GetDownloadStreamAsync Method (original) (raw)
Summary
Obtains a stream asynchronously that can be used to download an item in SharePoint server.
Syntax
Parameters
sourceUri
The full URI for the source item in the SharePoint server. This value cannot be null (Nothing in VB). It must be the URI to a valid SharePoint item, for example http://server/Shared Documents/File.ext.
userState
The optional user-supplied state object that is used to identify the task that raised the DownloadCompleted event.
Example
This example will get the stream for a document asynchronously at the specified SharePoint and then get the image information using Leadtools.Codecs.RasterCodecs.
using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing;
using Leadtools.ImageProcessing.Color;
using Leadtools.SharePoint.Client;
public void SharePointClientDownloadStreamAsyncExample()
{
// Replace SHAREPOINT_SITE_URI with a valid URL to a SharePoint site, for example
// http://SiteCollection/MySite
Uri siteUri = new Uri(SHAREPOINT_SITE_URI);
// Replace SHAREPOINT_FOLDER_NAME with a valid folder on the site above, for example
// "Documents" or "Documents\Sub Documents"
string folderName = SHAREPOINT_FOLDER_NAME;
// Replace SHAREPOINT_DOCUMENT_NAME with a valid document on the folder above, for example
// MyDocument.tif
string documentName = SHAREPOINT_DOCUMENT_NAME;
// Build the full URL to the document are we going to download
UriBuilder builder = new UriBuilder(siteUri);
builder.Path = Path.Combine(builder.Path, folderName);
builder.Path = Path.Combine(builder.Path, documentName);
Uri sourceDocumentUri = builder.Uri;
SharePointClient spClient = new SharePointClient();
// Optional: Set the credentials:
spClient.Credentials = new NetworkCredential(USER_NAME, PASSWORD, DOMAIN);
// If this is a console application demo, we might exit the program before the operation completes,
// so use a wait handle to not exit this method till the opreation completes
AutoResetEvent wait = new AutoResetEvent(false);
// Download the SharePoint item to the temporary file asynchronously
spClient.DownloadCompleted += new EventHandler<SharePointClientDownloadCompletedEventArgs>(MyDownloadStreamAsyncCompleted);
spClient.GetDownloadStreamAsync(sourceDocumentUri, wait);
// Wait till the operation completes
wait.WaitOne();
wait.Close();
}
private static void MyDownloadStreamAsyncCompleted(object sender, SharePointClientDownloadCompletedEventArgs e)
{
// Remove our handler
SharePointClient spClient = sender as SharePointClient;
spClient.DownloadCompleted -= new EventHandler<SharePointClientDownloadCompletedEventArgs>(MyDownloadStreamAsyncCompleted);
if (e.Error == null && !e.Cancelled)
{
// All is OK, use RasterCodecs to get its info
using (RasterCodecs codecs = new RasterCodecs())
{
using (CodecsImageInfo imageInfo = codecs.GetInformation(e.DestinationData.Stream, true))
{
// Show the image info
Console.WriteLine("URL: {0}", e.SourceUri);
Console.WriteLine("Pages: {0}", imageInfo.TotalPages);
Console.WriteLine("Size: {0} by {1} pixels", imageInfo.Width, imageInfo.Height);
Console.WriteLine("Resolution: {0} by {1} dpi", imageInfo.XResolution, imageInfo.YResolution);
Console.WriteLine("Bits/Pixel: {0}", imageInfo.BitsPerPixel);
}
}
}
else
{
// Some error occured
if (e.Error != null)
Console.WriteLine(e.Error.Message);
else
Console.WriteLine("User cancelled");
}
// Dispose the SharePoint stream
if (e.DestinationData != null)
{
e.DestinationData.Dispose();
}
// Tell whoever is listening that we are done
EventWaitHandle wait = e.UserState as EventWaitHandle;
wait.Set();
}