7a8b9bd950
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@18219 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
92 lines
3.4 KiB
TeX
92 lines
3.4 KiB
TeX
\section{wxFileSystem}\label{fs}
|
|
|
|
The wxHTML library uses a {\bf 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.
|
|
|
|
\wxheading{Classes}
|
|
|
|
Three classes are used in order to provide virtual file systems mechanism:
|
|
|
|
\begin{itemize}\itemsep=0pt
|
|
\item The \helpref{wxFSFile}{wxfsfile} class provides information
|
|
about opened file (name, input stream, mime type and anchor).
|
|
\item The \helpref{wxFileSystem}{wxfilesystem} class is the interface.
|
|
Its main methods are ChangePathTo() and OpenFile(). This class
|
|
is most often used by the end user.
|
|
\item The \helpref{wxFileSystemHandler}{wxfilesystemhandler} is the core
|
|
of virtual file systems mechanism. You can derive your own handler and pass it to
|
|
of 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.
|
|
\end{itemize}
|
|
|
|
\wxheading{Locations}
|
|
|
|
Locations (aka filenames aka addresses) are constructed from four parts:
|
|
|
|
\begin{itemize}\itemsep=0pt
|
|
\item {\bf protocol} - handler can recognize if it is able to open a
|
|
file by checking its protocol. Examples are "http", "file" or "ftp".
|
|
\item {\bf right location} - is the name of file within the protocol.
|
|
In "http://www.wxwindows.org/index.html" the right location is "//www.wxwindows.org/index.html".
|
|
\item {\bf anchor} - an anchor is optional and is usually not present.
|
|
In "index.htm\#chapter2" the anchor is "chapter2".
|
|
\item {\bf left location} - this is usually an empty string.
|
|
It is used by 'local' protocols such as ZIP.
|
|
See Combined Protocols paragraph for details.
|
|
\end{itemize}
|
|
|
|
\wxheading{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 {\bf two} protocols used in this example: "zip" and "file".
|
|
|
|
\wxheading{File Systems Included in wxHTML}
|
|
|
|
The following virtual file system handlers are part of wxWindows so far:
|
|
|
|
\begin{twocollist}
|
|
\twocolitem{{\bf wxInternetFSHandler}}{A handler for accessing documents
|
|
via HTTP or FTP protocols. Include file is <wx/fs\_inet.h>.}
|
|
\twocolitem{{\bf wxZipFSHandler}}{A handler for ZIP archives.
|
|
Include file is <wx/fs\_zip.h>. URL is in form "archive.zip\#zip:filename".}
|
|
\twocolitem{{\bf wxMemoryFSHandler}}{This handler allows you to access
|
|
data stored in memory (such as bitmaps) as if they were regular files.
|
|
See \helpref{wxMemoryFSHandler documentation}{wxmemoryfshandler} for details.
|
|
Include file is <wx/fs\_mem.h>. URL is prefixed with memory:, e.g.
|
|
"memory:myfile.htm"}
|
|
\end{twocollist}
|
|
|
|
In addition, wxFileSystem itself can access local files.
|
|
|
|
|
|
\wxheading{Initializing file system handlers}
|
|
|
|
Use \helpref{wxFileSystem::AddHandler}{wxfilesystemaddhandler} to initialize
|
|
a handler, for example:
|
|
|
|
\begin{verbatim}
|
|
#include <wx/fs_mem.h>
|
|
|
|
...
|
|
|
|
bool MyApp::OnInit()
|
|
{
|
|
wxFileSystem::AddHandler(new wxMemoryFSHandler);
|
|
...
|
|
}
|
|
\end{verbatim}
|
|
|