我一直在浏览不同的帖子,试图弄清楚我的问题有什么问题。基本上我的用户控件上有一个Image标签,而我想要绑定到一个url。但是这不起作用。我尝试使用返回BitmapImage(new Uri((string)value));
的ValueConverter
但这不起作用。我唯一能得到的是你不能绑定到一个url,你必须下载你想要绑定的图像。我不想下载我seacrch的所有图像。是否需要在本地下载图像来完成此任务。我认为通过返回BitmapImage,ValueConverter方法将是最好的。请帮帮忙?
public class MyViewModel
{
private string _posterUrl;
public string PosterUrl
{
get
{
//Get Image Url, this is an example and will be retrieved from somewhere else.
_posterUrl = "http://www.eurobuzz.org/wp-content/uploads/2012/08/logo.jpg";
return _posterUrl;
}
set
{
_posterUrl = value;
NofityPropertyChanged(p => p.PosterUrl);
}
}
}
这是我的ValueConverter:
public class BitmapImageConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if(value is string)
return new BitmapImage(new Uri((string)value, UriKind.RelativeOrAbsolute));
if(value is Uri)
return new BitmapImage((Uri)value);
throw new NotSupportedException();
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
这是我的XAML:
<Image Source="{Binding PosterUrl, Converter={StaticResource bitmapImageConverter}}" Width="100" Height="100" />
因此,它绑定到包含imageurl的PosterUrl属性,并将其转换为bitmapimage。有什么想法吗?
答案 0 :(得分:1)
试试吧
<Image Helpers:ImageAsyncHelper.SourceUri="{Binding Url, IsAsync=True}" x:Name="img" />
其中
using System;
using System.Windows;
using System.Windows.Data;
using System.Windows.Controls;
public class ImageAsyncHelper : DependencyObject {
public static Uri GetSourceUri(DependencyObject obj){
return (Uri)obj.GetValue(SourceUriProperty);
}
public static void SetSourceUri(DependencyObject obj, Uri value){
obj.SetValue(SourceUriProperty, value);
}
public static readonly DependencyProperty SourceUriProperty =
DependencyProperty.RegisterAttached("SourceUri",
typeof(Uri),
typeof(ImageAsyncHelper),
new PropertyMetadata { PropertyChangedCallback = (obj, e) =>
((Image)obj).SetBinding(
Image.SourceProperty,
new Binding("VerifiedUri"){
Source = new ImageAsyncHelper{
_givenUri = (Uri)e.NewValue
},
IsAsync = true
}
)
}
);
private Uri _givenUri;
public Uri VerifiedUri {
get {
try {
System.Net.Dns.GetHostEntry(_givenUri.DnsSafeHost);
return _givenUri;
}
catch (Exception) {
return null;
}
}
}
}
并且
public Uri Url {
get {
return new Uri(SomeString, UriKind.Absolute);
}
}
答案 1 :(得分:0)
你想这样做吗?
<UserControl x:Class="WpfApplication1.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<StackPanel Orientation="Vertical">
<Image Height="100" Width="100" Source="{Binding}" />
<Image Height="100" Width="100" Source="http://www.eurobuzz.org/wp-content/uploads/2012/08/logo.jpg"/>
</StackPanel>
代码背后:
public partial class UserControl1 : UserControl
{
public UserControl1()
{
this.DataContext = "http://www.eurobuzz.org/wp-content/uploads/2012/08/logo.jpg";
InitializeComponent();
}
}