GetInformationAsync(Uri,Boolean,Int32,Object) Method

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

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

'Usage
 
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
)

 function Leadtools.Codecs.RasterCodecs.GetInformationAsync(Uri,Boolean,Int32,Object)( 
   uri ,
   totalPages ,
   pageNumber ,
   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.

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 authenticity 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 about 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 determine whether the image information has been collected. Instead, subscribe to the GetInformationAsyncCompleted event to get notification on when the GetInformationAsync(String,Boolean,Int32,Object) operation is completed and whether 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: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterCodecs Class
RasterCodecs Members
Overload List
Loading and Saving Large Tiff Files
Speeding Up 1-Bit Documents