(Chilkat2-Python) Decompress Large Binary File in Blocks

Decompresses a large binary file in blocks. This example uses BeginDecompressBytes, MoreDecompressBytes, and EndDecompressBytes.

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import sys
import chilkat2

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

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

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

success = facSrc.OpenForRead("qa_data/bmp/compressedBmp.dat")
if (success != True):
    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("qa_output/decompressed.bmp")
if (success != True):
    print(facDest.LastErrorText)
    sys.exit()

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

i = 0
while i < numBlocks :
    # compressedBytes is a memoryview
    compressedBytes = facSrc.ReadBlock(i,blockSize)
    if (i == 0):
        # decompressedBytes is a memoryview
        decompressedBytes = compress.BeginDecompressBytes(compressedBytes)
    else:
        # decompressedBytes is a memoryview
        decompressedBytes = compress.MoreDecompressBytes(compressedBytes)

    facDest.FileWrite(decompressedBytes)

    i = i + 1

# At the very end, flush any remaining decompressed bytes, if any.
# decompressedBytes is a memoryview
decompressedBytes = compress.EndDecompressBytes()
facDest.FileWrite(decompressedBytes)

facSrc.FileClose()
facDest.FileClose()

print("Finished decompressing file.")