Overloads Public Function GetInformationAsync( _
   ByVal uri As Uri, _
   ByVal totalPages As Boolean, _
   ByVal pageNumber As Integer, _
   ByVal userState As Object _
) As CodecsImageInfo

Visual Basic (Usage)	Copy Code
Dim instance As RasterCodecs Dim uri As Uri Dim totalPages As Boolean Dim pageNumber As Integer Dim userState As Object Dim value As CodecsImageInfo   value = instance.GetInformationAsync(uri, totalPages, pageNumber, userState)

public CodecsImageInfo GetInformationAsync( 
   Uri uri,
   bool totalPages,
   int pageNumber,
   object userState
)

public:
CodecsImageInfo^ GetInformationAsync( 
   Uri^ uri,
   bool totalPages,
   int pageNumber,
   Object^ userState
) 

Parameters

uri

The System.Uri containing the input image data.

totalPages

true to query the URI for total number of pages, false otherwise.

pageNumber

The page number to query. Pass 1 for the first page (default).

userState

A user-defined object that is passed to the method invoked when the asynchronous operation completes.

Return Value

Specifying true for totalPages can cause the process to be slow for files with large number of pages.

LEADTOOLS supports the following URI schemes:

If uri points to a resource in a System.Uri.UriSchemeHttp, System.Uri.UriSchemeHttps or System.Uri.UriSchemeFtp, then this RasterCodecs will attempt to download image data in an iterative fashion by creating a temporary buffer. The size of this buffer can be determined and changed by setting up the UriOperationBufferSize prior to calling this method.

For authentical and proxy settings, refer to UriOperationCredentials and UriOperationProxy.

The RasterCodecs class supports getting information on image files asynchronously using the GetInformationAsync methods. When calling any of these methods, the caller thread will not be blocked and the method will return instantly with an instance CodecsImageInfo that is in a loading status (CodecsImageInfo.IsLoading set to true). You should not use the other properties of this object while the object is in loading status.

When the RasterCodecs object finishes getting the information on the file, the various properties of the CodecsImageInfo will be populated with the image file information and the CodecsImageInfo.IsLoading property will be set to false.

It is recommended that you do not poll for the CodecsImageInfo.IsLoading property to check when the image information has been collected, instead, subscribe to the GetInformationAsyncCompleted event to get notification on when the RasterCodecs.GetInformationAsync operation is completed and if any errors occurred.

The GetInformationAsyncCompleted event data will also contain the same object returned from GetInformationAsync so you do not have to keep the original object in your application.

userState will be passed to the CodecsGetInformationAsyncCompletedEventArgs.UserState member of the GetInformationAsyncCompleted event data.

Target Platforms: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only)

Reference