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GetRowColumn(Int32,Int32,IntPtr,Int32) Method
See Also 
Leadtools Namespace > RasterImage Class > GetRowColumn Method : GetRowColumn(Int32,Int32,IntPtr,Int32) Method



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 * NumberOfPixels) / 8;
            if((Image.BitsPerPixel * NumberOfPixels) % 8)
               NumberOfBytes = NumberOfBytes + 1; // Round up if necessary for a 1- or 4-bit image

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 * NumberOfPixels) / 8;
            if((Image.BitsPerPixel * NumberOfPixels) % 8)
               NumberOfBytes = NumberOfBytes + 1; // Round up if necessary for a 1- or 4-bit image

Accepts a column offset to retrieve data from an image and place it in an ummanaged memory buffer.

Syntax

Visual Basic (Declaration) 
Overloads Public Function GetRowColumn( _
   ByVal row As Integer, _
   ByVal column As Integer, _
   ByVal buffer As IntPtr, _
   ByVal bufferCount As Integer _
) As Integer
Visual Basic (Usage)Copy Code
Dim instance As RasterImage
Dim row As Integer
Dim column As Integer
Dim buffer As IntPtr
Dim bufferCount As Integer
Dim value As Integer
 
value = instance.GetRowColumn(row, column, buffer, bufferCount)
C# 
public int GetRowColumn( 
   int row,
   int column,
   IntPtr buffer,
   int bufferCount
)
C++/CLI 
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 * NumberOfPixels) / 8;
            if((Image.BitsPerPixel * NumberOfPixels) % 8)
               NumberOfBytes = NumberOfBytes + 1; // Round up if necessary for a 1- or 4-bit image

Return Value

The number of bytes copied.

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(Int32,Int32,Byte[],Int32,Int32) to invert the colors of a rectangle in the upper left part of the displayed image.

Visual BasicCopy Code
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.
      If image.IsGlobalMemory Then
         image.Access()
      End If
      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
      If image.IsGlobalMemory Then
         image.Release()
      End If

      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:\Users\Public\Documents\LEADTOOLS Images"
End Class
C#Copy Code
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.
      if(image.IsGlobalMemory)
         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);
      }
      if(image.IsGlobalMemory)
         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:\Users\Public\Documents\LEADTOOLS Images";
}
SilverlightCSharpCopy Code
public void GetRowColumnExample(RasterImage image, Stream destStream)
{
   // 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.
   if (image.IsGlobalMemory)
      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);
   }
   if (image.IsGlobalMemory)
      image.Release();

   RasterCodecs codecs = new RasterCodecs();
   codecs.Save(image, destStream, RasterImageFormat.Bmp, 0);

   image.Dispose();
}
SilverlightVBCopy Code
Public Sub GetRowColumnExample(ByVal image As RasterImage, ByVal destStream As Stream)
   ' 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.
   If image.IsGlobalMemory Then
      image.Access()
   End If
   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 &HFF
         col += 1
      Loop

      image.SetRowColumn(i, xOffset, Buffer, 0, xSize * 3)
      i += 1
   Loop
   If image.IsGlobalMemory Then
      image.Release()
   End If

   Dim codecs As RasterCodecs = New RasterCodecs()
   codecs.Save(image, destStream, RasterImageFormat.Bmp, 0)

   image.Dispose()
End Sub

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.

Requirements

Target Platforms: Silverlight, Windows XP, Windows Server 2003 family, Windows Server 2008 family, Windows Vista, Windows 7, MAC OS/X (Intel Only), Windows Phone 7

See Also