未在image.source中显示以使用转换器

Question

I have an Image that is bound as follows:

<Image x:Name="ImgFoto" Source="{Binding Path=Foto, 
                      Converter={StaticResource imageConverter}, Mode=TwoWay, 
                      UpdateSourceTrigger=PropertyChanged}" Stretch="Fill" 
                      HorizontalAlignment="Left" 
                      Height="148" Margin="25,23,0,0" VerticalAlignment="Top" 
                      Width="193"/>"

"Foto" is a SQL field of type Image

My converter class:

public sealed class ImageConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        try
        {
            return new BitmapImage(new Uri((string)value));
        }
        catch
        {
            return new BitmapImage();
        }
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

My problem is that when you run the application the image appears blank.

Answer 1

SQL Image type is in binary so you have to convert binary to bitmapimage instead of uri soirce. try below converter for that

public sealed class ImageConverter : IValueConverter
{
    public object Convert(object value, Type targetType,
                          object parameter, CultureInfo culture)
    {
        if (value == null || value.Length == 0) return null;
       var image = new BitmapImage();
       using (var mem = new MemoryStream((byte[])value))
       {
           mem.Position = 0;
           image.BeginInit();
           image.CreateOptions = BitmapCreateOptions.PreservePixelFormat;
           image.CacheOption = BitmapCacheOption.OnLoad;
           image.UriSource = null;
           image.StreamSource = mem;
           image.EndInit();
       }
       image.Freeze();
       return image;
    }

    public object ConvertBack(object value, Type targetType,
                              object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Answer 2

"Foto" is a SQL field of type Image

If it is a field of type image, then it is stored in Binary format and in the converter, you are converting it to string. This will never work because it is in Binary format. You need to get the bytes and convert it into Bitmap and then return it.

Also if you don't intend to change the image, please make it OneWay binding.

Answer 3

My new XAML is:

            <Image x:Name="ImgFoto" Source="{Binding Foto}"  Stretch="Fill" HorizontalAlignment="Left" 
                       Height="148" Margin="25,23,0,0" VerticalAlignment="Top" Width="193"/>

My code for Charge Image:

  private void BtnCargarFoto_Click(object sender, RoutedEventArgs e)
    {
        OpenFileDialog OD = new OpenFileDialog();
        OD.Filter = "jpg(*.jpg)|*.jpg|png(*.png)|*.png|gif(*.gif)|*.gif|bmp(*.bmp)|*.bmp|All Files(*.*)|*.*";
        if (OD.ShowDialog() == true)
        {
            using (Stream stream = OD.OpenFile())
            {
                bitCoder = BitmapDecoder.Create(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
                ImgFoto.Source = bitCoder.Frames[0];
            }
            System.IO.FileStream fs = new System.IO.FileStream(OD.FileName, System.IO.FileMode.Open);
            foto = new byte[Convert.ToInt32(fs.Length.ToString())];
            fs.Read(foto, 0, foto.Length);
        }
    }

The problem:

The binding is excellent. The problem now is that when charge an image on a record, the same image appears in all other records. After loading and saving the image as you review the records through a Listview, the Image.Source is the same for everyone. I have to exit and reenter the application for the Image.Source to refresh properly. Thanks a lot.