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StartFeedLoad(Int32,CodecsLoadByteOrder,Int32,Int32) Method
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Leadtools.Codecs Namespace > RasterCodecs Class > StartFeedLoad Method : StartFeedLoad(Int32,CodecsLoadByteOrder,Int32,Int32) Method




bitsPerPixel

Resulting image pixel depth. Valid values are:

ValueMeaning
0Keep the original file's pixel depth (Do not convert).
1 to 8The specified bits per pixel in the resulting image.
1212 bits per pixel in the resulting image.
1616 bits per pixel in the resulting image.
2424 bits per pixel in the resulting image.
3232 bits per pixel in the resulting image.
4848 bits per pixel in the resulting image.
6464 bits per pixel in the resulting image.

order

The desired color order. Possible values are:

ValueMeaning
CodecsLoadByteOrder.RgbRed, green, and blue color order in memory
CodecsLoadByteOrder.BgrBlue, green, and red color order in memory
CodecsLoadByteOrder.Gray12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in the Document/Medical Imaging editions.
CodecsLoadByteOrder.RgbOrGrayLoad 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.BgrOrGrayLoad 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.RommROMM order. ROMM only supports 24 and 48-bit images
CodecsLoadByteOrder.BgrOrGrayOrRommLoad 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 file.
Initializes a file-load process in which you control the input stream with specific number of pages.

Syntax

Visual Basic (Declaration) 
Overloads Public Sub StartFeedLoad( _
   ByVal bitsPerPixel As Integer, _
   ByVal order As CodecsLoadByteOrder, _
   ByVal firstPage As Integer, _
   ByVal lastPage As Integer _
)
Visual Basic (Usage)Copy Code
Dim instance As RasterCodecs
Dim bitsPerPixel As Integer
Dim order As CodecsLoadByteOrder
Dim firstPage As Integer
Dim lastPage As Integer
 
instance.StartFeedLoad(bitsPerPixel, order, firstPage, lastPage)
C# 
public void StartFeedLoad( 
   int bitsPerPixel,
   CodecsLoadByteOrder order,
   int firstPage,
   int lastPage
)
Managed Extensions for C++ 
public: void StartFeedLoad( 
   int bitsPerPixel,
   CodecsLoadByteOrder order,
   int firstPage,
   int lastPage
)
C++/CLI 
public:
void StartFeedLoad( 
   int bitsPerPixel,
   CodecsLoadByteOrder order,
   int firstPage,
   int lastPage
)

Parameters

bitsPerPixel

Resulting image pixel depth. Valid values are:

ValueMeaning
0Keep the original file's pixel depth (Do not convert).
1 to 8The specified bits per pixel in the resulting image.
1212 bits per pixel in the resulting image.
1616 bits per pixel in the resulting image.
2424 bits per pixel in the resulting image.
3232 bits per pixel in the resulting image.
4848 bits per pixel in the resulting image.
6464 bits per pixel in the resulting image.

order

The desired color order. Possible values are:

ValueMeaning
CodecsLoadByteOrder.RgbRed, green, and blue color order in memory
CodecsLoadByteOrder.BgrBlue, green, and red color order in memory
CodecsLoadByteOrder.Gray12 or 16-bit grayscale image. 12 and 16-bit grayscale images are only supported in the Document/Medical Imaging editions.
CodecsLoadByteOrder.RgbOrGrayLoad 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.BgrOrGrayLoad 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.RommROMM order. ROMM only supports 24 and 48-bit images
CodecsLoadByteOrder.BgrOrGrayOrRommLoad 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 file.

Example

Visual BasicCopy Code
RasterCodecs.FeedLoadMulti
      Public Sub FeedLoadMultiExample()
         RasterCodecs.Startup()
         Dim codecs As New RasterCodecs()

         Dim srcFileName As String = "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Eye.gif"
         Dim destFileName As String = "C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\FeedLoadMulti.tif"

         ' Load pages 2 through 5 from the file by reading chunks from the stream
         codecs.StartFeedLoad(0, CodecsLoadByteOrder.BgrOrGray, 2, 5)

         Dim fs As FileStream = File.OpenRead(srcFileName)
         Try
            Const bufferSize As Integer = 1024
            Dim buffer(bufferSize - 1) As Byte

            Dim read As Integer

            Do
               Application.DoEvents()

               read = fs.Read(buffer, 0, bufferSize)
               Console.WriteLine("Feeding {0} bytes", read)
               If (read > 0) Then
                  codecs.FeedLoad(buffer, 0, read)
               End If
            Loop While read > 0 AndAlso Not codecs.IsFeedLoadDone
         Finally
            fs.Close()
         End Try

         Dim image As RasterImage = codecs.StopFeedLoad()
         Console.WriteLine("{0} pages loaded", image.PageCount)

         ' Save the image to disk
         codecs.Save(image, destFileName, RasterImageFormat.Tif, 1, 1, -1, 1, CodecsSavePageMode.Overwrite)
         image.Dispose()

         ' Clean up
         codecs.Dispose()
         RasterCodecs.Shutdown()
      End Sub
C#Copy Code
RasterCodecs.FeedLoadMulti 
      public void FeedLoadMultiExample() 
      { 
         RasterCodecs.Startup(); 
         RasterCodecs codecs = new RasterCodecs(); 
 
         string srcFileName = @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\Eye.gif"; 
         string destFileName = @"C:\Program Files\LEAD Technologies\LEADTOOLS 15\Images\FeedLoadMulti.tif"; 
 
         // Load pages 2 through 5 from the file by reading chunks from the stream 
         codecs.StartFeedLoad(0, CodecsLoadByteOrder.BgrOrGray, 2, 5); 
 
         using(FileStream fs = File.OpenRead(srcFileName)) 
         { 
            const int bufferSize = 1024; 
            byte[] buffer = new byte[bufferSize]; 
 
            int read; 
 
            do 
            { 
               Application.DoEvents(); 
 
               read = fs.Read(buffer, 0, bufferSize); 
               Console.WriteLine("Feeding {0} bytes", read); 
               if(read > 0) 
                  codecs.FeedLoad(buffer, 0, read); 
            } 
            while(read > 0 && !codecs.IsFeedLoadDone); 
         } 
 
         RasterImage image = codecs.StopFeedLoad(); 
         Console.WriteLine("{0} pages loaded", image.PageCount); 
 
         // Save the image to disk 
         codecs.Save(image, destFileName, RasterImageFormat.Tif, 1, 1, -1, 1, CodecsSavePageMode.Overwrite); 
         image.Dispose(); 
 
         // Clean up 
         codecs.Dispose(); 
         RasterCodecs.Shutdown(); 
      }

Remarks

You must call the FeedLoad method to supply buffered data, and you must call StopFeedLoad when the loading is complete.

This file-load process is useful when receiving transmitted images, such as those on the Internet. It works the same way as the Load method, except that your code supplies the image data. The file-load process works as follows:

  1. You call the StartFeedLoad method to initialize the file-load process.
  2. You create a buffer, and each time you fill it with information, you call the FeedLoad method, which sends the data to the file-load process just as if the data were being read from a file on disk.

  3. Whenever it has enough data to do so, the file-load process behaves the same as in the Load method. It allocates and begins loading the image. It calls your LoadImage event handler, if one is specified, whenever it has enough data in its input buffer.

    The file-load process updates information in the RasterImage when it has received enough information to do so. The file-load process will make the first call to your event handler whenever this information is available.

  4. At any time after calling StartFeedLoad, you can call CancelFeedLoad to gracefully abort the feed load operation. This allows you to end the feed load process without throwing an exception.
  5. To end the file-load process, you call the StopFeedLoad method, which cleans up the process, and returns the loaded RasterImage, if successful. If you call this method before supplying the complete file, it will successfully clean up the process, but will throw an exception. You should catch the exception if the load is canceled purposely.
  6. You can also call the IsFeedLoadDone property to check if the framework has enough data to load the pages specified in firstPage and lastPage.

CodecsLoadByteOrder.Gray is only valid for 12 and 16-bit grayscale images. Support for 12 and 16-bit grayscale images is only available in the Document/Medical Imaging editions.

This method cannot be used in combination with StartRedirecting.

Requirements

Target Platforms: Microsoft .NET Framework 2.0, Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also