(Delphi ActiveX) Chilkat Zip API Concepts

This example helps clarify some common misconceptions w/ using the Chilkat Zip API.

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;
saveExtraPath: Integer;
entry: IChilkatZipEntry;
i: Integer;
n: Integer;

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

zip := TChilkatZip.Create(Self);

// To clarify some concepts, this example will create a new .zip containing 2 files.

// The NewZip method is called to initialize the zip object to a new and empty state.
// It does not actually create the .zip file.  It simply intializes the object.
// if the zip object did not contain anything previously, then this method could be skipped
// altogether.  It has the side-effect of setting the zip.FileName property.
success := zip.NewZip('test.zip');
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// The FileName property should now contain "test.zip".  This is the name of the .zip
// that is written when WriteZip or WriteZipAndClose is called.
Memo1.Lines.Add('zip filename = ' + zip.FileName);

// When a file is "appended" to the zip object, we are really just appending a reference
// to the file in the filesystem.  A "zip entry" is added to the zip object and this entry
// can be one of several types.  It can point to a file.  It can contain uncompressed binary
// or text data, it can point to an entry in the already-opened zip (if we had called OpenZip 
// instead), etc.  

// Now.. add a reference to a single file by calling AppendOneFileOrDir
// Note: On Windows, forward slashes are equivalent to backslashes
saveExtraPath := 0;
success := zip.AppendOneFileOrDir('/temp/abc123/HelloWorld123.txt',saveExtraPath);
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// We now have a zip object with one entry, which points to the file /temp/abc123/HelloWorld123.txt
// If desired, we could change the filename of the zip entry so that when the zip is written,
// the file has a different name:
entry := zip.GetEntryByIndex(0);
entry.FileName := 'helloWorld.txt';

// When the zip is actually written, the entry's data will stream from /temp/abc123/HelloWorld123.txt
// and be compressed into an entry within the .zip having the filename "helloWorld.txt"

// Now add another entry, this time from a string containing the file content:
entry := zip.AppendString2('HelloWorld2.txt','hello world!','utf-8');

// Examine the entries in the zip so far..
// Each entry can be one of the following types:

// 0 -- Mapped Entry: An entry in an existing Zip file.
// 1 -- File Entry: A file not yet in memory, but referenced. 
//      These entries are added by calling AppendFiles, AppendFilesEx, AppendOneFileOrDir, etc.
// 2 -- Data Entry: An entry containing uncompressed data from memory. 
//      These entries are added by calling AppendData, AppendString, etc.
// 3 -- Null Entry: An entry that no longer exists in the .zip.
// 4 -- New Directory Entry: A directory entry added by calling AppendNewDir. 

n := zip.NumEntries;
for i := 0 to n - 1 do
  begin

    entry := zip.GetEntryByIndex(i);
    Memo1.Lines.Add(entry.FileName + ', type=' + IntToStr(entry.EntryType));

  end;

// Write the "test.zip" file.
success := zip.WriteZip();
if (success <> 1) then
  begin
    Memo1.Lines.Add(zip.LastErrorText);
    Exit;
  end;

// Our zip object still contains 2 entries, but now they point to the entries within the 
// test.zip  (We called WriteZip, which writes the .zip but does not close it.  Instead,
// the entries of the zip object are updated to become "mapped" entries.
// For example:

n := zip.NumEntries;
for i := 0 to n - 1 do
  begin

    entry := zip.GetEntryByIndex(i);
    Memo1.Lines.Add(entry.FileName + ', type=' + IntToStr(entry.EntryType));

  end;

// Finally, close the zip
zip.CloseZip();
end;