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CodecsLoadAsyncCompletedEventArgs Class

Summary

Contains data for the RasterCodecs.LoadAsyncCompleted event.

Syntax
C#
VB
C++
Java
public class CodecsLoadAsyncCompletedEventArgs : CodecsAsyncCompletedEventArgs 
Public Class CodecsLoadAsyncCompletedEventArgs  
   Inherits CodecsAsyncCompletedEventArgs 
public class CodecsLoadAsyncCompletedEvent extends CodecsAsyncCompletedEvent 
public ref class CodecsLoadAsyncCompletedEventArgs : public CodecsAsyncCompletedEventArgs  
Remarks

NOTE: This topic is part of RasterCodecs Async support using the .NET System.ComponentMode.AsyncOperation model. For .NET async/await support this type/member is not used. Instead, refer to RasterCodecs Async Operations.

The RasterCodecs class supports loading image files asynchronously using the RasterCodecs.LoadAsync methods. When calling any of these methods, the caller's thread will not be blocked and the method will return instantly with an instance of RasterImage that is in a loading status (theRasterImage.IsLoading property is set to true). Do 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 is finished loaded. Instead, subscribe to the RasterCodecs.LoadAsyncCompleted event to get notification when the LoadAsync operation is completed and whether any errors occurred.

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

The RasterCodecs.LoadAsyncCompleted event uses a data argument object of type CodecsLoadAsyncCompletedEventArgs. This class contains the following properties:

Property Description
Uri, Stream and FileName

Contains the URI, stream or file name passed to the method that initialized this asynchronous operation.

Only one of these properties can be a valid value (not a null reference) at any time The property that contains a valid reference depends on what version of RasterCodecs.LoadAsync method has been called.

For example, if RasterCodecs.LoadAsync(Uri uri, object userState) is being called, the Uri will contain the same URI passed to the method while Stream and FileName will both be null. If RasterCodecs.LoadAsync(String fileName, object userState) is being called, the FileName will contain the same file name string value passed to the method while Uri and Stream will both be null and so on.

Image

Contains the RasterImage class instance that contains the image data being loaded. This instance is the same object returned from the RasterCodecs.LoadAsync method. While the asynchronous operation is running, the value of the RasterImage.IsLoading property will be true indicating that the object is being populated with the image information and should not be used. When the asynchronous operation completes, the RasterCodecs.LoadAsyncCompleted event will fire and Image will contain the final and ready to use object. If an error occurs, this property will be set to null and the object is disposed internally by the toolkit.

Error

Contains any errors that might have occurred during the asynchronous operation. You must check this value when the RasterCodecs.LoadAsyncCompleted event fires and make sure it does not contain a valid Exception object.

Cancelled

Contains a value indicating whether an asynchronous operation has been canceled. For example, by calling RasterCodecs.CancelAsync when using RasterCodecs.LoadAsync with a URL

Example

For an example, refer to RasterCodecs.LoadAsyncCompleted.

Requirements

Target Platforms

Help Version 20.0.2019.12.5
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