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GetRowColumn(int,int,IntPtr,int) Method

Summary
Accepts a column offset to retrieve data from an image and place it in an unmanaged memory buffer.
Syntax
C#
VB
C++
Java
public int GetRowColumn( 
   int row, 
   int column, 
   IntPtr buffer, 
   int bufferCount 
) 
Public Overloads Function GetRowColumn( _ 
   ByVal row As Integer, _ 
   ByVal column As Integer, _ 
   ByVal buffer As IntPtr, _ 
   ByVal bufferCount As Integer _ 
) As Integer 
public long getRowColumn( 
  int row,  
  int column,  
  byte[] buffer,  
  long bufferCount 
) 
public: 
int GetRowColumn(  
   int row, 
   int column, 
   IntPtr buffer, 
   int bufferCount 
)

Parameters

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

buffer
Pointer to an unmanaged buffer to hold the image data that this method gets. The buffer will be filled with uncompressed data.

bufferCount
The number of bytes to retrieve. Consider the bits per pixel, and avoid specifying a number that goes past the end of the row.

For a 1-bit image, each byte represents 8 pixels. For a 4-bit image, each byte represents 2 pixels. For an 8-bit image, each byte represents 1 pixel. For a 16-bit image, every 2 bytes represents one pixel. For 24-bit images, every three bytes represents one pixel. For a 32-bit image, every four bytes represents one pixel. For 48-bit images, every six bytes represents one pixel. For 64-bit images, every eight bytes represents one pixel.

You can use the image BitsPerPixel property with integer math to calculate the number of bytes needed for a particular number of pixels. For example 

NumberOfBytes = Image.BitsPerPixel * (Image.Width * Image.Height + 7) / 8;

Return Value

The number of bytes copied.

Remarks

By using this low-level method to get any part of a row, you can write a procedure that accesses a single pixel or a rectangular area within the image.

This method accepts an offset parameter ( column) in pixels and a length ( bufferCount) in bytes. Therefore, you must consider the bits per pixel of the image when specifying these parameters. The following table describes the rules:

Bits Per Pixel Column Offset (in Pixels) Bytes to Get
1 Must be a multiple of 8 (such as 0, 8, or 16). Can be any number up to the end of the row. Consider that there are 8 pixels per byte.
4 Must be an even number (such as 0, 2, or 4). Can be any number up to the end of the row. Consider that there are 2 pixels per byte.
8 Can be any column within the image. Can be any number up to the end of the row. Consider that there is 1 pixel per byte.
16 Can be any column within the image. Must be a multiple of 2 (such as 2, 4, or 6), because there are 2 bytes per pixel.
24 Can be any column within the image. Must be a multiple of 3 (such as 3, 6, or 9), because there are 3 bytes per pixel.
32 Can be any column within the image. Must be a multiple of 4 (such as 4, 8, or 12), because there are 4 bytes per pixel.

The image memory must be locked when you use this method. Normally, you can call Access to lock the memory before starting an operation that uses this method. Then call Release when the operation is finished.

Color order is determined by the Order property of the RasterImage object. This value can be RasterByteOrder.Rgb, RasterByteOrder.Bgr, or RasterByteOrder.Romm.

RasterByteOrder.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.

For more information, refer to Introduction to Image Processing With LEADTOOLS.

Example

This example is designed to work with images that have a bottom-left or top-left view perspective. This example uses GetRowColumn and SetRowColumn to invert the colors of a rectangle in the upper left part of the displayed 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 Leadtools.Svg; 
 
 
public void GetRowColumnExample() 
{ 
	RasterCodecs codecs = new RasterCodecs(); 
	RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP")); 
 
	// 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 top left part of the displayed image. 
	int xOffset = Convert.ToInt32(image.Width / 8); // Column offset of the rectangle to process. 
	int xSize = Convert.ToInt32(image.Width / 3); // Pixel width of the rectangle to process. 
	int yOffset = Convert.ToInt32(image.Height / 8); // Row offset of the rectangle to process. 
	int ySize = Convert.ToInt32(image.Height / 3); // Pixel height of the rectangle to process. 
 
	// Adjust the YOffset if the view perspective is bottom left. 
	if (image.ViewPerspective == RasterViewPerspective.BottomLeft) 
		yOffset = image.Height - yOffset - ySize; 
 
	// Allocate the buffer. 
	byte[] Buffer = new byte[xSize * 3]; 
 
	// Invert the colors of pixels in the rectangle. 
	image.Access(); 
	for (int i = yOffset; i < yOffset + ySize; i++) 
	{ 
		image.GetRowColumn(i, xOffset, Buffer, 0, xSize * 3); 
 
		for (int col = 0; col < xSize * 3; col++) 
			Buffer[col] ^= 0xFF; 
 
		image.SetRowColumn(i, xOffset, Buffer, 0, xSize * 3); 
	} 
	image.Release(); 
 
	codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcol.BMP"), RasterImageFormat.Bmp, 0); 
 
	image.Dispose(); 
	codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS21\Resources\Images"; 
} 
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 GetRowColumnExample() 
   Dim codecs As RasterCodecs = New RasterCodecs() 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1.CMP")) 
 
   ' 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 top left part of the displayed image. 
   Dim xOffset As Integer = Convert.ToInt32(image.Width / 8) ' Column offset of the rectangle to process. 
   Dim xSize As Integer = Convert.ToInt32(image.Width \ 3) ' Pixel width of the rectangle to process. 
   Dim yOffset As Integer = Convert.ToInt32(image.Height / 8) ' Row offset of the rectangle to process. 
   Dim ySize As Integer = Convert.ToInt32(image.Height \ 3) ' Pixel height of the rectangle to process. 
 
   ' Adjust the YOffset if the view perspective is bottom left. 
   If image.ViewPerspective = RasterViewPerspective.BottomLeft Then 
      yOffset = image.Height - yOffset - ySize 
   End If 
 
   ' Allocate the buffer. 
   Dim Buffer As Byte() = New Byte(xSize * 3 - 1) {} 
 
   ' Invert the colors of pixels in the rectangle. 
   image.Access() 
   Dim i As Integer = yOffset 
   Do While i < yOffset + ySize 
      image.GetRowColumn(i, xOffset, Buffer, 0, xSize * 3) 
 
      Dim col As Integer = 0 
      Do While col < xSize * 3 
         Buffer(col) = Buffer(col) Xor Convert.ToByte(&HFF) 
         col += 1 
      Loop 
 
      image.SetRowColumn(i, xOffset, Buffer, 0, xSize * 3) 
      i += 1 
   Loop 
   image.Release() 
 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcol.BMP"), RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\LEADTOOLS21\Resources\Images" 
End Class
Requirements

Target Platforms

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