(Delphi ActiveX) Compress Large Binary File in Blocks

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

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

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
facSrc: TCkFileAccess;
facDest: TCkFileAccess;
success: Integer;
blockSize: Integer;
numBlocks: Integer;
compress: TChilkatCompression;
fileBytes: Array of Byte;
compressedBytes: Array of Byte;
i: Integer;

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

facSrc := TCkFileAccess.Create(Self);
facDest := TCkFileAccess.Create(Self);

// Open a large binary file for reading.
success := facSrc.OpenForRead('qa_data/bmp/big.bmp');
if (success <> 1) then
  begin
    Memo1.Lines.Add(facSrc.LastErrorText);
    Exit;
  end;

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

// Open an output file for the compressed data.
success := facDest.OpenForWrite('qa_data/bmp/compressedBmp.dat');
if (success <> 1) then
  begin
    Memo1.Lines.Add(facDest.LastErrorText);
    Exit;
  end;

compress := TChilkatCompression.Create(Self);
compress.Algorithm := 'deflate';

i := 0;
while i < numBlocks do
  begin
    fileBytes := facSrc.ReadBlock(i,blockSize);
    if (i = 0) then
      begin
        compressedBytes := compress.BeginCompressBytes(fileBytes);
      end
    else
      begin
        compressedBytes := compress.MoreCompressBytes(fileBytes);
      end;

    facDest.FileWrite(compressedBytes);

    i := i + 1;
  end;

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

facSrc.FileClose();
facDest.FileClose();

Memo1.Lines.Add('Finished compressing file.');
end;