- stream
- A System.IO.Stream containing the image data to load.
- userState
- A user-defined object that is passed to the method invoked when the asynchronous operation completes.
Visual Basic (Declaration) | |
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Overloads Public Function LoadAsync( _ ByVal stream As Stream, _ ByVal userState As Object _ ) As RasterImage |
Visual Basic (Usage) | ![]() |
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Dim instance As RasterCodecs Dim stream As Stream Dim userState As Object Dim value As RasterImage value = instance.LoadAsync(stream, userState) |
C# | |
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public RasterImage LoadAsync( Stream stream, object userState ) |
C++/CLI | |
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public: RasterImage^ LoadAsync( Stream^ stream, Object^ userState ) |
Parameters
- stream
- A System.IO.Stream containing the image data to load.
- userState
- A user-defined object that is passed to the method invoked when the asynchronous operation completes.
Return Value
The Leadtools.RasterImage object that this method loads. See remarks for the usage of this object.
Visual Basic | ![]() |
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Public Sub LoadAsyncStream1Example() Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp") Dim codecs As New RasterCodecs() ' Now load the image asynchronously AddHandler codecs.LoadAsyncCompleted, AddressOf LoadAsyncStream1Example_LoadAsyncCompleted Dim stream As Stream = File.OpenRead(srcFileName) Dim rasterImageObject As Object = codecs.LoadAsync(stream, Nothing) ' Notice that the returned rasterImageObject is a RasterImage with IsLoading set to true at this point ' The IsLoading will be false (and hence, the object will be usable) when the LoadAsyncCompleteted ' fires. End Sub Private Sub LoadAsyncStream1Example_LoadAsyncCompleted(ByVal sender As Object, ByVal e As CodecsLoadAsyncCompletedEventArgs) If e.Cancelled Then Console.WriteLine("User canceled") ElseIf Not IsNothing(e.Error) Then Console.WriteLine("Error: " + e.Error.Message) Else ' Everything is OK, get the image Dim image As RasterImage = e.Image Console.WriteLine("Image at loaded OK, size: {0} by {1}", image.Width, image.Height) image.Dispose() End If ' We should close the stream here e.Stream.Dispose() ' Unsubscribe to the event and dispose the RasterCodecs object Dim codecs As RasterCodecs = DirectCast(sender, RasterCodecs) RemoveHandler codecs.LoadAsyncCompleted, AddressOf LoadAsyncStream1Example_LoadAsyncCompleted codecs.Dispose() End Sub Public NotInheritable Class LEAD_VARS Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" End Class |
C# | ![]() |
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public void LoadAsyncStream1Example() { string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); RasterCodecs codecs = new RasterCodecs(); // Now load the image asynchronously codecs.LoadAsyncCompleted += new EventHandler<CodecsLoadAsyncCompletedEventArgs>(LoadAsyncStream1Example_LoadAsyncCompleted); Stream stream = File.OpenRead(srcFileName); object rasterImageObject = codecs.LoadAsync(stream, null); // Notice that the returned rasterImageObject is a RasterImage with IsLoading set to true at this point // The IsLoading will be false (and hence, the object will be usable) when the LoadAsyncCompleteted // fires. } private void LoadAsyncStream1Example_LoadAsyncCompleted(object sender, CodecsLoadAsyncCompletedEventArgs e) { if(e.Cancelled) { Console.WriteLine("User canceled"); } else if(e.Error != null) { Console.WriteLine("Error: " + e.Error.Message); } else { // Everything is OK, get the image RasterImage image = e.Image; Console.WriteLine("Image at loaded OK, size: {0} by {1}", image.Width, image.Height); image.Dispose(); } // We should close the stream here e.Stream.Dispose(); // Unsubscribe to the event and dispose the RasterCodecs object RasterCodecs codecs = sender as RasterCodecs; codecs.LoadAsyncCompleted -= new EventHandler<CodecsLoadAsyncCompletedEventArgs>(LoadAsyncStream1Example_LoadAsyncCompleted); codecs.Dispose(); } static class LEAD_VARS { public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; } |
SilverlightCSharp | ![]() |
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SilverlightVB | ![]() |
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The stream can point to any supported image file format and bits per pixel, whether compressed or uncompressed.
This method will load all the pages in 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 stream.
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 options 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 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.
It is recommended that you do not poll for the RasterImage.IsLoading property to check when the image is finished loaded, instead, subscribe to the LoadAsyncCompleted event to get notification on when the RasterCodecs.LoadAsync operation is completed and if 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: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only)