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[wxWidgets.git] / docs / doxygen / overviews / filesystem.h

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// Name:        filesystem.h
// Purpose:     topic overview
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/*!

 @page overview_fs wxFileSystem overview

 The wxHTML library uses a @b virtual file systems mechanism
 similar to the one used in Midnight Commander, Dos Navigator,
 FAR or almost any modern file manager. It allows the user to access
 data stored in archives as if they were ordinary files. On-the-fly
 generated files that exist only in memory are also supported.

 @li @ref overview_fs_classes
 @li @ref overview_fs_locations
 @li @ref overview_fs_combined
 @li @ref overview_fs_wxhtmlfs
 @li @ref overview_fs_init


 <hr>


 @section overview_fs_classes Classes

 Three classes are used in order to provide virtual file systems mechanism:

 @li The wxFSFile class provides information
     about opened file (name, input stream, mime type and anchor).
 @li The wxFileSystem class is the interface.
     Its main methods are ChangePathTo() and OpenFile(). This class
     is most often used by the end user.
 @li The wxFileSystemHandler is the core
     of virtual file systems mechanism. You can derive your own handler and pass 
     it to the VFS mechanism. You can derive your own handler and pass it to
     wxFileSystem's AddHandler() method. In the new handler you only need to
     override the OpenFile() and CanOpen() methods.


 @section overview_fs_locations Locations

 Locations (aka filenames aka addresses) are constructed from four parts:

 @li @b protocol - handler can recognize if it is able to open a
     file by checking its protocol. Examples are "http", "file" or "ftp".
 @li <b>right location</b> - is the name of file within the protocol.
     In "http://www.wxwidgets.org/index.html" the right location is "//www.wxwidgets.org/index.html".
 @li @b anchor - an anchor is optional and is usually not present.
     In "index.htm#chapter2" the anchor is "chapter2".
 @li <b>left location</b> - this is usually an empty string.
     It is used by 'local' protocols such as ZIP.
     See Combined Protocols paragraph for details.


 @section overview_fs_combined Combined Protocols

 The left location precedes the protocol in the URL string.

 It is not used by global protocols like HTTP but it becomes handy when nesting
 protocols - for example you may want to access files in a ZIP archive:
 file:archives/cpp_doc.zip#zip:reference/fopen.htm#syntax
 In this example, the protocol is "zip", right location is
 "reference/fopen.htm", anchor is "syntax" and left location
 is "file:archives/cpp_doc.zip".

 There are @b two protocols used in this example: "zip" and "file".


 @section overview_fs_wxhtmlfs File Systems Included in wxHTML

 The following virtual file system handlers are part of wxWidgets so far:

 @li @b wxArchiveFSHandler:
     A handler for archives such as zip
     and tar. Include file is wx/fs_arc.h. URLs examples:
     "archive.zip#zip:filename", "archive.tar.gz#gzip:#tar:filename".
 @li @b wxFilterFSHandler:
     A handler for compression schemes such
     as gzip. Header is wx/fs_filter.h. URLs are in the form, e.g.:
     "document.ps.gz#gzip:".
 @li @b wxInternetFSHandler:
     A handler for accessing documents
     via HTTP or FTP protocols. Include file is wx/fs_inet.h.
 @li @b wxMemoryFSHandler:
     This handler allows you to access
     data stored in memory (such as bitmaps) as if they were regular files.
     See wxMemoryFSHandler for details.
     Include file is wx/fs_mem.h. URL is prefixed with memory:, e.g.
     "memory:myfile.htm"

 In addition, wxFileSystem itself can access local files.


 @section overview_fs_init Initializing file system handlers

 Use wxFileSystem::AddHandler to initialize a handler, for example:

 @code
 #include <wx/fs_mem.h>

 ...

 bool MyApp::OnInit()
 {
     wxFileSystem::AddHandler(new wxMemoryFSHandler);
 ...
 }
 @endcode

*/