docs/doxygen/overviews/filesystem.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        filesystem.h
   3 // Purpose:     topic overview
   4 // Author:      wxWidgets team
   5 // Licence:     wxWindows licence
   6 /////////////////////////////////////////////////////////////////////////////
   7
   8 /**
   9
  10 @page overview_fs wxFileSystem Overview
  11
  12 @tableofcontents
  13
  14 The wxHTML library uses a @b virtual file system mechanism similar to the one
  15 used in Midnight Commander, Dos Navigator, FAR or almost any modern file
  16 manager. It allows the user to access data stored in archives as if they were
  17 ordinary files. On-the-fly generated files that exist only in memory are also
  18 supported.
  19
  20
  21
  22 @section overview_fs_classes Classes
  23
  24 Three classes are used in order to provide virtual file systems mechanism:
  25
  26 @li The wxFSFile class provides information
  27     about opened file (name, input stream, mime type and anchor).
  28 @li The wxFileSystem class is the interface.
  29     Its main methods are ChangePathTo() and OpenFile(). This class
  30     is most often used by the end user.
  31 @li The wxFileSystemHandler is the core
  32     of virtual file systems mechanism. You can derive your own handler and pass
  33     it to the VFS mechanism. You can derive your own handler and pass it to
  34     wxFileSystem's AddHandler() method. In the new handler you only need to
  35     override the OpenFile() and CanOpen() methods.
  36
  37
  38 @section overview_fs_locations Locations
  39
  40 Locations (aka filenames aka addresses) are constructed from four parts:
  41
  42 @li @b protocol - handler can recognize if it is able to open a
  43     file by checking its protocol. Examples are "http", "file" or "ftp".
  44 @li <b>right location</b> - is the name of file within the protocol.
  45     In "http://www.wxwidgets.org/index.html" the right location is "//www.wxwidgets.org/index.html".
  46 @li @b anchor - an anchor is optional and is usually not present.
  47     In "index.htm#chapter2" the anchor is "chapter2".
  48 @li <b>left location</b> - this is usually an empty string.
  49     It is used by 'local' protocols such as ZIP.
  50     See Combined Protocols paragraph for details.
  51
  52
  53 @section overview_fs_combined Combined Protocols
  54
  55 The left location precedes the protocol in the URL string.
  56
  57 It is not used by global protocols like HTTP but it becomes handy when nesting
  58 protocols - for example you may want to access files in a ZIP archive:
  59 file:archives/cpp_doc.zip#zip:reference/fopen.htm#syntax
  60 In this example, the protocol is "zip", right location is
  61 "reference/fopen.htm", anchor is "syntax" and left location
  62 is "file:archives/cpp_doc.zip".
  63
  64 There are @b two protocols used in this example: "zip" and "file".
  65
  66
  67 @section overview_fs_wxhtmlfs File Systems Included in wxHTML
  68
  69 The following virtual file system handlers are part of wxWidgets so far:
  70
  71 @li @b wxArchiveFSHandler:
  72     A handler for archives such as zip
  73     and tar. Include file is wx/fs_arc.h. URLs examples:
  74     "archive.zip#zip:filename", "archive.tar.gz#gzip:#tar:filename".
  75 @li @b wxFilterFSHandler:
  76     A handler for compression schemes such
  77     as gzip. Header is wx/fs_filter.h. URLs are in the form, e.g.:
  78     "document.ps.gz#gzip:".
  79 @li @b wxInternetFSHandler:
  80     A handler for accessing documents
  81     via HTTP or FTP protocols. Include file is wx/fs_inet.h.
  82 @li @b wxMemoryFSHandler:
  83     This handler allows you to access
  84     data stored in memory (such as bitmaps) as if they were regular files.
  85     See wxMemoryFSHandler for details.
  86     Include file is wx/fs_mem.h. URL is prefixed with memory:, e.g.
  87     "memory:myfile.htm"
  88
  89 In addition, wxFileSystem itself can access local files.
  90
  91
  92 @section overview_fs_init Initializing file system handlers
  93
  94 Use wxFileSystem::AddHandler to initialize a handler, for example:
  95
  96 @code
  97 #include <wx/fs_mem.h>
  98
  99 ...
 100
 101 bool MyApp::OnInit()
 102 {
 103     wxFileSystem::AddHandler(new wxMemoryFSHandler);
 104 ...
 105 }
 106 @endcode
 107
 108 */