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StartCompress(Int32,Int32,Int32,RasterByteOrder,RasterViewPerspective,Int32,Byte[],Int32,Int32,CodecsCompression,CodecsCompressDataCallback) Method
See Also 
Leadtools.Codecs Namespace > RasterCodecs Class > StartCompress Method : StartCompress(Int32,Int32,Int32,RasterByteOrder,RasterViewPerspective,Int32,Byte[],Int32,Int32,CodecsCompression,CodecsCompressDataCallback) Method



width
The image being compressed width in pixels.
height
The image being compressed height in pixels.
bitsPerPixel
The image being compressed bits/pixel value.
order
The image being compressed byte order.
viewPerspective
The image being compressed view perspective value.
inputDataLength
Size in bytes of the input image data.
outputData
Array of bytes which will be filled with the compressed data.
outputDataIndex
Index into outputData where the compressed data should be inserted.
outputDataLength
Size of outputData in bytes.
compression

Type of compression to use. Valid values are:

Value Meaning
CodecsCompression.Cmp LEAD CMP compression format
CodecsCompression.Jpeg444 JPEG File Interchange Format using YUV 4:4:4 color spacing
CodecsCompression.Jpeg422 JPEG File Interchange Format using YUV 4:2:2 color spacing
CodecsCompression.Jpeg411 JPEG File Interchange Format using YUV 4:1:1 color spacing
CodecsCompression.TifJpeg444 JPEG JTIF using YUV 4:4:4 color spacing
CodecsCompression.TifJpeg422 JPEG JTIF using YUV 4:2:2 color spacing
CodecsCompression.TifJpeg411 JPEG JTIF using YUV 4:1:1 color spacing
CodecsCompression.Lead0 LEAD 1 bit, lossless compression
CodecsCompression.Lead1 LEAD 1 bit, excellent compression
CodecsCompression.TiffCcitt TIFF CCITT
CodecsCompression.TiffCcittG3Fax1Dim CCITT Group 3 one dimensional
CodecsCompression.TiffCcittG3Fax2Dim CCITT Group 3 two dimensional
CodecsCompression.TiffCcittG4Fax CCITT Group 4 two dimensional

callback
The callback method responsible for writing or handling the compressed data.
width
The image being compressed width in pixels.
height
The image being compressed height in pixels.
bitsPerPixel
The image being compressed bits/pixel value.
order
The image being compressed byte order.
viewPerspective
The image being compressed view perspective value.
inputDataLength
Size in bytes of the input image data.
outputData
Array of bytes which will be filled with the compressed data.
outputDataIndex
Index into outputData where the compressed data should be inserted.
outputDataLength
Size of outputData in bytes.
compression

Type of compression to use. Valid values are:

Value Meaning
CodecsCompression.Cmp LEAD CMP compression format
CodecsCompression.Jpeg444 JPEG File Interchange Format using YUV 4:4:4 color spacing
CodecsCompression.Jpeg422 JPEG File Interchange Format using YUV 4:2:2 color spacing
CodecsCompression.Jpeg411 JPEG File Interchange Format using YUV 4:1:1 color spacing
CodecsCompression.TifJpeg444 JPEG JTIF using YUV 4:4:4 color spacing
CodecsCompression.TifJpeg422 JPEG JTIF using YUV 4:2:2 color spacing
CodecsCompression.TifJpeg411 JPEG JTIF using YUV 4:1:1 color spacing
CodecsCompression.Lead0 LEAD 1 bit, lossless compression
CodecsCompression.Lead1 LEAD 1 bit, excellent compression
CodecsCompression.TiffCcitt TIFF CCITT
CodecsCompression.TiffCcittG3Fax1Dim CCITT Group 3 one dimensional
CodecsCompression.TiffCcittG3Fax2Dim CCITT Group 3 two dimensional
CodecsCompression.TiffCcittG4Fax CCITT Group 4 two dimensional

callback
The callback method responsible for writing or handling the compressed data.
Initializes the buffered compression engine.

Syntax

Visual Basic (Declaration) 
Overloads Public Sub StartCompress( _
   ByVal width As Integer, _
   ByVal height As Integer, _
   ByVal bitsPerPixel As Integer, _
   ByVal order As RasterByteOrder, _
   ByVal viewPerspective As RasterViewPerspective, _
   ByVal inputDataLength As Integer, _
   ByVal outputData() As Byte, _
   ByVal outputDataIndex As Integer, _
   ByVal outputDataLength As Integer, _
   ByVal compression As CodecsCompression, _
   ByVal callback As CodecsCompressDataCallback _
) 
Visual Basic (Usage)Copy Code
Dim instance As RasterCodecs
Dim width As Integer
Dim height As Integer
Dim bitsPerPixel As Integer
Dim order As RasterByteOrder
Dim viewPerspective As RasterViewPerspective
Dim inputDataLength As Integer
Dim outputData() As Byte
Dim outputDataIndex As Integer
Dim outputDataLength As Integer
Dim compression As CodecsCompression
Dim callback As CodecsCompressDataCallback
 
instance.StartCompress(width, height, bitsPerPixel, order, viewPerspective, inputDataLength, outputData, outputDataIndex, outputDataLength, compression, callback)

Parameters

width
The image being compressed width in pixels.
height
The image being compressed height in pixels.
bitsPerPixel
The image being compressed bits/pixel value.
order
The image being compressed byte order.
viewPerspective
The image being compressed view perspective value.
inputDataLength
Size in bytes of the input image data.
outputData
Array of bytes which will be filled with the compressed data.
outputDataIndex
Index into outputData where the compressed data should be inserted.
outputDataLength
Size of outputData in bytes.
compression

Type of compression to use. Valid values are:

Value Meaning
CodecsCompression.Cmp LEAD CMP compression format
CodecsCompression.Jpeg444 JPEG File Interchange Format using YUV 4:4:4 color spacing
CodecsCompression.Jpeg422 JPEG File Interchange Format using YUV 4:2:2 color spacing
CodecsCompression.Jpeg411 JPEG File Interchange Format using YUV 4:1:1 color spacing
CodecsCompression.TifJpeg444 JPEG JTIF using YUV 4:4:4 color spacing
CodecsCompression.TifJpeg422 JPEG JTIF using YUV 4:2:2 color spacing
CodecsCompression.TifJpeg411 JPEG JTIF using YUV 4:1:1 color spacing
CodecsCompression.Lead0 LEAD 1 bit, lossless compression
CodecsCompression.Lead1 LEAD 1 bit, excellent compression
CodecsCompression.TiffCcitt TIFF CCITT
CodecsCompression.TiffCcittG3Fax1Dim CCITT Group 3 one dimensional
CodecsCompression.TiffCcittG3Fax2Dim CCITT Group 3 two dimensional
CodecsCompression.TiffCcittG4Fax CCITT Group 4 two dimensional

callback
The callback method responsible for writing or handling the compressed data.

Example

This example demonstrates low-level image compression using StartCompress(Int32,Int32,Int32,RasterByteOrder,RasterViewPerspective,Int32,Byte[],Int32,Int32,CodecsCompression,CodecsCompressDataCallback), Compress(Byte[],Int32) and StopCompress. The callback method for writing the output is included at the end of the example

Visual BasicCopy Code
Public Sub CompressExample()
      Dim codecs As RasterCodecs = New RasterCodecs()

      Dim srcFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")
      Dim destFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Image1_CompressData.cmp")

      ' Load the image to at 24-bits per pixel
      Dim image As RasterImage = codecs.Load(srcFileName, 24, CodecsLoadByteOrder.Bgr, 1, 1)
      If image.ViewPerspective <> RasterViewPerspective.TopLeft Then
         image.ChangeViewPerspective(RasterViewPerspective.TopLeft)
      End If

      ' Create the output file
      _compressStream = File.Create(destFileName)

      ' Calculate the bytes per line in the input buffer, without padding 
      Dim lineBytes As Integer = image.Width * 3

      ' Allocate a buffer for the incoming uncompressed data. Note that we
      '  are compressing 16 lines at a time. You should always use multiples of 16
      Dim inBuffer As Byte() = New Byte(16 * lineBytes - 1) {}

      ' Allocate an output buffer. This is where the compressed data will
      ' go.  Note that this allocates 1024-byte packets. 
      Dim outBuffer As Byte() = New Byte(1023) {}

      ' Lock down the image
      image.Access()

      ' Initialize the compression engine
      codecs.Options.Jpeg.Save.CmpQualityFactorPredefined = CodecsCmpQualityFactorPredefined.QualityAndSize
      codecs.StartCompress(image.Width, image.Height, image.BitsPerPixel, image.Order, image.ViewPerspective, 16 * lineBytes, outBuffer, 0, outBuffer.Length, CodecsCompression.Cmp, AddressOf MyCodecsCompressDataCallback)

      ' Compress the data
      Dim i As Integer = 0
      Do While i < image.Height ' i is incremented at the end
         ' Compression of the 16-line chunk starts here
         Dim j As Integer = 0
         Dim inBufferIndex As Integer = 0
         Do While (i + j) < image.Height AndAlso j < 16
            ' Get one line at time
            image.GetRow(i + j, inBuffer, inBufferIndex, lineBytes)

            ' Move to next line
            inBufferIndex += lineBytes

            j += 1
         Loop

         ' This is the main function that will do the actual Compression
         codecs.Compress(inBuffer, 0)
         i += 16
      Loop

      ' Reset the compression engine 
      codecs.StopCompress()

      ' Release the image and close the file
      image.Release()
      _compressStream.Close()

      ' Clean up
      codecs.Dispose()
   End Sub

   Private _compressStream As FileStream
   Private _compressBuffer As Byte()

   Private Function MyCodecsCompressDataCallback(ByVal width As Integer, ByVal height As Integer, ByVal bitsPerPixel As Integer, ByVal order As RasterByteOrder, ByVal viewPerspective As RasterViewPerspective, ByVal buffer As RasterNativeBuffer) As Boolean
      ' Write data to the file
      If _compressBuffer Is Nothing OrElse _compressBuffer.Length < buffer.Length Then
         _compressBuffer = New Byte(CType(buffer.Length, Integer) - 1) {}
      End If

      Marshal.Copy(buffer.Data, _compressBuffer, 0, CType(buffer.Length, Integer))

      _compressStream.Write(_compressBuffer, 0, CType(buffer.Length, Integer))

      Return True
   End Function

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class
C#Copy Code
public void CompressExample()
   {
      RasterCodecs codecs = new RasterCodecs();

      string srcFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp");
      string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Image1_CompressData.cmp");

      // Load the image to at 24-bits per pixel
      RasterImage image = codecs.Load(srcFileName, 24, CodecsLoadByteOrder.Bgr, 1, 1);
      if(image.ViewPerspective != RasterViewPerspective.TopLeft)
         image.ChangeViewPerspective(RasterViewPerspective.TopLeft);

      // Create the output file
      _compressStream = File.Create(destFileName);

      // Calculate the bytes per line in the input buffer, without padding 
      int lineBytes = image.Width * 3;

      // Allocate a buffer for the incoming uncompressed data. Note that we
      //  are compressing 16 lines at a time. You should always use multiples of 16
      byte[] inBuffer = new byte[16 * lineBytes];

      // Allocate an output buffer. This is where the compressed data will
      // go.  Note that this allocates 1024-byte packets. 
      byte[] outBuffer = new byte[1024];

      // Lock down the image
      image.Access();

      // Initialize the compression engine
      codecs.Options.Jpeg.Save.CmpQualityFactorPredefined = CodecsCmpQualityFactorPredefined.QualityAndSize;
      codecs.StartCompress(
         image.Width,
         image.Height,
         image.BitsPerPixel,
         image.Order,
         image.ViewPerspective,
         16 * lineBytes,
         outBuffer,
         0,
         outBuffer.Length,
         CodecsCompression.Cmp,
         MyCodecsCompressDataCallback);

      // Compress the data
      int i = 0;
      while(i < image.Height) // i is incremented at the end
      {
         // Compression of the 16-line chunk starts here
         int j = 0;
         int inBufferIndex = 0;
         while((i + j) < image.Height && j < 16)
         {
            // Get one line at time
            image.GetRow(i + j, inBuffer, inBufferIndex, lineBytes);

            // Move to next line
            inBufferIndex += lineBytes;

            j++;
         }

         // This is the main function that will do the actual Compression
         codecs.Compress(inBuffer, 0);
         i += 16;
      }

      // Reset the compression engine 
      codecs.StopCompress();

      // Release the image and close the file
      image.Release();
      _compressStream.Close();

      // Clean up
      codecs.Dispose();
   }

   FileStream _compressStream;
   byte[] _compressBuffer;

   bool MyCodecsCompressDataCallback(int width, int height, int bitsPerPixel, RasterByteOrder order, RasterViewPerspective viewPerspective, RasterNativeBuffer buffer)
   {
      // Write data to the file
      if(_compressBuffer == null || _compressBuffer.Length < buffer.Length)
         _compressBuffer = new byte[(int)buffer.Length];

      Marshal.Copy(buffer.Data, _compressBuffer, 0, (int)buffer.Length);

      _compressStream.Write(_compressBuffer, 0, (int)buffer.Length);

      return true;
   }

static class LEAD_VARS
{
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}
SilverlightCSharpCopy Code
SilverlightVBCopy Code

Remarks

This method initializes the buffered compression engine. The compression is then carried out using the Compress(Byte[],Int32) method. It is ended by the StopCompress method.

If order is set to to RasterByteOrder.Bgr and viewPerspective is RasterViewPerspective.TopLeft then the data that you put into the input buffer must be RasterByteOrder.Bgr and loaded from top left.

The compression process starts after the first call to Compress(Byte[],Int32). The callback is called when the output buffer is filled with compressed data or after completing the compression process. callback is responsible for emptying the output buffer - storing it, sending it, or doing other processing.

The following is a flow chart that shows the relationship of these methods:

Call StopCompress to end the compression process started by a call to StartCompress(Int32,Int32,Int32,RasterByteOrder,RasterViewPerspective,Int32,Byte[],Int32,Int32,CodecsCompression,CodecsCompressDataCallback).

The quality factor of the compressed data is obtained as follows:

Format Quality factor used
CodecsCompression.Cmp CodecsJpegSaveOptions.QualityFactor and CodecsJpegSaveOptions.CmpQualityFactorPredefined
CodecsCompression.Jpeg444 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.Jpeg422 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.Jpeg411 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.TifJpeg444 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.TifJpeg422 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.TifJpeg411 CodecsJpegSaveOptions.QualityFactor
CodecsCompression.Lead0 Not used
CodecsCompression.Lead1 Not used
CodecsCompression.TiffCcitt Not used
CodecsCompression.TiffCcittG3Fax1Dim Not used
CodecsCompression.TiffCcittG3Fax2Dim Not used
CodecsCompression.TiffCcittG4Fax Not used

This method does not support signed data images.

Requirements

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

See Also