Hi,
i try to bind a Base64 (ImageResourceStream) to an image in XAML but end up everytime in an unhandled exception.
This is my code:
ViewModel:
private ObservableCollection<WebImageSource> _imageSources;
public ObservableCollection<WebImageSource> ImageSources
{
get
{
return _imageSources;
}
set
{
if (_imageSources != value)
{
_imageSources = value;
OnPropertyChanged(nameof(ImageSources));
}
}
}
public GalleryViewModel()
{
Title = "Galery";
_testService = new TestService();
ImageSources = new ObservableCollection<WebImageSource>();
this.OnOpenView += async (o, e) =>
{
ImageSources = new ObservableCollection<WebImageSource>((await _testService.Get()));
};
}
WebImageSource just contains a property named Base64 and some meta data.
This is my View:
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.Views.GalleryPage"
xmlns:c="clr-namespace:MyApp.Converters"
Title="{Binding Title}" >
<ContentPage.Resources>
<ResourceDictionary>
<c:Base64ImageSourceConverter x:Key="ImageConverter" />
</ResourceDictionary>
</ContentPage.Resources>
<StackLayout>
<ListView ItemsSource="{Binding ImageSources}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Image Source="{Binding Base64, Converter={StaticResource ImageConverter}}}" Grid.Row="0"
Grid.RowSpan="3" Grid.Column="0"
HorizontalOptions="Center" HeightRequest="50"
VerticalOptions="Center">
</Image>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage>
At least the converter:
public class Base64ImageSourceConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var base64 = (string)value;
if (base64 == null)
return null;
return ImageSource.FromStream(() =>
{
return new MemoryStream(System.Convert.FromBase64String(base64));
});
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
The converter is entered without problems and returns an ImageSource.
Seems that the exception is thrown on binding the new ObservableCollection to my view...
What i am doing wrong here? Can somebody help, please?
