Delphi DLL Requires Chilkat v11.0.0+

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. Delphi DLL

var
success: Boolean;
facSrc: HCkFileAccess;
facDest: HCkFileAccess;
blockSize: Integer;
numBlocks: Integer;
compress: HCkCompression;
decompressedBytes: HCkByteData;
compressedBytes: HCkByteData;
i: Integer;

begin
success := False;

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

facSrc := CkFileAccess_Create();
facDest := CkFileAccess_Create();

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

success := CkFileAccess_OpenForRead(facSrc,'c:/temp/qa_output/compressedBmp.dat');
if (success = False) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(facSrc));
    Exit;
  end;

//  If we compress in 32K chunks, find out how many blocks there will be.
blockSize := 32768;
numBlocks := CkFileAccess_GetNumBlocks(facSrc,blockSize);

//  Open an output file for the decompressed data.
success := CkFileAccess_OpenForWrite(facDest,'c:/temp/qa_output/decompressed.bmp');
if (success = False) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(facDest));
    Exit;
  end;

compress := CkCompression_Create();
CkCompression_putAlgorithm(compress,'deflate');

decompressedBytes := CkByteData_Create();
compressedBytes := CkByteData_Create();

//  Assuming numBlocks > 1
CkCompression_putFirstChunk(compress,True);
CkCompression_putLastChunk(compress,False);

i := 0;
while i < numBlocks do
  begin
    success := CkFileAccess_ReadBlock(facSrc,i,blockSize,compressedBytes);

    success := CkCompression_DecompressBytes(compress,compressedBytes,decompressedBytes);
    CkFileAccess_FileWrite(facDest,decompressedBytes);

    i := i + 1;

    CkCompression_putFirstChunk(compress,False);
    if (i = (numBlocks - 1)) then
      begin
        CkCompression_putLastChunk(compress,True);
      end;
  end;

CkFileAccess_FileClose(facSrc);
CkFileAccess_FileClose(facDest);

Memo1.Lines.Add('Finished decompressing file.');

CkFileAccess_Dispose(facSrc);
CkFileAccess_Dispose(facDest);
CkCompression_Dispose(compress);
CkByteData_Dispose(decompressedBytes);
CkByteData_Dispose(compressedBytes);