aa0ff209bc
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42805 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
96 lines
3.6 KiB
TeX
96 lines
3.6 KiB
TeX
\section{wxFileSystem}\label{fs}
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The wxHTML library uses a {\bf virtual file systems} mechanism
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similar to the one used in Midnight Commander, Dos Navigator,
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FAR or almost any modern file manager. It allows the user to access
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data stored in archives as if they were ordinary files. On-the-fly
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generated files that exist only in memory are also supported.
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\wxheading{Classes}
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Three classes are used in order to provide virtual file systems mechanism:
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\begin{itemize}\itemsep=0pt
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\item The \helpref{wxFSFile}{wxfsfile} class provides information
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about opened file (name, input stream, mime type and anchor).
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\item The \helpref{wxFileSystem}{wxfilesystem} class is the interface.
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Its main methods are ChangePathTo() and OpenFile(). This class
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is most often used by the end user.
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\item The \helpref{wxFileSystemHandler}{wxfilesystemhandler} is the core
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of virtual file systems mechanism. You can derive your own handler and pass it to
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the VFS mechanism. You can derive your own handler and pass it to
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wxFileSystem's AddHandler() method. In the new handler you only need to
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override the OpenFile() and CanOpen() methods.
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\end{itemize}
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\wxheading{Locations}
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Locations (aka filenames aka addresses) are constructed from four parts:
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\begin{itemize}\itemsep=0pt
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\item {\bf protocol} - handler can recognize if it is able to open a
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file by checking its protocol. Examples are "http", "file" or "ftp".
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\item {\bf right location} - is the name of file within the protocol.
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In "http://www.wxwidgets.org/index.html" the right location is "//www.wxwidgets.org/index.html".
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\item {\bf anchor} - an anchor is optional and is usually not present.
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In "index.htm\#chapter2" the anchor is "chapter2".
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\item {\bf left location} - this is usually an empty string.
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It is used by 'local' protocols such as ZIP.
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See Combined Protocols paragraph for details.
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\end{itemize}
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\wxheading{Combined Protocols}
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The left location precedes the protocol in the URL string.
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It is not used by global protocols like HTTP but it becomes handy when nesting
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protocols - for example you may want to access files in a ZIP archive:
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file:archives/cpp\_doc.zip\#zip:reference/fopen.htm\#syntax
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In this example, the protocol is "zip", right location is
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"reference/fopen.htm", anchor is "syntax" and left location
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is "file:archives/cpp\_doc.zip".
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There are {\bf two} protocols used in this example: "zip" and "file".
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\wxheading{File Systems Included in wxHTML}
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The following virtual file system handlers are part of wxWidgets so far:
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\begin{twocollist}
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\twocolitem{{\bf wxArchiveFSHandler}}{A handler for archives such as zip
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and tar. Include file is <wx/fs\_arc.h>. URLs examples:
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"archive.zip\#zip:filename", "archive.tar.gz\#gzip:\#tar:filename".}
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\twocolitem{{\bf wxFilterFSHandler}}{A handler for compression schemes such
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as gzip. Header is <wx/fs\_filter.h>. URLs are in the form, e.g.:
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"document.ps.gz\#gzip:".}
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\twocolitem{{\bf wxInternetFSHandler}}{A handler for accessing documents
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via HTTP or FTP protocols. Include file is <wx/fs\_inet.h>.}
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\twocolitem{{\bf wxMemoryFSHandler}}{This handler allows you to access
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data stored in memory (such as bitmaps) as if they were regular files.
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See \helpref{wxMemoryFSHandler documentation}{wxmemoryfshandler} for details.
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Include file is <wx/fs\_mem.h>. URL is prefixed with memory:, e.g.
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"memory:myfile.htm"}
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\end{twocollist}
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In addition, wxFileSystem itself can access local files.
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\wxheading{Initializing file system handlers}
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Use \helpref{wxFileSystem::AddHandler}{wxfilesystemaddhandler} to initialize
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a handler, for example:
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\begin{verbatim}
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#include <wx/fs_mem.h>
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...
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bool MyApp::OnInit()
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{
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wxFileSystem::AddHandler(new wxMemoryFSHandler);
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...
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}
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\end{verbatim}
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