Leadtools Send comments on this topic. | Back to Introduction - All Topics | Help Version 16.5.9.25
GetRowCompressed(Byte[],UInt16[],Int32,Int32,Int32) Method
See Also  Example
Leadtools Namespace > RasterImage Class > GetRowCompressed Method : GetRowCompressed(Byte[],UInt16[],Int32,Int32,Int32) Method



workBuffer
Optional work buffer. Allocating the work buffer speeds processing if you call this method more than once, because if you do not allocate a work buffer, the method allocates and frees a temporary buffer each time it is called. bytes required = lines * ((Width + 3) * 2). Pass a null reference (Nothing in Visual Basic) to runBuffer if you do not want to use a work buffer.
runBuffer
The output buffer, which will be filled with 1-bit compressed image data.
runBufferOffset
Offset into runBuffer where the copy operation should start.
row
The number of the row to retrieve. The first row is 0, and the last row is 1 less than the image height.
lines
Number of rows to retrieve.
Retrieves one or more rows of 1-bit compressed data from an image that has been loaded in its compressed format.

Syntax

Visual Basic (Declaration) 
<CLSCompliantAttribute(False)>
Public Overloads Sub GetRowCompressed( _
   ByVal workBuffer() As Byte, _
   ByVal runBuffer() As UShort, _
   ByVal runBufferOffset As Integer, _
   ByVal row As Integer, _
   ByVal lines As Integer _
)
Visual Basic (Usage)Copy Code
Dim instance As RasterImage
Dim workBuffer() As Byte
Dim runBuffer() As UShort
Dim runBufferOffset As Integer
Dim row As Integer
Dim lines As Integer
 
instance.GetRowCompressed(workBuffer, runBuffer, runBufferOffset, row, lines)
C# 
[CLSCompliantAttribute(false)]
public void GetRowCompressed( 
   byte[] workBuffer,
   ushort[] runBuffer,
   int runBufferOffset,
   int row,
   int lines
)
C++/CLI 
[CLSCompliantAttribute(false)]
public:
void GetRowCompressed( 
   array<byte>^ workBuffer,
   array<ushort>^ runBuffer,
   int runBufferOffset,
   int row,
   int lines
)

Parameters

workBuffer
Optional work buffer. Allocating the work buffer speeds processing if you call this method more than once, because if you do not allocate a work buffer, the method allocates and frees a temporary buffer each time it is called. bytes required = lines * ((Width + 3) * 2). Pass a null reference (Nothing in Visual Basic) to runBuffer if you do not want to use a work buffer.
runBuffer
The output buffer, which will be filled with 1-bit compressed image data.
runBufferOffset
Offset into runBuffer where the copy operation should start.
row
The number of the row to retrieve. The first row is 0, and the last row is 1 less than the image height.
lines
Number of rows to retrieve.

Example

This example demonstrates the low-level methods for accessing 1-bit compressed image data. It demonstrates the ability to get and put rows, and the ability to process rows in buffer-to-buffer processing. The result of the function is an the first 50 lines are inverted.

Visual BasicCopy Code
Public Sub GetRowCompressedExample()
   RasterCodecs.Startup()
   Dim codecs As RasterCodecs = New RasterCodecs()
   ' Load the bitmap, at 1 bit per pixel, compressed
   codecs.Options.Load.Compressed = True
   Dim image As RasterImage = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "OCR1.TIF", 1, CodecsLoadByteOrder.Bgr, 1, 1)

   ' This example does not work with rotated view perspectives.
   If (image.ViewPerspective <> RasterViewPerspective.TopLeft) OrElse (image.ViewPerspective <> RasterViewPerspective.BottomLeft) Then
      image.ChangeViewPerspective(RasterViewPerspective.TopLeft)
   End If

   ' Adjust the YOffset if the view perspective is bottom left.
   Dim nRow As Integer = 500 ' first row to get.
   Dim nYSize As Integer = 500 ' number of rows to get.

   If image.ViewPerspective = RasterViewPerspective.BottomLeft Then
      nRow = image.Height - nRow - nYSize
   End If

   ' Allocate the buffers.
   Dim pBuffer As Byte() = New Byte(Convert.ToInt32((((image.Width + 31) And Not (31)) / 8)) * nYSize - 1) {} ' Buffer to hold the expanded row.
   Dim pRunBuffer As System.UInt16() = New System.UInt16(((image.Width + 3) * 2) * nYSize - 1) {} ' Buffer to hold the compressed row.

   If image.IsGlobalMemory Then
      image.Access()
   End If
   ' Get the top nRow lines.
   image.GetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)
   ' Expand the compressed data.
   RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)
   ' Invert the data.

   Dim n As Integer = 0
   Do While n < (image.BytesPerLine * nYSize)
      pBuffer(n) = pBuffer(n) Xor Convert.ToByte(&HFF)
      n += 1
   Loop


   ' Compress the inverted data.
   RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)

   ' Put the inverted, compressed data back into the image.
   image.SetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)

   If image.IsGlobalMemory Then
      image.Release()
   End If

   codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "IMAGE1_getrowcompresed.BMP", RasterImageFormat.Bmp, 0)

   image.Dispose()
   codecs.Dispose()
   RasterCodecs.Shutdown()
End Sub
C#Copy Code
public void GetRowCompressedExample() 
{ 
   RasterCodecs.Startup(); 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the bitmap, at 1 bit per pixel, compressed 
   codecs.Options.Load.Compressed = true; 
   RasterImage image = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "OCR1.TIF", 1, Leadtools.Codecs.CodecsLoadByteOrder.Bgr, 1, 1); 
 
   // This example does not work with rotated view perspectives. 
   if((image.ViewPerspective != RasterViewPerspective.TopLeft) || (image.ViewPerspective != RasterViewPerspective.BottomLeft)) 
      image.ChangeViewPerspective(RasterViewPerspective.TopLeft); 
 
   // Adjust the YOffset if the view perspective is bottom left. 
   int nRow = 500; // first row to get. 
   int nYSize = 500; // number of rows to get. 
 
   if(image.ViewPerspective == RasterViewPerspective.BottomLeft) 
      nRow = image.Height - nRow - nYSize; 
 
   // Allocate the buffers. 
   byte[] pBuffer = new byte[Convert.ToInt32((((image.Width + 31) & ~(31)) / 8)) * nYSize]; // Buffer to hold the expanded row. 
   ushort[] pRunBuffer = new ushort[((image.Width + 3) * 2) * nYSize]; // Buffer to hold the compressed row. 
 
   if(image.IsGlobalMemory) 
      image.Access(); 
   // Get the top nRow lines. 
   image.GetRowCompressed(null, pRunBuffer, 0, nRow, nYSize); 
   // Expand the compressed data. 
   RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize); 
   // Invert the data. 
 
   for(int n = 0; n < (image.BytesPerLine * nYSize); n++) 
      pBuffer[n] ^= 0xff; 
 
 
   // Compress the inverted data. 
   RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize); 
 
   // Put the inverted, compressed data back into the image. 
   image.SetRowCompressed(null, pRunBuffer, 0, nRow, nYSize); 
 
   if(image.IsGlobalMemory) 
      image.Release(); 
 
   codecs.Save(image, LeadtoolsExamples.Common.ImagesPath.Path + "IMAGE1_getrowcompresed.BMP", RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
   RasterCodecs.Shutdown(); 
}

Remarks

This method is available in the (Document/Medical only) Toolkits.

This method is useful for working with 1-bit images that are loaded in their compressed formats for faster loading and display.

For more information, refer to Speeding Up 1-Bit Documents.

Requirements

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

See Also