Question

The way I try implement it via standart Windows.Forms (to get valide DialogResult.OK)

            System.Windows.Forms.SaveFileDialog dlg = new System.Windows.Forms.SaveFileDialog();
            dlg.FileName = "Document"; // Default file name
           // dlg.DefaultExt = ".jpg"; // Default file extension
            dlg.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif";
            if(dlg.ShowDialog()== System.Windows.Forms.DialogResult.OK) 
if (dlg.DialogResult.HasValue && splashDialog.DialogResult.Value)
            {
              string fName = dlg.FileName; 
              if (dlg.FileName != "")
              {
                 System.IO.Stream fileStream = (System.IO.FileStream)dlg.OpenFile(); 

                  fileStream.Close();
               }
             }

This is using Windows forms but it saves blank image((

Answer 1

You can do something like that:

var encoder = new JpegBitmapEncoder(); // Or PngBitmapEncoder, or whichever encoder you want
encoder.Frames.Add(BitmapFrame.Create(yourImage));
using (var stream = dlg.OpenFile())
{
    encoder.Save(stream);
}

BTW, there is a SaveFileDialog in WPF too, you don’t have to use the one from Windows Forms