NAME
SoSensorManager -
The SoSensorManager class handles the sensor queues.
There are two major sensor types in Coin, ’delay’ sensors and ’timer’
sensors:
SYNOPSIS
#include <Inventor/sensors/SoSensorManager.h>
Public Member Functions
SoSensorManager (void)
~SoSensorManager ()
void insertDelaySensor (SoDelayQueueSensor *s)
void insertTimerSensor (SoTimerQueueSensor *s)
void removeDelaySensor (SoDelayQueueSensor *s)
void removeTimerSensor (SoTimerQueueSensor *s)
void setChangedCallback (void(*sensorQueueChangedCB)(void *), void
*data)
void rescheduleTimer (SoTimerSensor *s)
void removeRescheduledTimer (SoTimerQueueSensor *s)
void processDelayQueue (SbBool isidle)
void processImmediateQueue (void)
void processTimerQueue (void)
SbBool isDelaySensorPending (void)
SbBool isTimerSensorPending (SbTime &tm)
void setDelaySensorTimeout (const SbTime &t)
const SbTime & getDelaySensorTimeout (void)
int doSelect (int nfds, void *readfds, void *writefds, void *exceptfds,
struct timeval *userTimeOut)
Detailed Description
The SoSensorManager class handles the sensor queues.
There are two major sensor types in Coin, ’delay’ sensors and ’timer’
sensors:
· Delay sensors trigger when the application is otherwise idle. In
addition, to avoid starvation in applications that are continually
busy, the delay-sensor queue also has a timeout which, when reached,
will empty the queue anyhow.
· Timer sensors are set up to trigger at specific, absolute times.
Each of these two types has its own queue, which is handled by the
SoSensorManager. The queues are kept in sorted order by
SoSensorManager, either according to trigger-time (for timer sensors)
or by priority (for delay sensors).
The SoSensorManager provides methods for managing these queues, by
insertion and removal of sensors, and processing (emptying) of the
queues.
The sensor mechanism is crucial in Coin for a number of important
features, most notably automatic scheduling redrawal upon changes, and
for making it possible to set up animations in the scenegraph which
does not need any additional book-keeping from the application code.
SoSensorManager should usually be considered as an internal class in
the Coin API. It is only interesting for application programmers when
implementing new windowsystem-specific libraries (like Kongsberg Oil &
Gas Technologies SoQt, SoXt, SoGtk, SoWin or Sc21) or wrappers. Then
one has to set up code to empty the queues at the correct intervals.
For detailed information on how to do that, we would advise you to look
at the implementation of said mechanisms in the So*-libraries which SIM
provides.
Please note that before Coin 2.3.1, sensors with equal priority (or the
same trigger time for SoTimerQueue sensors) were processed LIFO. This
has now been changed to FIFO to be conformant to SGI Inventor.
See also:
SoSensor SoTimerQueueSensor SoDelayQueueSensor
SoTimerSensor SoAlarmSensor
SoIdleSensor SoDataSensor SoOneShotSensor
SoPathSensor SoFieldSensor SoNodeSensor
Constructor & Destructor Documentation
SoSensorManager::SoSensorManager (void) Constructor.
SoSensorManager::~SoSensorManager () Destructor.
Member Function Documentation
void SoSensorManager::insertDelaySensor (SoDelayQueueSensor * newentry) Add
a new entry to the queue of delay sensors.
See also:
removeFromQueue()
void SoSensorManager::insertTimerSensor (SoTimerQueueSensor * newentry) Add
a new entry to the timer queue of sensors. The queue will be sorted in
order of supposed trigger time.
See also:
removeFromQueue()
void SoSensorManager::removeDelaySensor (SoDelayQueueSensor * entry) Remove
an entry from the queue of prioritized sensors.
See also:
addToQueue()
void SoSensorManager::removeTimerSensor (SoTimerQueueSensor * entry) Remove
an entry from the queue of timer sensors.
void SoSensorManager::setChangedCallback (void(*)(void *) func, void *
data) For setting up a callback function to be invoked whenever any of
the sensor queues are changed.
This callback should typically be responsible for updating the client-
side mechanism which is used for processing the queues.
void SoSensorManager::rescheduleTimer (SoTimerSensor * s) This API member
is considered internal to the library, as it is not likely to be of
interest to the application programmer.
void SoSensorManager::removeRescheduledTimer (SoTimerQueueSensor * s) This
API member is considered internal to the library, as it is not likely
to be of interest to the application programmer.
void SoSensorManager::processDelayQueue (SbBool isidle) Trigger all delay
queue entries in priority order.
The isidle flag indicates whether or not the processing happens because
the application is idle or because the delay queue timeout was reached.
A delay queue sensor with priority > 0 can only be triggered once
during a call to this function. If a delay sensor is rescheduled during
processDelayQueue(), it is not processed until the next time this
function is called. This is done to avoid an infinite loop while
processing the sensors.
A delay queue sensor with priority 0 is called an immediate sensor.
See also:
SoDB::setDelaySensorTimeout()
SoSensorManager::processImmediateQueue()
void SoSensorManager::processImmediateQueue (void) Process all immediate
sensors (delay sensors with priority 0).
Be aware that you might risk an infinite loop using immediate sensors.
Unlike delay queue sensors, immediate sensors can be rescheduled and
triggered multiple times during immediate queue processing.
See also:
SoDelayQueueSensor::setPriority()
void SoSensorManager::processTimerQueue (void) Trigger all the timers which
has expired.
SbBool SoSensorManager::isDelaySensorPending (void) Returns TRUE if at
least one delay sensor or immediate sensor is present in the respective
queue, otherwise FALSE.
SbBool SoSensorManager::isTimerSensorPending (SbTime & tm) Returns TRUE if
at least one timer sensor is present in the queue, otherwise FALSE.
If sensors are pending, the time interval until the next one should be
triggered will be put in the tm variable.
void SoSensorManager::setDelaySensorTimeout (const SbTime & t) Delay
sensors are usually triggered only when the system is idle. But when
there are continuous updates to the scene graph, there’s a possibility
that the delay queue will starve and sensors are never triggered. To
make sure this won’t happen, this is a timeout value for the delay
queue. When this timeout has been reached, the sensors in the delay
queue gets processed before other sensors and events. This method will
let the user set this timeout value.
The default value is 1/12 of a second.
Specifying a zero time will disable the timeout, opening for potential
delay queue starvation.
See also:
getDelaySensorTimeout(), SoDelayQueueSensor
const SbTime & SoSensorManager::getDelaySensorTimeout (void) Returns the
timeout value for sensors in the delay queue.
See also:
setDelaySensorTimeout(), SoDelayQueueSensor
int SoSensorManager::doSelect (int nfds, void * readfds, void * writefds,
void * exceptfds, struct timeval * usertimeout) NOTE: THIS METHOD IS
OBSOLETED. DON’T USE IT.
This is a wrapper around the standard select(2) call, which will make
sure the sensor queues are updated while waiting for any action to
happen on the given file descriptors.
The void* arguments must be valid pointers to fd_set structures. We’ve
changed this from the original SGI Inventor API to avoid messing up the
header file with system-specific includes.
NOTE: THIS METHOD IS OBSOLETED. DON’T USE IT.
Author
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