(Chilkat2-Python) Compress Large Binary File in Blocks

Compresses a large binary file in blocks. This example uses BeginCompressBytes, MoreCompressBytes, and EndCompressBytes.

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import sys
import chilkat2

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

facSrc = chilkat2.FileAccess()
facDest = chilkat2.FileAccess()

# Open a large binary file for reading.
success = facSrc.OpenForRead("qa_data/bmp/big.bmp")
if (success != True):
    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("qa_data/bmp/compressedBmp.dat")
if (success != True):
    print(facDest.LastErrorText)
    sys.exit()

compress = chilkat2.Compression()
compress.Algorithm = "deflate"

i = 0
while i < numBlocks :
    # fileBytes is a memoryview
    fileBytes = facSrc.ReadBlock(i,blockSize)
    if (i == 0):
        # compressedBytes is a memoryview
        compressedBytes = compress.BeginCompressBytes(fileBytes)
    else:
        # compressedBytes is a memoryview
        compressedBytes = compress.MoreCompressBytes(fileBytes)

    facDest.FileWrite(compressedBytes)

    i = i + 1

# At the very end, flush any remaining compressed bytes, if any.
# compressedBytes is a memoryview
compressedBytes = compress.EndCompressBytes()
facDest.FileWrite(compressedBytes)

facSrc.FileClose()
facDest.FileClose()

print("Finished compressing file.")