(Delphi ActiveX) Unzip One File to a Stream

Demonstrates how to unzip a particular file contained within a .zip archive to a Chilkat stream.

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
zip: TChilkatZip;
success: Integer;
entry: IChilkatZipEntry;
streamA: TChilkatStream;
streamB: TChilkatStream;
unzipTask: IChilkatTask;
sb: TChilkatStringBuilder;
streamC: TChilkatStream;
s: WideString;

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

zip := TChilkatZip.Create(Self);

// First open a .zip.
success := zip.OpenZip('qa_data/hamlet.zip');
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// Find the entry to be unzipped to a stream..
entry := zip.FirstMatchingEntry('*hamlet.xml');
if (zip.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// There are three ways we can unzip (inflate) to a stream.
// 
// 1) Set a sink file on the stream object and call UnzipToStream synchronously.
//    This unzips to the stream's sink (which is to simply unzip to a file in the filesystem).
// 
// 2) Create a stream object and call UnzipToStreamAsync.  This starts the unzip in a background
//    thread (after Task.Run is called).  Your application can then read the unzipped (inflated) file
//    directly from the stream.
// 
// 3) (not shown in this example) Unzip to a stream object that is the source of something else.
//    

// ----------------------------------------------------------------
// Case 1: Unzip to a file by setting the sink of streamA to a file.
streamA := TChilkatStream.Create(Self);
streamA.SinkFile := 'qa_output/hamletA.xml';

success := entry.UnzipToStream(streamA.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(entry.LastErrorText);

    Exit;
  end;

// Close the stream to close the output file.
success := streamA.WriteClose();

// ----------------------------------------------------------------
// Case 2a: Uzip to a stream asynchronously. 
streamB := TChilkatStream.Create(Self);

unzipTask := entry.UnzipToStreamAsync(streamB.ControlInterface);
if (entry.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(entry.LastErrorText);

    Exit;
  end;

// Start the background unzip thread.
unzipTask.Run();

// Read the stream.  (this is reading the unzipped file data)
sb := TChilkatStringBuilder.Create(Self);
while streamB.EndOfStream <> 1 do
  begin
    // Each call to ReadSb appends to the contents of sb.
    streamB.ReadSb(sb.ControlInterface);
  end;

sb.WriteFile('qa_output/hamletB.xml','utf-8',0);

Memo1.Lines.Add('Success.');

// ----------------------------------------------------------------
// Case 2b: Uzip to a stream asynchronously and emit output while reading. 
streamC := TChilkatStream.Create(Self);

unzipTask := entry.UnzipToStreamAsync(streamC.ControlInterface);
if (entry.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(entry.LastErrorText);

    Exit;
  end;

unzipTask.Run();

while streamC.EndOfStream <> 1 do
  begin
    s := streamC.ReadString();
    Memo1.Lines.Add(s);
  end;

Memo1.Lines.Add('Success.');
end;