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GetRowColumnCompressed(IntPtr,IntPtr,int,int,int) Method

Summary

Retrieves (into an unmanaged memory buffer) a row (or part of a row) of 1-bit compressed data from an image that has been loaded in its compressed format.

Syntax
C#
VB
Java
C++
public int GetRowColumnCompressed( 
   IntPtr workBuffer, 
   IntPtr runBuffer, 
   int row, 
   int column, 
   int width 
) 
Public Overloads Function GetRowColumnCompressed( _ 
   ByVal workBuffer As IntPtr, _ 
   ByVal runBuffer As IntPtr, _ 
   ByVal row As Integer, _ 
   ByVal column As Integer, _ 
   ByVal width As Integer _ 
) As Integer 
public int getRowColumnCompressed( 
  byte[] workBuffer,  
  short[] runBuffer,  
  int row,  
  int column,  
  int width 
) 
public: 
int GetRowColumnCompressed(  
   IntPtr workBuffer, 
   IntPtr runBuffer, 
   int row, 
   int column, 
   int width 
)  

Parameters

workBuffer
Pointer to optional unmanaged memory 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. The size of this buffer should be the same as the BytesPerLine property. Pass IntPtr.Zero for workBuffer if you do not want to use the work buffer

runBuffer
Pointer to the output unmanaged memory buffer, which will be filled with 1-bit compressed image data. Calculate the required size of this buffer as follows: bytes required = (Width + 3) * 2.

row
The number of the row to retrieve. The first row is 0, and the last row is 1 less than the image height.

column
The column offset within the row to retrieve. The first column offset is 0, and the last column offset is 1 less than the image width.

width
The number of pixels to retrieve.

Return Value

The number of pixels processed.

Remarks

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

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.

Example

This example demonstrates the low-level methods for accessing 1-bit compressed bitmap data. It demonstrates the ability to get and set partial rows, and the ability to process partial rows in buffer-to-buffer processing. The result of the method is an inverted rectangle in the middle of the image.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Core; 
using Leadtools.ImageProcessing.Color; 
using Leadtools.Dicom; 
using Leadtools.Drawing; 
using Leadtools.Controls; 
using LeadtoolsExamples.Common; 
using Leadtools.Svg; 
 
public void GetRowColumnCompressedExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   // Load the bitmap, at 1 bit per pixel, compressed 
   codecs.Options.Load.Compressed = true; 
   RasterImage image = codecs.Load(Path.Combine(ImagesPath.Path, "OCR1.TIF"), 1, Leadtools.Codecs.CodecsLoadByteOrder.Bgr, 1, 1); 
 
   int xOffset;   // Column offset of the rectangle to process. 
   int xSize;     // Pixel width of the rectangle to process. 
   int yOffset;   // Row offset of the rectangle to process. 
   int ySize;     // Pixel height of the rectangle to process. 
   int i, n;       // Counters. 
 
   byte[] buffer;      // Buffer to hold the expanded row. 
   ushort[] runBuffer; // Buffer to hold the compressed row. 
   byte[] workBuffer;  // Work buffer. 
 
   // This example does not work with rotated view perspectives. 
   if ((image.ViewPerspective != RasterViewPerspective.TopLeft) || (image.ViewPerspective != RasterViewPerspective.BottomLeft)) 
      image.ChangeViewPerspective(RasterViewPerspective.TopLeft); 
 
   // Specify a rectangle in the middle right part of the displayed image. 
   xOffset = image.Width / 3; 
   xSize = image.Width - xOffset; 
   yOffset = image.Height / 3; 
   ySize = image.Height / 3; 
   // Adjust the YOffset if the view perspective is bottom left. 
   if (image.ViewPerspective == RasterViewPerspective.BottomLeft) 
   { 
      yOffset = image.Height - yOffset - ySize; 
   } 
 
   if (image.IsGlobalMemory) 
      image.Access(); 
   // Allocate the buffers. 
   buffer = new Byte[(xSize + 7) / 8]; 
   runBuffer = new ushort[(xSize + 3) * 2]; 
   workBuffer = new Byte[image.BytesPerLine]; 
   // Invert the colors of pixels in the left half of the rectangle. 
   // Notice that we get the whole rectangle, but process only half of it. 
   for (i = yOffset; i < (yOffset + ySize); i++) 
   { 
      image.GetRowColumnCompressed(workBuffer, runBuffer, 0, i, xOffset, xSize); 
      RasterRleCompressor.ExpandRow(runBuffer, buffer, 0, 0, xSize); 
      for (n = 0; n < (xSize / 16); n++) 
         buffer[n] ^= 0xFF; 
      RasterRleCompressor.CompressRow(runBuffer, buffer, 0, 0, xSize); 
      image.SetRowColumnCompressed(workBuffer, runBuffer, 0, i, xOffset, xSize); 
 
   } 
   if (image.IsGlobalMemory) 
      image.Release(); 
 
   codecs.Save(image, Path.Combine(ImagesPath.Path, "IMAGE1_getrowcolcompresed.BMP"), RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.ImageProcessing 
Imports Leadtools.ImageProcessing.Core 
Imports Leadtools.ImageProcessing.Color 
Imports Leadtools.Controls 
Imports Leadtools.Dicom 
Imports Leadtools.Drawing 
Imports Leadtools.Svg 
 
Public Sub GetRowColumnCompressedExample() 
   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(Path.Combine(LEAD_VARS.ImagesDir, "OCR1.TIF"), 1, CodecsLoadByteOrder.Bgr, 1, 1) 
 
   Dim xOffset As Integer ' Column offset of the rectangle to process. 
   Dim xSize As Integer ' Pixel width of the rectangle to process. 
   Dim yOffset As Integer ' Row offset of the rectangle to process. 
   Dim ySize As Integer ' Pixel height of the rectangle to process. 
   Dim i, n As Integer ' Counters. 
 
   Dim buffer As Byte() ' Buffer to hold the expanded row. 
   Dim runBuffer As System.UInt16() ' Buffer to hold the compressed row. 
   Dim workBuffer As Byte() ' Work buffer. 
 
   ' 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 
 
   ' Specify a rectangle in the middle right part of the displayed image. 
   xOffset = image.Width \ 3 
   xSize = image.Width - xOffset 
   yOffset = image.Height \ 3 
   ySize = image.Height \ 3 
   ' Adjust the YOffset if the view perspective is bottom left. 
   If image.ViewPerspective = RasterViewPerspective.BottomLeft Then 
      yOffset = image.Height - yOffset - ySize 
   End If 
 
   image.Access() 
   ' Allocate the buffers. 
   buffer = New Byte((xSize + 7) \ 8 - 1) {} 
   runBuffer = New System.UInt16((xSize + 3) * 2 - 1) {} 
   workBuffer = New Byte(image.BytesPerLine - 1) {} 
   ' Invert the colors of pixels in the left half of the rectangle. 
   ' Notice that we get the whole rectangle, but process only half of it. 
   i = yOffset 
   Do While i < (yOffset + ySize) 
      image.GetRowColumnCompressed(workBuffer, runBuffer, 0, i, xOffset, xSize) 
      RasterRleCompressor.ExpandRow(runBuffer, buffer, 0, 0, xSize) 
      n = 0 
      Do While n < (xSize / 16) 
         buffer(n) = buffer(n) Xor Convert.ToByte(&HFF) 
         n += 1 
      Loop 
      RasterRleCompressor.CompressRow(runBuffer, buffer, 0, 0, xSize) 
      image.SetRowColumnCompressed(workBuffer, runBuffer, 0, i, xOffset, xSize) 
 
      i += 1 
   Loop 
   image.Release() 
 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcolcompresed.BMP"), RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
   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

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