(Xojo Plugin) Decompress Large Binary File in Blocks

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

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim facSrc As New Chilkat.FileAccess
Dim facDest As New Chilkat.FileAccess

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

Dim success As Boolean
success = facSrc.OpenForRead("qa_data/bmp/compressedBmp.dat")
If (success <> True) Then
    System.DebugLog(facSrc.LastErrorText)
    Return
End If

// If we compress in 32K chunks, find out how many blocks there will be.
Dim blockSize As Int32
blockSize = 32768
Dim numBlocks As Int32
numBlocks = facSrc.GetNumBlocks(blockSize)

// Open an output file for the decompressed data.
success = facDest.OpenForWrite("qa_output/decompressed.bmp")
If (success <> True) Then
    System.DebugLog(facDest.LastErrorText)
    Return
End If

Dim compress As New Chilkat.Compression
compress.Algorithm = "deflate"

Dim decompressedBytes As MemoryBlock
Dim compressedBytes As MemoryBlock

Dim i As Int32
i = 0
While i < numBlocks
    compressedBytes = facSrc.ReadBlock(i,blockSize)
    If (i = 0) Then
        decompressedBytes = compress.BeginDecompressBytes(compressedBytes)
    Else
        decompressedBytes = compress.MoreDecompressBytes(compressedBytes)
    End If

    success = facDest.FileWrite(decompressedBytes)

    i = i + 1
Wend

// At the very end, flush any remaining decompressed bytes, if any.
decompressedBytes = compress.EndDecompressBytes()
success = facDest.FileWrite(decompressedBytes)

facSrc.FileClose 
facDest.FileClose 

System.DebugLog("Finished decompressing file.")