(CkPython) Compress Large Binary File in Blocks

Compresses a large binary file in blocks.

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

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import sys
import chilkat

success = False

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

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

# Open a large binary file for reading.
success = facSrc.OpenForRead("qa_data/bmp/big.bmp")
if (success == False):
    print(facSrc.lastErrorText())
    sys.exit()

# If we compress in 64K chunks, find out how many blocks there will be.
blockSize = 65536
numBlocks = facSrc.GetNumBlocks(blockSize)

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

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

fileBytes = 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,fileBytes)
    success = compress.CompressBytes(fileBytes,compressedBytes)

    facDest.FileWrite(compressedBytes)

    i = i + 1

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

facSrc.FileClose()
facDest.FileClose()

print("Finished compressing file.")