行，只是没有返回图像.
MemberImage is the property I have given above. My data context is being set correctly because that property is being run, it's just not returning an image.
推荐答案
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图像并将该路径绑定到 UriSource.见下文
WebURL can't be provided as a source to UriSource property of BitmapImage. If it is weburl you need to download that image locally and bind that path to UriSource. See the below
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;
}
这篇关于WPF 图像 UriSource 和使用 http:\ URL 的数据绑定的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
