(Delphi DLL) Unzip Binary File to Stream

Demonstrates how to unzip a large binary file to a stream to allow the application to process the uncompressed bytes chunk by chunk.

Note: This example requires Chilkat v9.5.0.67 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, Zip, Stream, FileAccess, BinData, ZipEntry, Task;

...

procedure TForm1.Button1Click(Sender: TObject);
var
zip: HCkZip;
success: Boolean;
entry: HCkZipEntry;
dataStream: HCkStream;
unzipTask: HCkTask;
fac: HCkFileAccess;
bd: HCkBinData;

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

zip := CkZip_Create();

// First open a .zip.
success := CkZip_OpenZip(zip,'qa_data/zips/big.zip');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

// Get the entry to be unzipped to a stream..
entry := CkZip_GetEntryByIndex(zip,0);
if (CkZip_getLastMethodSuccess(zip) <> True) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

dataStream := CkStream_Create();

unzipTask := CkZipEntry_UnzipToStreamAsync(entry,dataStream);
if (CkZipEntry_getLastMethodSuccess(entry) <> True) then
  begin
    Memo1.Lines.Add(CkZipEntry__lastErrorText(entry));
    CkZipEntry_Dispose(entry);
    Exit;
  end;

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

// We'll read the uncompressed data chunk-by-chunk and write to an output file.
fac := CkFileAccess_Create();
success := CkFileAccess_OpenForWrite(fac,'qa_output/out.dat');
if (success <> True) then
  begin
    Memo1.Lines.Add(CkFileAccess__lastErrorText(fac));
    CkZipEntry_Dispose(entry);
    Exit;
  end;

// Read the stream.  (this is reading the unzipped file data)
bd := CkBinData_Create();
while CkStream_getEndOfStream(dataStream) <> True do
  begin
    // Get the next chunk of decompressed bytes.
    CkStream_ReadBd(dataStream,bd);
    // Do something with it..
    // In this simple example, we'll just write to the file.
    CkFileAccess_FileWriteBd(fac,bd,0,0);
    // Clear for the next read.
    CkBinData_Clear(bd);
  end;

CkFileAccess_FileClose(fac);

CkZipEntry_Dispose(entry);
CkTask_Dispose(unzipTask);
Memo1.Lines.Add('Success.');

CkZip_Dispose(zip);
CkStream_Dispose(dataStream);
CkFileAccess_Dispose(fac);
CkBinData_Dispose(bd);

end;