GetRowCompressed(WriteOnlyArray<Byte>,WriteOnlyArray<UInt16>,Int32,Int32,Int32) Method

Retrieves one or more rows of 1-bit compressed data from an image that has been loaded in its compressed format.

Syntax

public void GetRowCompressed( 
   WriteOnlyArray<byte> workBuffer,
   WriteOnlyArray<ushort> runBuffer,
   int runBufferOffset,
   int row,
   int lines
)

public void GetRowCompressed( 
   WriteOnlyArray<byte> workBuffer,
   WriteOnlyArray<ushort> runBuffer,
   int runBufferOffset,
   int row,
   int lines
)

 function Leadtools.RasterImage.GetRowCompressed(WriteOnlyArray{Byte},WriteOnlyArray{UInt16},Int32,Int32,Int32)( 
   workBuffer ,
   runBuffer ,
   runBufferOffset ,
   row ,
   lines 
)

public:
void GetRowCompressed( 
   WriteOnlyArray<byte>^ workBuffer,
   WriteOnlyArray<ushort>^ runBuffer,
   int runBufferOffset,
   int row,
   int lines
)

'Declaration
 
Public Overloads Sub GetRowCompressed( _
   ByVal workBuffer As WriteOnlyArray(Of Byte), _
   ByVal runBuffer As WriteOnlyArray(Of UShort), _
   ByVal runBufferOffset As Integer, _
   ByVal row As Integer, _
   ByVal lines As Integer _
)

'Usage
 
Dim instance As RasterImage
Dim workBuffer As WriteOnlyArray(Of Byte)
Dim runBuffer As WriteOnlyArray(Of UShort)
Dim runBufferOffset As Integer
Dim row As Integer
Dim lines As Integer
 
instance.GetRowCompressed(workBuffer, runBuffer, runBufferOffset, row, lines)

Parameters

workBuffer: Optional 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. bytes required = lines * ((Width + 3) * 2). Pass a null reference (Nothing in Visual Basic) to runBuffer if you do not want to use a work buffer.
runBuffer: The output buffer, which will be filled with 1-bit compressed image data.
runBufferOffset: Offset into runBuffer where the copy operation should start.
row: The number of the row to retrieve. The first row is 0, and the last row is 1 less than the image height.
lines: Number of rows to retrieve.

Remarks

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

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#

Public Sub GetRowCompressedExample()
      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)

      ' 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

      ' Adjust the YOffset if the view perspective is bottom left.
      Dim nRow As Integer = 500 ' first row to get.
      Dim nYSize As Integer = 500 ' number of rows to get.

      If image.ViewPerspective = RasterViewPerspective.BottomLeft Then
         nRow = image.Height - nRow - nYSize
      End If

      ' Allocate the buffers.
      Dim pBuffer As Byte() = New Byte(Convert.ToInt32((((image.Width + 31) And Not (31)) / 8)) * nYSize - 1) {} ' Buffer to hold the expanded row.
      Dim pRunBuffer As System.UInt16() = New System.UInt16(((image.Width + 3) * 2) * nYSize - 1) {} ' Buffer to hold the compressed row.

      If image.IsGlobalMemory Then
         image.Access()
      End If
      ' Get the top nRow lines.
      image.GetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)
      ' Expand the compressed data.
      RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)
      ' Invert the data.

      Dim n As Integer = 0
      Do While n < (image.BytesPerLine * nYSize)
         pBuffer(n) = pBuffer(n) Xor Convert.ToByte(&HFF)
         n += 1
      Loop


      ' Compress the inverted data.
      RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize)

      ' Put the inverted, compressed data back into the image.
      image.SetRowCompressed(Nothing, pRunBuffer, 0, nRow, nYSize)

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

      codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "IMAGE1_getrowcompresed.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 GetRowCompressedExample()
   {
      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);

      // This example does not work with rotated view perspectives.
      if((image.ViewPerspective != RasterViewPerspective.TopLeft) || (image.ViewPerspective != RasterViewPerspective.BottomLeft))
         image.ChangeViewPerspective(RasterViewPerspective.TopLeft);

      // Adjust the YOffset if the view perspective is bottom left.
      int nRow = 500; // first row to get.
      int nYSize = 500; // number of rows to get.

      if(image.ViewPerspective == RasterViewPerspective.BottomLeft)
         nRow = image.Height - nRow - nYSize;

      // Allocate the buffers.
      byte[] pBuffer = new byte[Convert.ToInt32((((image.Width + 31) & ~(31)) / 8)) * nYSize]; // Buffer to hold the expanded row.
      ushort[] pRunBuffer = new ushort[((image.Width + 3) * 2) * nYSize]; // Buffer to hold the compressed row.

      if(image.IsGlobalMemory)
         image.Access();
      // Get the top nRow lines.
      image.GetRowCompressed(null, pRunBuffer, 0, nRow, nYSize);
      // Expand the compressed data.
      RasterRleCompressor.ExpandRows(pRunBuffer, pBuffer, 0, image.Width, nYSize);
      // Invert the data.

      for(int n = 0; n < (image.BytesPerLine * nYSize); n++)
         pBuffer[n] ^= 0xff;


      // Compress the inverted data.
      RasterRleCompressor.CompressRows(pRunBuffer, pBuffer, 0, image.Width, nYSize);

      // Put the inverted, compressed data back into the image.
      image.SetRowCompressed(null, pRunBuffer, 0, nRow, nYSize);

      if(image.IsGlobalMemory)
         image.Release();

      codecs.Save(image,Path.Combine(LEAD_VARS.ImagesDir,"IMAGE1_getrowcompresed.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