(Delphi DLL) Compress Large Binary File in Blocks

Compresses a large binary file in blocks.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, FileAccess, CkByteData, Compression;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
facSrc: HCkFileAccess;
facDest: HCkFileAccess;
blockSize: Integer;
numBlocks: Integer;
compress: HCkCompression;
fileBytes: HCkByteData;
compressedBytes: HCkByteData;
i: Integer;

begin
success := False;

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

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

// Open a large binary file for reading.
success := CkFileAccess_OpenForRead(facSrc,'qa_data/bmp/big.bmp');
if (success = False) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(facSrc));
    Exit;
  end;

// If we compress in 64K chunks, find out how many blocks there will be.
blockSize := 65536;
numBlocks := CkFileAccess_GetNumBlocks(facSrc,blockSize);

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

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

fileBytes := 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,fileBytes);
    success := CkCompression_CompressBytes(compress,fileBytes,compressedBytes);

    CkFileAccess_FileWrite(facDest,compressedBytes);

    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 compressing file.');

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

end;