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Compress events as part of the frame cycle

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Instead of trying to guess about which motion events are
extraneous, queue up all events until we process a frame.
This allows us to look ahead and reliably compress consecutive
sequence of motion events.

clutter-main.c: Feed received events to the stage for queueing.
  Remove old compression code. Remove clutter_get_motion_events_frequency()
  clutter_set_motion_events_frequency()
clutter-stage.c: Keep a queue of pending events.
clutter-master-clock.c: Add processng of queued events to the
  clock source dispatch function.

http://bugzilla.openedhand.com/show_bug.cgi?id=1637

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
This commit is contained in:
Owen W. Taylor
2009-06-06 19:10:41 -04:00
committed by Emmanuele Bassi
parent 89a8fd7755
commit 6e69692e22
5 changed files with 136 additions and 114 deletions
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129
clutter/clutter-main.c
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@ -2004,6 +2004,29 @@ generate_enter_leave_events (ClutterEvent *event)
*/
void
clutter_do_event (ClutterEvent *event)
{
if (!event->any.stage)
return;
/* Instead of processing events when received, we queue them up to
* handle per-frame before animations, layout, and drawing.
*
* This gives us the chance to reliably compress motion events
* because we've "looked ahead" and know all motion events that
* will occur before drawing the frame.
*/
_clutter_stage_queue_event (event->any.stage, event);
}
/**
* _clutter_process_event
* @event: a #ClutterEvent.
*
* Does the actual work of processing an event that was queued earlier
* out of clutter_do_event().
*/
void
_clutter_process_event (ClutterEvent *event)
{
/* FIXME: This should probably be clutter_cook_event() - it would
* take a raw event from the backend and 'cook' it so its more tasty.
@ -2013,8 +2036,6 @@ clutter_do_event (ClutterEvent *event)
ClutterBackend *backend;
ClutterActor *stage;
ClutterInputDevice *device = NULL;
static gint32 motion_last_time = 0L;
gint32 local_motion_time;
context = clutter_context_get_default ();
backend = context->backend;
@ -2091,52 +2112,6 @@ clutter_do_event (ClutterEvent *event)
case CLUTTER_MOTION:
device = event->motion.device;
if (device)
local_motion_time = device->motion_last_time;
else
local_motion_time = motion_last_time;
/* avoid rate throttling for synthetic motion events or if
* the per-actor events are disabled
*/
if (!(event->any.flags & CLUTTER_EVENT_FLAG_SYNTHETIC) ||
!context->motion_events_per_actor)
{
gint32 frame_rate, delta;
/* avoid issuing too many motion events, which leads to many
* redraws in pick mode (performance penalty)
*/
frame_rate = clutter_get_motion_events_frequency ();
delta = 1000 / frame_rate;
CLUTTER_NOTE (EVENT,
"skip motion event: %s (last:%d, delta:%d, time:%d)",
(event->any.time < (local_motion_time + delta) ? "yes" : "no"),
local_motion_time,
delta,
event->any.time);
/* we need to guard against roll-overs and the
* case where the time is rolled backwards and
* the backend is not ensuring a monotonic clock
* for the events.
*
* see:
* http://bugzilla.openedhand.com/show_bug.cgi?id=1130
*/
if (event->any.time >= local_motion_time &&
event->any.time < (local_motion_time + delta))
break;
else
local_motion_time = event->any.time;
}
if (device)
device->motion_last_time = local_motion_time;
else
motion_last_time = local_motion_time;
/* Only stage gets motion events if clutter_set_motion_events is TRUE,
* and the event is not a synthetic event with source set.
*/
@ -2321,9 +2296,6 @@ clutter_base_init (void)
* Retrieves the default frame rate used when creating #ClutterTimeline<!--
* -->s.
*
* This value is also used to compute the default frequency of motion
* events.
*
* Return value: the default frame rate
*
* Since: 0.6
@ -2621,61 +2593,6 @@ clutter_get_keyboard_grab (void)
return context->keyboard_grab_actor;
}
/**
* clutter_get_motion_events_frequency:
*
* Retrieves the number of motion events per second that are delivered
* to the stage.
*
* See clutter_set_motion_events_frequency().
*
* Return value: the number of motion events per second
*
* Since: 0.6
*/
guint
clutter_get_motion_events_frequency (void)
{
ClutterMainContext *context = clutter_context_get_default ();
if (G_LIKELY (context->motion_frequency == 0))
{
guint frequency;
frequency = clutter_default_fps / 4;
frequency = CLAMP (frequency, 20, 45);
return frequency;
}
else
return context->motion_frequency;
}
/**
* clutter_set_motion_events_frequency:
* @frequency: the number of motion events per second, or 0 for the
* default value
*
* Sets the motion events frequency. Setting this to a non-zero value
* will override the default setting, so it should be rarely used.
*
* Motion events are delivered from the default backend to the stage
* and are used to generate the enter/leave events pair. This might lead
* to a performance penalty due to the way the actors are identified.
* Using this function is possible to reduce the frequency of the motion
* events delivery to the stage.
*
* Since: 0.6
*/
void
clutter_set_motion_events_frequency (guint frequency)
{
ClutterMainContext *context = clutter_context_get_default ();
/* never allow the motion events to exceed the default frame rate */
context->motion_frequency = CLAMP (frequency, 1, clutter_default_fps);
}
/**
* clutter_clear_glyph_cache:
*