Load(Stream,long,long) Method

Summary

Loads an image file, letting you specify the location of the image data within the stream.

Syntax

C++

public RasterImage Load( 
   Stream stream, 
   long offset, 
   long count 
)

Public Overloads Function Load( _ 
   ByVal stream As Stream, _ 
   ByVal offset As Long, _ 
   ByVal count As Long _ 
) As RasterImage

public: 
RasterImage^ Load(  
   Stream^ stream, 
   int64 offset, 
   int64 count 
)

Parameters

stream
A Stream containing the image data to load.

offset
Offset from the beginning of the stream at which loading should start.

count
Total size of the image file data.

Return Value

The RasterImage object that this method loads.

Remarks

This method can be used to load an image file that is embedded in another stream.

The location of the image is specified as shown in the following simple illustration:

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.

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 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, and 48 and 64-bit color images is only available in the Document/Medical Imaging editions.

For supported formats, refer to Summary of All Supported 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 CodecsLoadOptions.AllPages property controls whether RasterCodecs will try to load all pages or just the first page if the image data contains multiple pages.

Example

This example will load an image located in an offset into a stream

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Svg; 
using LeadtoolsExamples.Common; 
 
public void LoadStreamOffset1Example() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
 
   string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp"); 
   string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_LoadStreamOffset1.bmp"); 
 
   // Create a memory stream, add a custom header then copy the content of the file 
   // into this stream.  After that, load the image from the stream given the offset 
 
   MemoryStream ms = new MemoryStream(); 
 
   // Add some custom header to the stream (4 bytes) 
   int headerSize = 4; 
   for (int i = 0; i < headerSize; i++) 
      ms.WriteByte(0); 
 
   // Now append the file into this stream 
   FileStream fs = File.OpenRead(srcFileName); 
 
   const int bufferSize = 1024; 
   byte[] buffer = new byte[bufferSize]; 
   int bytesRead; 
   do 
   { 
      bytesRead = fs.Read(buffer, 0, bufferSize); 
      if (bytesRead > 0) 
         ms.Write(buffer, 0, bytesRead); 
   } 
   while (bytesRead > 0); 
 
   fs.Close(); 
 
   // Reset the memory stream position to the beginning 
   ms.Position = 0; 
 
   // Now load the image with the offset 
   long offset = headerSize; 
   long count = ms.Length - headerSize; 
   RasterImage image = codecs.Load(ms, offset, count); 
 
   // Save this image back to disk 
   codecs.Save(image, destFileName, RasterImageFormat.Bmp, 24); 
   image.Dispose(); 
 
   // Clean up 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
}

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub LoadStreamOffset1Example() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
 
   Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp") 
   Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1_LoadStreamOffset1.bmp") 
 
   ' Create a memory stream, add a cutsom header then copy the content of the file 
   ' into this stream.  After that, load the image from the stream given the offset 
 
   Dim ms As MemoryStream = New MemoryStream() 
 
   ' Add some custom header to the stream (4 bytes) 
   Dim headerSize As Integer = 4 
   Dim i As Integer = 0 
   Do While i < headerSize 
      ms.WriteByte(0) 
      i += 1 
   Loop 
 
   ' Now append the file into this stream 
   Dim fs As FileStream = File.OpenRead(srcFileName) 
 
   Const bufferSize As Integer = 1024 
   Dim buffer As Byte() = New Byte(bufferSize - 1) {} 
   Dim bytesRead As Integer 
   Do 
      bytesRead = fs.Read(buffer, 0, bufferSize) 
      If bytesRead > 0 Then 
         ms.Write(buffer, 0, bytesRead) 
      End If 
   Loop While bytesRead > 0 
 
   fs.Close() 
 
   ' Reset the memory stream position to the beginning 
   ms.Position = 0 
 
   ' Now load the image with the offset 
   Dim offset As Long = headerSize 
   Dim count As Long = ms.Length - headerSize 
   Dim image As RasterImage = codecs.Load(ms, offset, count) 
 
   ' Save this image back to disk 
   codecs.Save(image, destFileName, RasterImageFormat.Bmp, 24) 
   image.Dispose() 
 
   ' Clean up 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class

Requirements

Target Platforms

Reference

RasterCodecs Class

RasterCodecs Members

Overload List

Loading and Saving Images

Loading and Saving Large TIFF / BigTIFF Files

Speeding Up 1-Bit Documents

Fast File Info

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