wxWidgets/interface/timer.h

/////////////////////////////////////////////////////////////////////////////
// Name:        timer.h
// Purpose:     documentation for wxTimer class
// Author:      wxWidgets team
// RCS-ID:      $Id$
// Licence:     wxWindows license
/////////////////////////////////////////////////////////////////////////////

/**
    @class wxTimer
    @wxheader{timer.h}
    
    The wxTimer class allows you to execute code at specified intervals. Its
    precision is platform-dependent, but in general will not be better than 1ms nor
    worse than 1s.
    
    There are three different ways to use this class:
    
     You may derive a new class from wxTimer and override the 
    wxTimer::Notify member to perform the required action.
     Or you may redirect the notifications to any 
    wxEvtHandler derived object by using the non-default
    constructor or wxTimer::SetOwner. Then use the @c EVT_TIMER 
    macro to connect it to the event handler which will receive 
    wxTimerEvent notifications.
     Or you may use a derived class and the @c EVT_TIMER 
    macro to connect it to an event handler defined in the derived class.
    If the default constructor is used, the timer object will be its
    own owner object, since it is derived from wxEvtHandler.
    
    In any case, you must start the timer with wxTimer::Start 
    after constructing it before it actually starts sending notifications. It can
    be stopped later with wxTimer::Stop.
    
    @b Note: A timer can only be used from the main thread.
    
    @library{wxbase}
    @category{misc}
    
    @seealso
    wxStopWatch
*/
class wxTimer : public wxEvtHandler
{
public:
    //@{
    /**
        Creates a timer and associates it with @e owner. Please see 
        SetOwner() for the description of parameters.
    */
    wxTimer();
        wxTimer(wxEvtHandler * owner, int id = -1);
    //@}

    /**
        Destructor. Stops the timer if it is running.
    */
    ~wxTimer();

    /**
        Returns the ID of the events generated by this timer.
    */
    int GetId();

    /**
        Returns the current interval for the timer (in milliseconds).
    */
    int GetInterval();

    /**
        Returns the current @e owner of the timer.
        If non-@NULL this is the event handler which will receive the 
        @ref overview_wxtimerevent "timer events" when the timer is running.
    */
    wxEvtHandler GetOwner();

    /**
        Returns @true if the timer is one shot, i.e. if it will stop after firing the
        first notification automatically.
    */
    bool IsOneShot();

    /**
        Returns @true if the timer is running, @false if it is stopped.
    */
    bool IsRunning();

    /**
        This member should be overridden by the user if the default constructor was
        used and SetOwner() wasn't called.
        
        Perform whatever action which is to be taken periodically here.
    */
    void Notify();

    /**
        Associates the timer with the given @e owner object. When the timer is
        running, the owner will receive @ref overview_wxtimerevent "timer events" with
        id equal to @e id specified here.
    */
    void SetOwner(wxEvtHandler * owner, int id = -1);

    /**
        (Re)starts the timer. If @e milliseconds parameter is -1 (value by default),
        the previous value is used. Returns @false if the timer could not be started,
        @true otherwise (in MS Windows timers are a limited resource).
        
        If @e oneShot is @false (the default), the Notify() 
        function will be called repeatedly until the timer is stopped. If @true,
        it will be called only once and the timer will stop automatically. To make your
        code more readable you may also use the following symbolic constants:
        
        
        wxTIMER_CONTINUOUS
        
        
        Start a normal, continuously running, timer
        
        wxTIMER_ONE_SHOT
        
        
        Start a one shot timer
        
        If the timer was already running, it will be stopped by this method before
        restarting it.
    */
    bool Start(int milliseconds = -1, bool oneShot = @false);

    /**
        Stops the timer.
    */
    void Stop();
};


/**
    @class wxTimerEvent
    @wxheader{timer.h}
    
    wxTimerEvent object is passed to the event handler of timer events.
    
    For example:
    
    @code
    class MyFrame : public wxFrame
    {
    public:
        ...
        void OnTimer(wxTimerEvent& event);
    
    private:
        wxTimer m_timer;
    };
    
    BEGIN_EVENT_TABLE(MyFrame, wxFrame)
        EVT_TIMER(TIMER_ID, MyFrame::OnTimer)
    END_EVENT_TABLE()
    
    MyFrame::MyFrame()
           : m_timer(this, TIMER_ID)
    {
        m_timer.Start(1000);    // 1 second interval
    }
    
    void MyFrame::OnTimer(wxTimerEvent& event)
    {
        // do whatever you want to do every second here
    }
    @endcode
    
    @library{wxbase}
    @category{events}
    
    @seealso
    wxTimer
*/
class wxTimerEvent : public wxEvent
{
public:
    /**
        Returns the interval of the timer which generated this event.
    */
    int GetInterval();

    /**
        Returns the timer object which generated this event.
    */
    wxTimer GetTimer();
};