(Delphi ActiveX) Transition from BeginCompressStringENC to FirstChunk/LastChunk

Provides instructions for replacing deprecated BeginCompressStringENC method calls with using FirstChunk/LastChunk properties.

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

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
success: Integer;
sbCompressedBase64: TChilkatStringBuilder;
compress: TChilkatCompression;
sbIndex: TChilkatStringBuilder;
i: Integer;
originalText: WideString;
bdCompressed: TChilkatBinData;
sbUncompressedChunk: TChilkatStringBuilder;

begin
success := 0;

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

sbCompressedBase64 := TChilkatStringBuilder.Create(Self);

compress := TChilkatCompression.Create(Self);
compress.Algorithm := 'deflate';
compress.Charset := 'utf-8';
compress.EncodingMode := 'base64';

sbIndex := TChilkatStringBuilder.Create(Self);

// ----------------------------------------------------------------------------------
// This is the deprecated way of compressing in chunks using Begin/More/End methods..
// ----------------------------------------------------------------------------------

for i := 0 to 24 do
  begin
    // Note: It is possible (and normal) for a BeginCompress* or MoreCompress* method to return
    // an empty string (or 0 bytes).  When this happens, the input data is not lost.  It will be flushed
    // in a subsequent call.
    sbIndex.Clear();
    sbIndex.AppendInt(i);
    if (i = 0) then
      begin
        sbCompressedBase64.Append(compress.BeginCompressStringENC(sbIndex.GetAsString()));
      end
    else
      begin
        sbCompressedBase64.Append(compress.MoreCompressStringENC(sbIndex.GetAsString()));
      end;
    sbCompressedBase64.Append(compress.MoreCompressStringENC(': This is a line of data to be compressed...' + #13#10));
  end;

// Flush any remaining output.
sbCompressedBase64.Append(compress.EndCompressStringENC());

Memo1.Lines.Add('The base64 encoded compressed text:');
Memo1.Lines.Add(sbCompressedBase64.GetAsString());

// Decompress in one call:
originalText := compress.DecompressStringENC(sbCompressedBase64.GetAsString());
Memo1.Lines.Add(originalText);

// ----------------------------------------------------------------------------------
// This is new way of compressing in chunks using FirstChunk and LastChunk properties
// ----------------------------------------------------------------------------------

sbCompressedBase64.Clear();

compress.FirstChunk := 1;
compress.LastChunk := 0;

bdCompressed := TChilkatBinData.Create(Self);
sbUncompressedChunk := TChilkatStringBuilder.Create(Self);

for i := 0 to 24 do
  begin
    if (i = 24) then
      begin
        compress.LastChunk := 1;
      end;

    sbUncompressedChunk.Clear();
    sbUncompressedChunk.AppendInt(i);
    sbUncompressedChunk.Append(': This is a line of data to be compressed...' + #13#10);

    compress.CompressSb(sbUncompressedChunk.ControlInterface,bdCompressed.ControlInterface);

    compress.FirstChunk := 0;
  end;

Memo1.Lines.Add('The base64 encoded compressed text:');
Memo1.Lines.Add(bdCompressed.GetEncoded('base64'));

// Decompress in one call:
originalText := compress.DecompressStringENC(bdCompressed.GetEncoded('base64'));
Memo1.Lines.Add(originalText);
end;