GetRowColumnCompressed(IntPtr,IntPtr,Int32,Int32,Int32) Method

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

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

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

'Declaration
 
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

'Usage
 
Dim instance As RasterImage
Dim workBuffer As IntPtr
Dim runBuffer As IntPtr
Dim row As Integer
Dim column As Integer
Dim width As Integer
Dim value As Integer
 
value = instance.GetRowColumnCompressed(workBuffer, runBuffer, row, column, width)

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

 function Leadtools.RasterImage.GetRowColumnCompressed(IntPtr,IntPtr,Int32,Int32,Int32)( 
   workBuffer ,
   runBuffer ,
   row ,
   column ,
   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

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

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

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

      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

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:\Users\Public\Documents\LEADTOOLS Images";
}

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

RasterImage Class
RasterImage Members
Overload List