Creating Compressed (Zipped) Folder using Delphi

Question

Can I create Windows XP's Compressed (Zipped) Folder using Delphi?

Answer 1

According to a thread in eggheadcafe, you can use CreateFile Function with FILE_FLAG_BACKUP_SEMANTICS to create a Compressed Folder.

For shell extensions route, take a look at Using Windows XP "Compressed Folder" shell extension to work with .zip files by Namespace Edanmo, which is written in VB.

I just found the similar question asked on C++. Take a look at Creating a ZIP file on Windows (XP/2003) in C/C++. I have a feeling the easiest route is buying ZipForge. See Zip a file in Delphi code sample.

Answer 2

A "zipped" folder in Windows is nothing more than a .ZIP file compressed using any standard zip library. Compressed folders are a different animal and require an NTFS disk format.

For the "Zip" file, I strongly suggest the Turbo Power Abbrevia, which is open source and works well. You might want to check this alternate site if your using Delphi 2009 as it might be a more recent copy.

If your wanting to use the compressed folders option, you will need to modify the directory flags on the directory handle. This will only impact NEW files added to that directory and will not automatically compress existing files. If you have an existing directory you are trying to compress, then rename each existing file, and load and save it back to the original name deleting the original file when complete with each one. Yozey had a good link to the MSDN documentation. Just remember that this only works with NTFS formatted disks, so you will need to add a check for that in your code.

Answer 3

If you are using Delphi X2, just use TZipFile from System.Zip:

To Zip a folder, use:

TZipFile.ZipDirectoryContents('ZipFile.zip', 'C:\Zip\this\right\now');

To Zip files, use:

Zip := TZipFile.Create;
try
  Zip.Open('ZipFile.zip', zmWrite);

  Zip.Add('FileToBeZipped.txt');
  Zip.Add('ThisWillBeCompressedAgainForSureAndBecomeSmaller.zip');
finally
  Zip.Free;
end

Answer 4

Take a look at these:

• File Compression
• FSCTL_SET_COMPRESSION

Answer 5

Take a look at this OpenSource SynZip unit. It's even faster for decompression than the default unit shipped with Delphi, and it will generate a smaller exe (crc tables are created at startup).

No external dll is needed. Works from Delphi 6 up to XE. No problem with Unicode version of Delphi. All in a single unit.

I just made some changes to handle Unicode file names inside Zip content, not only Win-Ansi charset but any Unicode chars. Feedback is welcome.

Answer 6

Some time ago, I've tried all of the Delphi compression libraries that I could find, and eventually I ended up using KaZip by Kiril Antonov.

My requirements were:

• Free;
• Open source;
• Native Delphi code;
• No external dependencies (dll, exe). My most important requirement;
• Small memory footprint;
• Easy to use;

I use it mainly to turn .kml files into .kmz, and it does that amazingly fast.

Here's an example of how I use it:

uses
  KaZip;

...

// replaces a .kml file with a .kmz file
procedure KmlToKmz(const aFileName: string);
var
  FS: TFileStream;
  KaZip:TKaZip;
  KmzFileName:TFileName;
begin
  KmzFileName := ChangeFileExt(aFileName, '.kmz');
  KaZip := TKaZip.Create(nil);
  try
    // create an empty zipfile with .kmz extension:
    FS := TFileStream.Create(KmzFileName, fmOpenReadWrite or FmCreate);
    try
      KaZip.CreateZip(FS);
    finally
      FS.Free;
    end;        

    KaZip.Open(KmzFileName); // Open the new .kmz zipfile
    KaZip.Entries.AddFile(aFileName); // add the .kml
    KaZip.Close; 
    DeleteFile(aFileName); // delete the .kml
  finally
    KaZip.Free;
  end;
end;