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LoadAsync(RasterCodecs,ILeadStream,int,CodecsLoadByteOrder,int,int) Method

Summary

Asynchronously loads the specified image stream using specific options.

Syntax

C#

Parameters

rasterCodecs

RasterCodecs object to perform the operation.

stream

A Stream containing the image data to load.

bitsPerPixel

Resulting image pixel depth. Valid values are:

Value Meaning
0 Keep the original file's pixel depth (Do not convert).
1 to 8 The specified bits per pixel in the resulting image.
12 12 bits per pixel in the resulting image.
16 16 bits per pixel in the resulting image.
24 24 bits per pixel in the resulting image.
32 32 bits per pixel in the resulting image.
48 48 bits per pixel in the resulting image.
64 64 bits per pixel in the resulting image.

order
Color order for 16-bit, 24-bit, 32-bit, 48-bit, and 64-bit images. If the resulting image is less than 16 bits per pixel, this will have no effect since palletized images have no order. The following are valid values.

Value Meaning
CodecsLoadByteOrder.Rgb Red, green, and blue color order in memory
CodecsLoadByteOrder.Bgr Blue, green, and red color order in memory
CodecsLoadByteOrder.Gray 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in the Document/Medical Imaging editions.
CodecsLoadByteOrder.RgbOrGray Load the image as red, green, blue OR as a 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are supported in the Document/Medical Imaging editions
CodecsLoadByteOrder.BgrOrGray Load the image as blue, green, red OR as a 12 or 16-bit grayscale image. 12 and 16-bit grayscale images are supported in the Document/Medical Imaging editions
CodecsLoadByteOrder.Romm ROMM order. ROMM only supports 24 and 48-bit images
CodecsLoadByteOrder.BgrOrGrayOrRomm Load the image as red, green, blue OR as a 12 or 16-bit grayscale image OR as ROMM. 12 and 16-bit grayscale images are supported in the Document/Medical Imaging editions only. ROMM only supports 24 and 48-bit color images.

firstPage
1-based index of the first page to load.

lastPage
The 1-based index of the last page to load. Must be greater than or equal to firstPage. You can pass -1 to load from firstPage to the last page in the stream.

Return Value

A Task that represents the asynchronous operation. TResult: The RasterImage object that this method loads. See remarks for the usage of this object.

Remarks

This topic is part of RasterCodecs support for .NET async/await support. Refer to RasterCodecs Async Operations for more information.

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

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.

Example

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
using LeadtoolsExamples.Common; 
 
public async void LoadAsync3Example() 
{ 
   // For .NET Framework: Add a reference to Leadtools.Async to get the async support as extension methods 
   // For .NET Standard: async support is included. 
 
   // Load a TIF image as 24-bits per pixel from a remote URL 
   string address = @"https://demo.leadtools.com/images/tiff/ocr1.tif"; 
   int bitsPerPixel = 24; 
   Uri uri = new Uri(address); 
 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      // Create an ILeadStream object to the URI 
      using (ILeadStream leadStream = await LeadStream.Factory.FromUri(uri)) 
      { 
         using (RasterImage image = await codecs.LoadAsync(leadStream, bitsPerPixel, CodecsLoadByteOrder.BgrOrGray, 1, 1)) 
         { 
            Console.WriteLine("Image loaded from : {0}", uri); 
            Console.WriteLine("Width: {0}", image.ImageWidth); 
            Console.WriteLine("Height: {0}", image.ImageHeight); 
            Console.WriteLine("BitsPerPixel: {0}", image.BitsPerPixel); 
            Console.WriteLine("BytesPerLine: {0}", image.BytesPerLine); 
         } 
      } 
   } 
} 

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Async Sub LoadAsync3Example() 
   ' For .NET Framework: Add a reference To Leadtools.Async To Get the async support As extension methods 
   ' For .NET Standard Async support Is included. 
 
   ' Load a TIF image as 24-bits per pixel from a remote URL 
   Dim address As String = "https://demo.leadtools.com/images/tiff/ocr1.tif" 
   Dim bitsPerPixel As Integer = 24 
 
   Dim uri As New Uri(address) 
 
   Using codecs As New RasterCodecs() 
      ' Create an ILeadStream object to the URI 
      Using stream As ILeadStream = Await LeadStream.Factory.FromUri(uri) 
         Using image As RasterImage = Await codecs.LoadAsync(stream, bitsPerPixel, CodecsLoadByteOrder.BgrOrGray, 1, 1) 
            Console.WriteLine("Image loaded from : {0}", uri) 
            Console.WriteLine("Width: {0}", image.ImageWidth) 
            Console.WriteLine("Height: {0}", image.ImageHeight) 
            Console.WriteLine("BitsPerPixel: {0}", image.BitsPerPixel) 
            Console.WriteLine("BytesPerLine: {0}", image.BytesPerLine) 
         End Using 
      End Using 
   End Using 
End Sub 

Requirements

For .NET Framework: A reference to the Leadtools.Async.dll assembly is required to use this functionality.

For .NET Standard: This functionality is included in the Leadtools.Codecs.dll assembly.

Target Platforms

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