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)); 
      } 
    } 
                                   
                     
         

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