Public Overloads Sub GetRowCompressed( _
   ByVal workBuffer As IntPtr, _
   ByVal runBuffer As IntPtr, _
   ByVal row As Integer, _
   ByVal lines As Integer _
) 

Visual Basic (Usage)	Copy Code
Dim instance As RasterImage Dim workBuffer As IntPtr Dim runBuffer As IntPtr Dim row As Integer Dim lines As Integer   instance.GetRowCompressed(workBuffer, runBuffer, row, lines)

public void GetRowCompressed( 
   IntPtr workBuffer,
   IntPtr runBuffer,
   int row,
   int lines
)

public:
void GetRowCompressed( 
   IntPtr workBuffer,
   IntPtr runBuffer,
   int row,
   int lines
) 

Parameters

workBuffer

Pointer to optional work unmanaged memory 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 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.

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.

This example demonstrates the low-level methods for accessing 1-bit compressed image data. It demonstrates the ability to get and put rows, and the ability to process rows in buffer-to-buffer processing. The result of the function is an the first 50 lines are inverted.

Visual Basic

Copy Code

Public Sub GetRowCompressedExample()    RasterCodecs.Startup()    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(LeadtoolsExamples.Common.ImagesPath.Path + "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, LeadtoolsExamples.Common.ImagesPath.Path + "IMAGE1_getrowcompresed.BMP", RasterImageFormat.Bmp, 0)    image.Dispose()    codecs.Dispose()    RasterCodecs.Shutdown() End Sub

C#

Copy Code

public void GetRowCompressedExample()  {     RasterCodecs.Startup();     RasterCodecs codecs = new RasterCodecs();     // Load the bitmap, at 1 bit per pixel, compressed     codecs.Options.Load.Compressed = true;     RasterImage image = codecs.Load(LeadtoolsExamples.Common.ImagesPath.Path + "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, LeadtoolsExamples.Common.ImagesPath.Path + "IMAGE1_getrowcompresed.BMP", RasterImageFormat.Bmp, 0);       image.Dispose();     codecs.Dispose();     RasterCodecs.Shutdown();  }

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.

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

Reference