(Xojo Plugin) Compress Large Binary File in Blocks

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

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

// This example assumes 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 large binary file for reading.
Dim success As Boolean
success = facSrc.OpenForRead("qa_data/bmp/big.bmp")
If (success <> True) Then
    System.DebugLog(facSrc.LastErrorText)
    Return
End If

// If we compress in 64K chunks, find out how many blocks there will be.
Dim blockSize As Int32
blockSize = 65536
Dim numBlocks As Int32
numBlocks = facSrc.GetNumBlocks(blockSize)

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

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

Dim fileBytes As MemoryBlock
Dim compressedBytes As MemoryBlock

Dim i As Int32
i = 0
While i < numBlocks
    fileBytes = facSrc.ReadBlock(i,blockSize)
    If (i = 0) Then
        compressedBytes = compress.BeginCompressBytes(fileBytes)
    Else
        compressedBytes = compress.MoreCompressBytes(fileBytes)
    End If

    success = facDest.FileWrite(compressedBytes)

    i = i + 1
Wend

// At the very end, flush any remaining compressed bytes, if any.
compressedBytes = compress.EndCompressBytes()
success = facDest.FileWrite(compressedBytes)

facSrc.FileClose 
facDest.FileClose 

System.DebugLog("Finished compressing file.")