Working with image streams and files in Silverlight

For security and other reasons, Silverlight offers no direct access to the operating system's file system. Even so, there are still several ways to interact with files, whether they are on disk, in memory, over the web, in databases--virtually any location where images are stored. The following snippets show various ways to load/save images with LEADTOOLS Silverlight.

1. Using the Microsoft Load and Save Dialogs:

   VB

   'Loading 
   Try 
     Dim codecs As RasterCodecs = New RasterCodecs() 
     Dim ofd As OpenFileDialog = New OpenFileDialog() 
     If ofd.ShowDialog() = True Then 
        Dim fileStream As FileStream = ofd.File.OpenRead() 
        Try 
           viewerControl.Image = codecs.Load(fileStream) 
        Finally 
           fileStream.Dispose() 
        End Try 
     End If 
   Catch ex As RasterException 
     ' See if LEADTOOLS could not recognize this image format 
     If ex.Code = RasterExceptionCode.FileFormat Then 
        MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS") 
     Else 
        ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
        MessageBox.Show(String.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
     End If 
   Catch ex As Exception 
     ' Other errors 
     MessageBox.Show(String.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)) 
   End Try 
   'Saving  
   Try 
     Dim codecs As RasterCodecs = New RasterCodecs() 
     Dim sfd As SaveFileDialog = New SaveFileDialog() 
     If sfd.ShowDialog() = True Then 
        Dim stream As Stream = sfd.OpenFile() 
        Try 
           codecs.Save(viewerControl.Image, stream, Leadtools.RasterImageFormat.Jpeg, 0) 
        Finally 
           stream.Dispose() 
        End Try 
     End If 
   Catch ex As RasterException 
     ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
     MessageBox.Show(String.Format("Error saving file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
   Catch ex As Exception 
     ' Other errors 
     MessageBox.Show(String.Format("Error saving file.{0}{1}", Environment.NewLine, ex.Message)) 
   End Try 
                                  
                    
        

   C#

   //Loading 
   try 
   { 
     RasterCodecs codecs = new RasterCodecs(); 
     OpenFileDialog ofd = new OpenFileDialog(); 
     if (ofd.ShowDialog() == true) 
     { 
        using (FileStream fileStream = ofd.File.OpenRead()) 
           viewerControl.Image = codecs.Load(fileStream); 
     } 
   } 
   catch (RasterException ex) 
   { 
     // See if LEADTOOLS could not recognize this image format 
     if (ex.Code == RasterExceptionCode.FileFormat) 
        MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS"); 
     else 
     { 
        // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
        MessageBox.Show(string.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
     } 
   } 
   catch (Exception ex) 
   { 
     // Other errors 
     MessageBox.Show(string.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)); 
   } 
   //Saving 
   try 
   { 
     RasterCodecs codecs = new RasterCodecs(); 
     using (IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication()) 
     using (IsolatedStorageFileStream stream = store.CreateFile("myfile.jpg")) 
        codecs.Save(viewerControl.Image, stream, Leadtools.RasterImageFormat.Jpeg, 0); 
   } 
   catch (RasterException ex) 
   { 
     // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
     MessageBox.Show(string.Format("Error saving file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
   } 
   catch (Exception ex) 
   { 
     // Other errors 
     MessageBox.Show(string.Format("Error saving file.{0}{1}", Environment.NewLine, ex.Message)); 
   } 
                                  
                    
        

2. Using the Silverlight Isolated Storage System:

   VB

   'Loading 
   Try 
     Dim codecs As RasterCodecs = New RasterCodecs() 
     Dim store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication() 
     Dim stream As IsolatedStorageFileStream = store.OpenFile("myfile.jpg", FileMode.Open, FileAccess.Read) 
     Try 
        viewerControl.Image = codecs.Load(stream) 
     Finally 
        store.Dispose() 
        stream.Dispose() 
     End Try 
   Catch ex As RasterException 
     ' See if LEADTOOLS could not recognize this image format 
     If ex.Code = RasterExceptionCode.FileFormat Then 
        MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS") 
     Else 
        ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
        MessageBox.Show(String.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
     End If 
   Catch ex As Exception 
     ' Other errors 
     MessageBox.Show(String.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)) 
   End Try          
   'Saving 
   Try 
     Dim codecs As RasterCodecs = New RasterCodecs() 
     Dim store As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication() 
     Dim stream As IsolatedStorageFileStream = store.CreateFile("myfile.jpg") 
     Try 
        codecs.Save(viewerControl.Image, stream, Leadtools.RasterImageFormat.Jpeg, 0) 
     Finally 
        store.Dispose() 
        stream.Dispose() 
     End Try 
   Catch ex As RasterException 
     ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
     MessageBox.Show(String.Format("Error saving file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
   Catch ex As Exception 
     ' Other errors 
     MessageBox.Show(String.Format("Error saving file.{0}{1}", Environment.NewLine, ex.Message)) 
   End Try 
                                  
                    
        

   C#

   //Loading 
   try 
   { 
     RasterCodecs codecs = new RasterCodecs(); 
     using (IsolatedStorageFile store = IsolatedStorageFile.GetUserStoreForApplication()) 
     using (IsolatedStorageFileStream stream = store.OpenFile("myfile.jpg", FileMode.Open, FileAccess.Read)) 
        viewerControl.Image = codecs.Load(stream); 
   } 
   catch (RasterException ex) 
   { 
     // See if LEADTOOLS could not recognize this image format 
     if (ex.Code == RasterExceptionCode.FileFormat) 
        MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS"); 
     else 
     { 
        // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
        MessageBox.Show(string.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
     } 
   } 
   catch (Exception ex) 
   { 
     // Other errors 
     MessageBox.Show(string.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)); 
   } 
   //Saving  
   try 
   { 
     RasterCodecs codecs = new RasterCodecs(); 
     SaveFileDialog sfd = new SaveFileDialog(); 
     if (sfd.ShowDialog() == true) 
     { 
        using (Stream stream = sfd.OpenFile()) 
           codecs.Save(viewerControl.Image, stream, Leadtools.RasterImageFormat.Jpeg, 0); 
     } 
   } 
   catch (RasterException ex) 
   { 
     // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
     MessageBox.Show(string.Format("Error saving file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
   } 
   catch (Exception ex) 
   { 
     // Other errors 
     MessageBox.Show(string.Format("Error saving file.{0}{1}", Environment.NewLine, ex.Message)); 
   } 
                                  
                    
        

3. Using the WebClient Class to download images:

   VB

   ' You may need a cross domain policy file on the server containing the image in order to use the WebClient Class. 
   Dim fileDownloader As WebClient = New WebClient() 
   AddHandler fileDownloader.OpenReadCompleted, AddressOf fileDownloader_OpenReadCompleted 
   fileDownloader.OpenReadAsync(New Uri("http://demo.leadtools.com/images/cmp/image1.cmp"), Nothing) 
   Private Sub fileDownloader_OpenReadCompleted(ByVal sender As Object, ByVal e As OpenReadCompletedEventArgs) 
     Try 
        Dim codecs As RasterCodecs = New RasterCodecs() 
           viewerControl.Image = codecs.Load(e.Result) 
     Catch ex As RasterException 
        ' See if LEADTOOLS could not recognize this image format 
        If ex.Code = RasterExceptionCode.FileFormat Then 
           MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS") 
        Else 
           ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
           MessageBox.Show(String.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
        End If 
     Catch ex As Exception 
        ' Other errors 
        MessageBox.Show(String.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)) 
     End Try 
   End Sub                 
                                  
                    
        

   C#

   // You may need a cross domain policy file on the server containing the image in order to use the WebClient Class. 
   WebClient fileDownloader = new WebClient(); 
   fileDownloader.OpenReadCompleted += new OpenReadCompletedEventHandler(fileDownloader_OpenReadCompleted); 
   fileDownloader.OpenReadAsync(new Uri("http://demo.leadtools.com/images/cmp/image1.cmp"), null); 
   void fileDownloader_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e) 
   { 
     try 
     { 
        RasterCodecs codecs = new RasterCodecs(); 
        viewerControl.Image = codecs.Load(e.Result); 
     } 
     catch (RasterException ex) 
     { 
        // See if LEADTOOLS could not recognize this image format 
        if (ex.Code == RasterExceptionCode.FileFormat) 
           MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS"); 
        else 
        { 
           // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
           MessageBox.Show(string.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
        } 
     } 
     catch (Exception ex) 
     { 
        // Other errors 
        MessageBox.Show(string.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)); 
     } 
   } 
                                  
                    
        

4. Using a WCF or standard web service:

   VB

   'This is the completed event when calling the LEADTOOLS RasterService WCF Service.  
   'LEADTOOLS WCF Services can be used for loading files that the Silverlight library  
   'does not support, for writing barcodes, and much more. Please see Loading And Displaying An Image Using WCF In Silverlight for the complete tutorial. 
   Private Sub client_ConvertCompleted(ByVal sender As Object, ByVal e As ConvertCompletedEventArgs) 
     Try 
        If TypeOf e.Result Is ConvertResponse Then 
           Dim convertResponse As ConvertResponse = CType(IIf(TypeOf e.Result Is ConvertResponse, e.Result, Nothing), ConvertResponse) 
           'Image has been sent back from the service. 
           'Load the image into the viewer. 
           If TypeOf convertResponse.Destination Is RawBinaryData Then 
              Dim ms As MemoryStream = New MemoryStream((CType(IIf(TypeOf convertResponse.Destination Is RawBinaryData, convertResponse.Destination, Nothing), RawBinaryData)).Data) 
              Try 
                  viewerControl.Image = codecs.Load(ms) 
              Finally 
                 ms.Dispose() 
              End Try 
           End If 
        End If 
     Catch ex As RasterException 
        ' See if LEADTOOLS could not recognize this image format 
        If ex.Code = RasterExceptionCode.FileFormat Then 
           MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS") 
        Else 
           ' Other LEADTOOLS error (file might be corrupted, read error, etc.) 
           MessageBox.Show(String.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)) 
        End If 
     Catch ex As Exception 
        ' Other errors 
        MessageBox.Show(String.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)) 
     End Try 
   End Sub            
                                  
                    
        

   C#

   //This is the completed event when calling the LEADTOOLS RasterService WCF Service.  
   //LEADTOOLS WCF Services can be used for loading files that the Silverlight library  
   //does not support, for writing barcodes, and much more. Please see Loading And Displaying An Image Using WCF In Silverlight for the complete tutorial. 
   void client_ConvertCompleted(object sender, ConvertCompletedEventArgs e) 
   { 
     try 
     { 
        if (e.Result is ConvertResponse) 
        { 
           ConvertResponse convertResponse = e.Result as ConvertResponse; 
           //Image has been sent back from the service. 
           //Load the image into the viewer. 
           if (convertResponse.Destination is RawBinaryData) 
           { 
              using (MemoryStream ms = new MemoryStream((convertResponse.Destination as RawBinaryData).Data)) 
                 viewerControl.Image = codecs.Load(ms); 
           } 
        } 
     } 
     catch (RasterException ex) 
     { 
        // See if LEADTOOLS could not recognize this image format 
        if (ex.Code == RasterExceptionCode.FileFormat) 
           MessageBox.Show("File does not contain an image format recognizable by LEADTOOLS"); 
        else 
        { 
           // Other LEADTOOLS error (file might be corrupted, read error, etc.) 
           MessageBox.Show(string.Format("Error loading file.{0}Leadtools code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message)); 
        } 
     } 
     catch (Exception ex) 
     { 
        // Other errors 
        MessageBox.Show(string.Format("Error loading file.{0}{1}", Environment.NewLine, ex.Message)); 
     } 
   }