VkPeriodic(3x)

NAME
     VkPeriodic - Support for performing actions at regular periodic intervals

INHERITS FROM
     VkCallbackObject

HEADER FILE
     #include <Vk/VkPeriodic.h>

PUBLIC PROTOCOL SUMMARY
   Constructor/Destructor
           VkPeriodic(int interval);
           virtual void ~VkPeriodic(void);


   Starting and Stopping
           void start(void);
           void stop(void);


PROTECTED PROTOCOL SUMMARY
   Updates
           virtual void tick(void);


   Protected Data Members
CLASS DESCRIPTION
          VkPeriodic provides a simple, convenient interface to the Xt timeout
          mechanism. For many applications, it is sufficient to call
          XtAppAddTimeOut() directly. However, VkPeriodic provides the ability
          to encapsulate a common use of XtAppAddTimeOut(), as a cyclic timer,
          in a C++ class.

          The VkPeriodic class can be used in one of two way. The first is to
          derive a new class from VkPeriodic that overrides the tick() virtual
          member function. The tick() member function is called for each cycle
          of the periodic timeout. This approach has the advantage that any
          data being used in connection with the timeout can be declared and
          maintained as data member(s) of the derived class.

          The VkPeriodic class also supports a ViewKit callback that allows
          other C++ classes to register member functions to be called with
          each periodic timeout. This approach is more convenient when a
          simple timer is needed to drive some other class.

          These two methods are not mutually-exclusive, and both approaches
          may be used together at once.

FUNCTION DESCRIPTIONS
   tick()
           virtual void tick(void);


          This function can be overridden by derived classes to allow them to
          be notified when each timeout occurs.

   VkPeriodic()
           VkPeriodic(int interval);


          The constructor initializes a VkPeriodic object, creating a timer to
          be called every interval milliseconds. The interval is approximate
          because it relies on the underlying Xt mechanism, which is based on
          select(). If an application does not return to the Xt event loop
          regularly, the timeout will not occur.

   ~VkPeriodic()
           virtual void ~VkPeriodic(void);


          Clean up all memory allocated by a VkPeriodic object. Any pending
          timer is removed.

   start()
           void start(void);


          Start the timer. This function must be called to start the periodic
          timeouts.

   stop()
           void stop(void);


          Stop the timer.

   static const char *const timerCallback;
           static const char *const timerCallback;


          This callback list allows other C++ classes derived from
          VkCallbackObject to register member functions to be called at
          periodic intervals.

INHERITED MEMBER FUNCTIONS
   Inherited from VkCallbackObject
          callCallbacks(), addCallback(), removeCallback(),
          removeAllCallbacks()

     ViewKit Programmer's Guide
     The X Window System, DEC Press, Bob Sheifler and Jim Gettys
     The X Window System Toolkit, DEC Press, Paul Asente and Ralph Swick
     The OSF/Motif Programmers Reference, Prentice Hall, OSF