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LoadAsync(string,object) Method

Summary

Loads the specified image file using default options asynchronously.

Syntax

Objective-C

WinRT C#

C++

public RasterImage LoadAsync( 
   string fileName, 
   object userState 
)

Public Overloads Function LoadAsync( _ 
   ByVal fileName As String, _ 
   ByVal userState As Object _ 
) As Leadtools.RasterImage

public Leadtools.RasterImage LoadAsync(  
   string fileName, 
   object userState 
)

- (void)loadFileAsync:(NSString *)file  
           completion:(void (^)(LTRasterImage * nullable image, NSError * nullable error))completion

 function Leadtools.Codecs.RasterCodecs.LoadAsync(String,Object)(  
   fileName , 
   userState  
)

public: 
Leadtools.RasterImage^ LoadAsync(  
   String^ fileName, 
   Object^ userState 
)

Parameters

fileName
A String containing the name of the image file to load.

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

Return Value

The RasterImage object that this method loads. See remarks for the usage of this object.

Remarks

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

This method will load all the pages in a multi-page 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.

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 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 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 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.

The CodecsLoadOptions.AllPages property controls whether RasterCodecs will try to load all pages or just the first page if the image data contains multiple pages. To load a single page, use LoadAsync(string fileName, int pageNumber, object userState).

Example

Requirements

Target Platforms