elinks/doc/events.txt

				Events

This file lists the events currently in use, when they are called, what they
do and what arguments they expect.

Events are a mechanism for communication between ELinks parts --- any ELinks
subsystem (module) can register an event, hook at an event or trigger an event.
Events are designed to allow transition to a completely message-passing model
internally, with modules talking to each other through the events.

Events are currently used primarily as a generic way to trigger event handlers
in various scripting backends.

Therefore, so far this reference sheet is useful mainly to scripting backends
developers and also scripting power users - it looks at the C side but usually
you get most (if not all) of it passed to the hook functions in your scripts.



Below is a template showing how to read the event information

Name:		<event name>
Managed By:	<what part of the code registers and unregister the event>
Triggered When:

 <short description of when the event is triggered>

Arguments:

 <the order and type of the arguments>

Description:

 <description of the arguments, what the event does etc.>

Please keep in alphabetical order!



The list of events itself:

-------------------------------------------------------------------------------
Name:		bookmark-delete
Managed By:	The bookmarks subsystem
Triggered When:

 A bookmark is being deleted.

Arguments:

 struct bookmark *bookmark

Description:

 Currently only used by the tab snapshotting code to avoid a dangling pointer
 should the deleted bookmark be the folder to which it made the last snapshot.

-------------------------------------------------------------------------------
Name:		bookmark-move
Managed By:	The bookmarks subsystem
Triggered When:

 A bookmark is being moved.

Arguments:

 struct bookmark *bookmark
 struct bookmark *destination

Description:

 The bookmark is moved immediately after the destination bookmark.

 This is currently only used by the tab snapshotting code, which assumes
 that when a user moves a bookmark, the user does not want the snapshotting
 code to delete it when it makes the next snapshot.

-------------------------------------------------------------------------------
Name:		bookmark-update
Managed By:	The bookmarks subsystem
Triggered When:

 The user finishes editing a bookmark.

Arguments:

 struct bookmark *bookmark
 unsigned char *new_title
 unsigned char *new_url

Description:

 This is triggered before the new title and URL are assigned to the bookmark.
 Therefore, handlers can get the old title and URL from the bookmark structure
 and the new title and URL from the event arguments.

 This is currently only used by the tab snapshotting code, which assumes
 that when a user edits a bookmark, the user does not want the snapshotting
 code to delete it when it makes the next snapshot.

-------------------------------------------------------------------------------
Name:		dialog-lua-console
Managed By:	The Lua scripting subsystem/backend
Triggered When:

 The user hits a key associated with 'lua-console' action.

Arguments:

 struct session *ses

Description:

 Open Lua console dialog.

-------------------------------------------------------------------------------
Name:		follow-url
Managed By:	The scripting subsystem/backends
Triggered When:

 The user decides to load some document by following a link, entering a URL
 in the goto URL dialog, loading frames from a frameset (?) etc.

Arguments:

 unsigned char **url, struct session *ses

Description:

 If another URL than @url should be followed it is passed by setting @url.
 If @url is changed the event propagation should be ended.
 Valid values for @url includes:
 - unchanged, if the original URL should be followed;
 - a new, dynamically allocated URL to be followed instead; or
 - NULL or an empty, dynamically allocated string if no URL should be followed.

-------------------------------------------------------------------------------
Name:		free-history
Managed By:	The scripting subsystem/backends
Triggered When:

 ELinks exits

Arguments:

 None

Description:

 Allow a subsystem to free its history lists.

-------------------------------------------------------------------------------
Name:		get-proxy
Managed By:	The scripting subsystem/backends
Triggered When:

 Determining what proxy, if any, should be used to load a requested URL.

Arguments:

 unsigned char **new_proxy_url, unsigned char *url

Description:

 Possible values for @new_proxy_url includes:
 - a dynamically allocated string with the format proxy:port;
 - an empty string (dynamically allocated!) to use no proxy; or
 - NULL to use the default proxies.

-------------------------------------------------------------------------------
Name:		goto-url
Managed By:	The scripting subsystem/backends
Triggered When:

 The user enters something into the goto URL dialog.

Arguments:

 unsigned char **url, struct session *ses

Description:

 If a URL other than @url should be followed, the old one should be freed
 and the new one should be assigned to @url. @url must not be assigned
 NULL and must remain freeable.
 Valid values for @url are:
 - unchanged, if the original URL should be followed;
 - a new, dynamically allocated URL to be followed instead; or
 - NULL or an empty, dynamically allocated string if no URL should be followed.

 @ses is usually used for deciding based on the current URI or for reporting
 potential errors during the hook processing through the UI. With @ses being
 NULL the hook handler should assume no current URI and no suitable UI set up
 (i.e., starting up yet or -dump).

-------------------------------------------------------------------------------
Name:		periodic-saving
Managed By:	No maintainer but used by lowlevel/timer.*
Triggered When:

 The interval timer configured through option goes off.

Arguments:

 none

Description:

 Makes it possible to periodically save files in ~/.elinks to disk.

-------------------------------------------------------------------------------
Name:		pre-format-html
Managed By:	The scripting subsystem/backends
Triggered When:

 A HTML document has been loaded - before the document rendering begins.

Arguments:

 struct session *ses
 struct cache_entry *cached

Description:

 Makes it possible to fix up bad HTML code, remove tags etc. The parameter
 cached is guaranteed to have a single fragment. The HTML source is changed
 by replacing this fragment:

	add_fragment(cached, 0, new_string, new_len);
	normalize_cache_entry(cached, new_len);

 The caller must ensure that there is a reference to cached, so that
 calling garbage_collection() from the event handler cannot free it.

-------------------------------------------------------------------------------
Name:		quit
Managed By:	The scripting subsystem/backends
Triggered When:

 ELinks quits

Arguments:

 None

Description:

 Allows a subsystem to do whatever clean-up is required when ELinks quits.

-------------------------------------------------------------------------------