(CkPython) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux

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.")