gnome-triggers

Description

The triggers API provides a way for applications to tell GNOME about interesting events that then cause something to happen (for example, playing a sound). An event can either be a function that is called, a sound that is played or an external command that is run.

Each trigger can optionally have a level associated with it and a section. The section is a list of strings that help to classify the event, which imposes a hierarchy on the trigger system. For example, messages about the hard drive partition /dev/hda1 may come under the section ("system", "device", "disk", "/dev/hda1"). This means that an application could trigger all events for the ("system", "device") sections and include those events, or be more specific and just trigger those for ("system", "device", "disk", "/dev/hda1").

At the present time, triggers are not widely used in GNOME, being mostly used to play sound events in response to certain actions.

Details

enum GnomeTriggerType

typedef enum {
	GTRIG_NONE,
	GTRIG_FUNCTION,
	GTRIG_COMMAND,
	GTRIG_MEDIAPLAY
} GnomeTriggerType;

These are the different types of triggers that can be activated by an application.

`GTRIG_NONE`	A null trigger type. Should never be used.
`GTRIG_FUNCTION`	The trigger causes a function to be executed.
`GTRIG_COMMAND`	The trigger causes a command to be executed (using execv()).
`GTRIG_MEDIAPLAY`	The trigger causes a sound to be played.

GnomeTriggerActionFunction ()

void        (*GnomeTriggerActionFunction)   (char *msg,
                                             char *level,
                                             char *supinfo[]);

The signature of a function that can used as a target for GTRIG_FUNCTION types of GnomeTrigger instances.

`msg` :	The human-readable message that was passed to gnome_triggers_do(). May be `NULL`.
`level` :	The severity level of the event. May be `NULL`.
`supinfo` :	The section in which the event belongs. This is a `NULL` terminated array.

struct GnomeTrigger

struct GnomeTrigger {
	GnomeTriggerType type;
	union {
		/*
		 * These will be passed the same info as
		 * gnome_triggers_do was given.
		 */
		GnomeTriggerActionFunction function;
		gchar *command;
		struct {
			gchar *file;
			int cache_id;
		} media;
	} u;
        gchar *level;
};

This structure stores the information about an action that is triggered for a particular event. A filled in instance of this structure is passed to gnome_triggers_add_trigger() and gnome_triggers_vadd_trigger().

gnome_triggers_add_trigger ()

void        gnome_triggers_add_trigger      (GnomeTrigger *nt,
                                             ...);

Adds a new GnomeTrigger instance to the event hierarchy.

`nt` :	Information on the new trigger to be added.
`...` :	The section to add the trigger under.

gnome_triggers_vadd_trigger ()

void        gnome_triggers_vadd_trigger     (GnomeTrigger *nt,
                                             char *supinfo[]);

This does the same as gnome_triggers_add_trigger(), except the section is stored in the NULL terminated array supinfo instead of as a variable length argument list.

`nt` :	Information on the new trigger to be added.
`supinfo` :	The section to add the trigger under.

gnome_triggers_do ()

void        gnome_triggers_do               (const char *msg,
                                             const char *level,
                                             ...);

Notifies GNOME about an event happening, so that any appropriate handlers can be run.

`msg` :	The human-readable message describing the event (can be `NULL`).
`level` :	The level of severity of the event, or `NULL`.
`...` :	The classification of the event.

gnome_triggers_vdo ()

void        gnome_triggers_vdo              (const char *msg,
                                             const char *level,
                                             const char *supinfo[]);

Notifies GNOME about an event happening, so that any appropriate handlers can be run. This does the same as gnome_trigger_do() except that it takes a NULL terminated array instead of a varargs list.

`msg` :	The human-readable message describing the event (can be `NULL`).
`level` :	The level of severity of the event, or `NULL`.
`supinfo` :	The classification of the event (`NULL` terminated array).