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++/CLI

Java

Python

public int GetRowColumnCompressed( 
   IntPtr workBuffer, 
   IntPtr runBuffer, 
   int row, 
   int column, 
   int width 
)

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 
)

def GetRowColumnCompressed(self,workBuffer,runBuffer,row,column,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.

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 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(LEAD_VARS.ImagesDir, "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(LEAD_VARS.ImagesDir, "IMAGE1_getrowcolcompresed.BMP"), RasterImageFormat.Bmp, 0); 
 
	image.Dispose(); 
	codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}

Requirements

Target Platforms

Reference

RasterImage Class

RasterImage Members

Overload List

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Help Version 22.0.2023.5.16

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