LoadAsync(Uri,Int32,Object) Method

public RasterImage LoadAsync( 
   Uri uri,
   int pageNumber,
   object userState
)

'Declaration
 
Public Overloads Function LoadAsync( _
   ByVal uri As Uri, _
   ByVal pageNumber As Integer, _
   ByVal userState As Object _
) As RasterImage

'Usage
 
Dim instance As RasterCodecs
Dim uri As Uri
Dim pageNumber As Integer
Dim userState As Object
Dim value As RasterImage
 
value = instance.LoadAsync(uri, pageNumber, userState)

public RasterImage LoadAsync( 
   Uri uri,
   int pageNumber,
   object userState
)

 function Leadtools.Codecs.RasterCodecs.LoadAsync(Uri,Int32,Object)( 
   uri ,
   pageNumber ,
   userState 
)

public:
RasterImage^ LoadAsync( 
   Uri^ uri,
   int pageNumber,
   Object^ userState
) 

Parameters

uri

The System.Uri containing the input image data.

pageNumber

1-based page number to load.

userState

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

Return Value

The file can be in any supported image file format and bits per pixel, whether compressed or uncompressed.

This method will load a single page from a multipage file. The resulting image will have the same bits/pixel and color order value of the image as it was stored in the file.

LEADTOOLS will attempt to load corrupted files so you can see at least a portion of the image. For these images, the load methods succeed, but LoadStatus will return an error code.

Use the CodecsLoadOptions class to set up other load option parameters before calling this method.

Support for 12 and 16-bit grayscale images is only available in the Document/Medical Imaging editions.

For supported formats, refer to Summary of All Supported Image File Formats.

LEADTOOLS loads all PDF files as Raster PDF uncompressed RasterImageFormat.RasPdf, regardless of the compression and color space used when saving the file.

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 loading image files asynchronously using the LoadAsync methods. When calling any of these methods, the caller thread will not be blocked and the method will return instantly with an instance of Leadtools.RasterImage that is in a loading status (RasterImage.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 loading the image, the various properties of the Leadtools.RasterImage will be populated with the image information and data and the RasterImage.IsLoading property will be set to false.

Do not poll the RasterImage.IsLoading property to determine whether the image has finished loading. Instead, subscribe to the LoadAsyncCompleted event to get notification when the LoadAsync(String,LeadRect,Int32,CodecsLoadByteOrder,Int32,Int32,Object) operation has completed and whether any errors occurred.

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

Target Platforms

Reference

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