(Delphi DLL) 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 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, StringBuilder, BinData, Compression;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sbCompressedBase64: HCkStringBuilder;
compress: HCkCompression;
sbIndex: HCkStringBuilder;
i: Integer;
originalText: PWideChar;
bdCompressed: HCkBinData;
sbUncompressedChunk: HCkStringBuilder;

begin
success := False;

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

sbCompressedBase64 := CkStringBuilder_Create();

compress := CkCompression_Create();
CkCompression_putAlgorithm(compress,'deflate');
CkCompression_putCharset(compress,'utf-8');
CkCompression_putEncodingMode(compress,'base64');

sbIndex := CkStringBuilder_Create();

// ----------------------------------------------------------------------------------
// 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.
    CkStringBuilder_Clear(sbIndex);
    CkStringBuilder_AppendInt(sbIndex,i);
    if (i = 0) then
      begin
        CkStringBuilder_Append(sbCompressedBase64,CkCompression__beginCompressStringENC(compress,CkStringBuilder__getAsString(sbIndex)));
      end
    else
      begin
        CkStringBuilder_Append(sbCompressedBase64,CkCompression__moreCompressStringENC(compress,CkStringBuilder__getAsString(sbIndex)));
      end;
    CkStringBuilder_Append(sbCompressedBase64,CkCompression__moreCompressStringENC(compress,': This is a line of data to be compressed...' + #13#10));
  end;

// Flush any remaining output.
CkStringBuilder_Append(sbCompressedBase64,CkCompression__endCompressStringENC(compress));

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

// Decompress in one call:
originalText := CkCompression__decompressStringENC(compress,CkStringBuilder__getAsString(sbCompressedBase64));
Memo1.Lines.Add(originalText);

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

CkStringBuilder_Clear(sbCompressedBase64);

CkCompression_putFirstChunk(compress,True);
CkCompression_putLastChunk(compress,False);

bdCompressed := CkBinData_Create();
sbUncompressedChunk := CkStringBuilder_Create();

for i := 0 to 24 do
  begin
    if (i = 24) then
      begin
        CkCompression_putLastChunk(compress,True);
      end;

    CkStringBuilder_Clear(sbUncompressedChunk);
    CkStringBuilder_AppendInt(sbUncompressedChunk,i);
    CkStringBuilder_Append(sbUncompressedChunk,': This is a line of data to be compressed...' + #13#10);

    CkCompression_CompressSb(compress,sbUncompressedChunk,bdCompressed);

    CkCompression_putFirstChunk(compress,False);
  end;

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

// Decompress in one call:
originalText := CkCompression__decompressStringENC(compress,CkBinData__getEncoded(bdCompressed,'base64'));
Memo1.Lines.Add(originalText);

CkStringBuilder_Dispose(sbCompressedBase64);
CkCompression_Dispose(compress);
CkStringBuilder_Dispose(sbIndex);
CkBinData_Dispose(bdCompressed);
CkStringBuilder_Dispose(sbUncompressedChunk);

end;