glib.Timeout.Timeout Class Reference

List of all members.

Detailed Description

Description The main event loop manages all the available sources of events for GLib and GTK+ applications.

These events can come from any number of different types of sources such as file descriptors (plain files, pipes or sockets) and timeouts. New types of event sources can also be added using g_source_attach(). To allow multiple independent sets of sources to be handled in different threads, each source is associated with a GMainContext. A GMainContext can only be running in a single thread, but sources can be added to it and removed from it from other threads. Each event source is assigned a priority. The default priority, G_PRIORITY_DEFAULT, is 0. Values less than 0 denote higher priorities. Values greater than 0 denote lower priorities. Events from high priority sources are always processed before events from lower priority sources. Idle functions can also be added, and assigned a priority. These will be run whenever no events with a higher priority are ready to be processed. The GMainLoop data type represents a main event loop. A GMainLoop is created with g_main_loop_new(). After adding the initial event sources, g_main_loop_run() is called. This continuously checks for new events from each of the event sources and dispatches them. Finally, the processing of an event from one of the sources leads to a call to g_main_loop_quit() to exit the main loop, and g_main_loop_run() returns. It is possible to create new instances of GMainLoop recursively. This is often used in GTK+ applications when showing modal dialog boxes. Note that event sources are associated with a particular GMainContext, and will be checked and dispatched for all main loops associated with that GMainContext. GTK+ contains wrappers of some of these functions, e.g. gtk_main(), gtk_main_quit() and gtk_events_pending(). Creating new sources types One of the unusual features of the GTK+ main loop functionality is that new types of event source can be created and used in addition to the builtin type of event source. A new event source type is used for handling GDK events. A new source type is created by deriving from the GSource structure. The derived type of source is represented by a structure that has the GSource structure as a first element, and other elements specific to the new source type. To create an instance of the new source type, call g_source_new() passing in the size of the derived structure and a table of functions. These GSourceFuncs determine the behavior of the new source types. New source types basically interact with with the main context in two ways. Their prepare function in GSourceFuncs can set a timeout to determine the maximum amount of time that the main loop will sleep before checking the source again. In addition, or as well, the source can add file descriptors to the set that the main context checks using g_source_add_poll().


Customizing the main loop iteration Single iterations of a GMainContext can be run with g_main_context_iteration(). In some cases, more detailed control of exactly how the details of the main loop work is desired, for instance, when integrating the GMainLoop with an external main loop. In such cases, you can call the component functions of g_main_context_iteration() directly. These functions are g_main_context_prepare(), g_main_context_query(), g_main_context_check() and g_main_context_dispatch(). The operation of these functions can best be seen in terms of a state diagram, as shown in Figure1, States of a Main Context. Figure1.States of a Main Context


Static Public Member Functions

static Source sourceNew (uint interval)
 Creates a new timeout source.
static Source sourceNewSeconds (uint interval)
 Creates a new timeout source.
static uint add (uint interval, GSourceFunc funct, void *data)
 Sets a function to be called at regular intervals, with the default priority, G_PRIORITY_DEFAULT.
static uint addFull (int priority, uint interval, GSourceFunc funct, void *data, GDestroyNotify notify)
 Sets a function to be called at regular intervals, with the given priority.
static uint addSeconds (uint interval, GSourceFunc funct, void *data)
 Sets a function to be called at regular intervals, with the default priority, G_PRIORITY_DEFAULT.


Member Function Documentation

static uint glib.Timeout.Timeout.add ( uint  interval,
GSourceFunc  funct,
void *  data 
) [static]

Sets a function to be called at regular intervals, with the default priority, G_PRIORITY_DEFAULT.

The function is called repeatedly until it returns FALSE, at which point the timeout is automatically destroyed and the function will not be called again. The first call to the function will be at the end of the first interval. Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval (it does not try to 'catch up' time lost in delays). If you want to have a timer in the "seconds" range and do not care about the exact time of the first call of the timer, use the g_timeout_add_seconds() function; this function allows for more optimizations and more efficient system power usage. interval: the time between calls to the function, in milliseconds (1/1000ths of a second) function: function to call data: data to pass to function Returns: the ID (greater than 0) of the event source.

static uint glib.Timeout.Timeout.addFull ( int  priority,
uint  interval,
GSourceFunc  funct,
void *  data,
GDestroyNotify  notify 
) [static]

Sets a function to be called at regular intervals, with the given priority.

The function is called repeatedly until it returns FALSE, at which point the timeout is automatically destroyed and the function will not be called again. The notify function is called when the timeout is destroyed. The first call to the function will be at the end of the first interval. Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval (it does not try to 'catch up' time lost in delays). priority: the priority of the idle source. Typically this will be in the range between G_PRIORITY_DEFAULT_IDLE and G_PRIORITY_HIGH_IDLE. interval: the time between calls to the function, in milliseconds (1/1000ths of a second) function: function to call data: data to pass to function notify: function to call when the idle is removed, or NULL Returns: the ID (greater than 0) of the event source.

static uint glib.Timeout.Timeout.addSeconds ( uint  interval,
GSourceFunc  funct,
void *  data 
) [static]

Sets a function to be called at regular intervals, with the default priority, G_PRIORITY_DEFAULT.

The function is called repeatedly until it returns FALSE, at which point the timeout is automatically destroyed and the function will not be called again. Unlike g_timeout_add(), this function operates at whole second granularity. The initial starting point of the timer is determined by the implementation and the implementation is expected to group multiple timers together so that they fire all at the same time. To allow this grouping, the interval to the first timer is rounded and can deviate up to one second from the specified interval. Subsequent timer iterations will generally run at the specified interval. Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval If you want timing more precise than whole seconds, use g_timeout_add() instead. The grouping of timers to fire at the same time results in a more power and CPU efficient behavior so if your timer is in multiples of seconds and you don't require the first timer exactly 1 second from now, the use of g_timeout_add_second() is prefered over g_timeout_add(). interval: the time between calls to the function, in seconds function: function to call data: data to pass to function Returns: the ID (greater than 0) of the event source. Since 2.14

static Source glib.Timeout.Timeout.sourceNew ( uint  interval  )  [static]

Creates a new timeout source.

The source will not initially be associated with any GMainContext and must be added to one with g_source_attach() before it will be executed. interval: the timeout interval in milliseconds. Returns: the newly-created timeout source

static Source glib.Timeout.Timeout.sourceNewSeconds ( uint  interval  )  [static]

Creates a new timeout source.

The source will not initially be associated with any GMainContext and must be added to one with g_source_attach() before it will be executed. The scheduling granularity/accuracy of this timeout source will be in seconds. interval: the timeout interval in seconds Returns: the newly-created timeout source Since 2.14


SourceForge.net Logo DSource.org Logo digitalmars.com Logo