The wxHTML library uses a 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.
Classes
Three classes are used in order to provide virtual file systems mechanism:
Locations
Locations (aka filenames aka addresses) are constructed from four parts:
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 ZIP archive that is located on some FTP server:
ftp:ftp.archives.org/pub/cpp_doc.zip#zip:reference/fopen.htm#syntax
In fact, you have to use 'left location' even when accessing local ZIPs:
file:archives/cpp_doc.zip#zip:reference/fopen.htm#syntax
In this example, the protocol is "zip", the left location is "reference/fopen.htm", the anchor is "syntax" and the right location is "file:archives/cpp_doc.zip".
There are two protocols used in this example: "zip" and "file". You can construct even more complicated addresses like this one:
http://www.archives.org/myarchive.zip#zip:local/docs/cpp/stdio.zip#zip:index.htm
In this example you access zip virtual file system stdio.zip stored in another zip (myarchive.zip) which can be found at WWW.
File Systems Included in wxHTML
The following virtual file system handlers are part of wxWindows so far:
wxInternetFSHandler | A handler for accessing documents via HTTP or FTP protocols. Include file is <wx/fs_inet.h>. |
wxZipFSHandler | A handler for ZIP archives. Include file is <wx/fs_zip.h>. URL is in form "archive.zip#zip:filename". |
wxMemoryFSHandler | This handler allows you to access data stored in memory (such as bitmaps) as if they were regular files. See wxMemoryFSHandler documentation for details. Include file is <wx/fs_mem.h>. UURL is prefixed with memory:, e.g. "memory:myfile.htm" |
In addition, wxFileSystem itself can access local files.
Initializing file system handlers
Use wxFileSystem::AddHandler to initialize a handler, for example:
#include <wx/fs_mem.h> ... bool MyApp::OnInit() { wxFileSystem::AddHandler(new wxMemoryFSHandler); ... }