docs/latex/wx/fs.tex

   1 \section{File Systems}\label{fs}
   2
   3 The wxHTML library uses a {\bf virtual file systems} mechanism
   4 similar to the one used in Midnight Commander, Dos Navigator,
   5 FAR or almost any modern file manager. (Do you remember? You can
   6 press enter on ZIP file and its contents is displayed as if it
   7 were a local directory...)
   8
   9 \wxheading{Classes}
  10
  11 Three classes are used in order to provide full VFS:
  12
  13 \begin{itemize}
  14 \item The \helpref{wxFSFile}{wxfsfile} class provides information
  15 on opened file (name, input stream, mime type and anchor).
  16
  17 \item The \helpref{wxFileSystem}{wxfilesystem} class is the interface.
  18 Its main methods are ChangePathTo() and OpenFile(). This class
  19 is most often used by the end user.
  20
  21 \item The \helpref{wxFileSystemHandler}{wxfilesystemhandler} is the core
  22 if VFS mechanism. You can derive your own handler and pass it to
  23 wxFileSystem's AddHandler() method. In the new handler you only need to
  24 overwrite OpenFile() and CanOpen() methods.
  25 \end{itemize}
  26
  27 \wxheading{Locations}
  28
  29 Locations (aka filenames aka addresses) are constructed from 4 parts:
  30
  31 \begin{itemize}
  32 \item {\bf protocol} - handler can recognize if it is able to open a
  33 file by checking its protocol. Examples are "http", "file" or "ftp".
  34
  35 \item {\bf right location} - is the name of file within the protocol.
  36 In "http://www.wxwindows.org/index.html" the right location is "//www.wxwindows.org/index.html".
  37
  38 \item {\bf anchor} - anchor is optional and is usually not present.
  39 In "index.htm\#chapter2" the anchor is "chapter2".
  40
  41 \item {\bf left location} - this is usually an empty string.
  42 It is used by 'local' protocols such as ZIP.
  43 See Combined Protocols paragraph for details.
  44 \end{itemize}
  45
  46 \wxheading{Combined Protocols}
  47
  48 Left location pretends protocol in URL string.
  49 It's not used by global protocols like HTTP but it's used
  50 by local ones - for example you can see this address:
  51
  52 file:archives/cpp\_doc.zip\#zip:reference/fopen.htm\#syntax
  53
  54 In this example, protocol is "zip", left location is
  55 "reference/fopen.htm", anchor is "syntax" and right location
  56 is "file:archives/cpp_doc.zip". It is used by zip handler
  57 to determine in what file this particular zip VFS is stored.
  58
  59 In fact there are two protocols used in this example: zip and file.
  60 You can construct even more complicated addresses like this one:
  61
  62 http://www.archives.org/myarchive.zip\#zip:local/docs/cpp/stdio.zip\#zip:index.htm
  63
  64 In this example you access zip VFS stdio.zip stored in another zip (myarchive.zip)
  65 which is at WWW.
  66
  67 \wxheading{File Systems Included in wxHTML}
  68
  69 \begin{enumerate}
  70 \item Local files
  71 \item HTTP protocol
  72 \item FTP protocol
  73 \item .ZIP archives
  74 \end{enumerate}
  75