CkPython Requires Chilkat v11.0.0+

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. CkPython

import sys
import chilkat

success = False

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

facSrc = chilkat.CkFileAccess()
facDest = chilkat.CkFileAccess()

#  Open a previously compressed file for decompressing.
#  See Compress Large File in Blocks

success = facSrc.OpenForRead("c:/temp/qa_output/compressedBmp.dat")
if (success == False):
    print(facSrc.lastErrorText())
    sys.exit()

#  If we compress in 32K chunks, find out how many blocks there will be.
blockSize = 32768
numBlocks = facSrc.GetNumBlocks(blockSize)

#  Open an output file for the decompressed data.
success = facDest.OpenForWrite("c:/temp/qa_output/decompressed.bmp")
if (success == False):
    print(facDest.lastErrorText())
    sys.exit()

compress = chilkat.CkCompression()
compress.put_Algorithm("deflate")

decompressedBytes = chilkat.CkByteData()
compressedBytes = chilkat.CkByteData()

#  Assuming numBlocks > 1
compress.put_FirstChunk(True)
compress.put_LastChunk(False)

i = 0
while i < numBlocks :
    success = facSrc.ReadBlock(i,blockSize,compressedBytes)

    success = compress.DecompressBytes(compressedBytes,decompressedBytes)
    facDest.FileWrite(decompressedBytes)

    i = i + 1

    compress.put_FirstChunk(False)
    if (i == (numBlocks - 1)):
        compress.put_LastChunk(True)

facSrc.FileClose()
facDest.FileClose()

print("Finished decompressing file.")