docs/latex/wx/timer.tex

   1 \section{\class{wxTimer}}\label{wxtimer}
   2
   3 The wxTimer class allows you to execute code at specified intervals. Its
   4 precision is platform-dependent, but in general will not be better than 1ms nor
   5 worse than 1s.
   6
   7 There are three different ways to use this class:
   8
   9 \begin{enumerate}
  10 \item You may derive a new class from wxTimer and override the
  11 \helpref{Notify}{wxtimernotify} member to perform the required action.
  12 \item Or you may redirect the notifications to any
  13 \helpref{wxEvtHandler}{wxevthandler} derived object by using the non-default
  14 constructor or \helpref{SetOwner}{wxtimersetowner}. Then use the {\tt EVT\_TIMER}
  15 macro to connect it to the event handler which will receive
  16 \helpref{wxTimerEvent}{wxtimerevent} notifications.
  17 \item Or you may use a derived class and the {\tt EVT\_TIMER}
  18 macro to connect it to an event handler defined in the derived class.
  19 If the default constructor is used, the timer object will be its
  20 own owner object, since it is derived from wxEvtHandler.
  21 \end{enumerate}
  22
  23 In any case, you must start the timer with \helpref{Start}{wxtimerstart}
  24 after constructing it before it actually starts sending notifications. It can
  25 be stopped later with \helpref{Stop}{wxtimerstop}.
  26
  27 {\bf Note:} A timer can only be used from the main thread.
  28
  29 \wxheading{Derived from}
  30
  31 \helpref{wxEvtHandler}{wxevthandler}
  32 \helpref{wxObject}{wxobject}
  33
  34 \wxheading{Include files}
  35
  36 <wx/timer.h>
  37
  38 \wxheading{See also}
  39
  40 \helpref{::wxStartTimer}{wxstarttimer}, \helpref{::wxGetElapsedTime}{wxgetelapsedtime}, \helpref{wxStopWatch}{wxstopwatch}
  41
  42 \latexignore{\rtfignore{\wxheading{Members}}}
  43
  44 \membersection{wxTimer::wxTimer}\label{wxtimerwxtimer}
  45
  46 \func{}{wxTimer}{\void}
  47
  48 Default constructor. If you use it to construct the object and don't call
  49 \helpref{SetOwner}{wxtimersetowner} later, you must override
  50 \helpref{Notify}{wxtimernotify} method to process the notifications.
  51
  52 \func{}{wxTimer}{\param{wxEvtHandler *}{owner}, \param{int }{id = -1}}
  53
  54 Creates a timer and associates it with {\it owner}. Please see
  55 \helpref{SetOwner}{wxtimersetowner} for the description of parameters.
  56
  57 \membersection{wxTimer::\destruct{wxTimer}}\label{wxtimerdtor}
  58
  59 \func{}{\destruct{wxTimer}}{\void}
  60
  61 Destructor. Stops the timer if it is running.
  62
  63 \membersection{wxTimer::GetInterval}\label{wxtimergetinterval}
  64
  65 \constfunc{int}{GetInterval}{\void}
  66
  67 Returns the current interval for the timer (in milliseconds).
  68
  69 \membersection{wxTimer::IsOneShot}\label{wxtimerisoneshot}
  70
  71 \constfunc{bool}{IsOneShot}{\void}
  72
  73 Returns {\tt true} if the timer is one shot, i.e.\ if it will stop after firing the
  74 first notification automatically.
  75
  76 \membersection{wxTimer::IsRunning}\label{wxtimerisrunning}
  77
  78 \constfunc{bool}{IsRunning}{\void}
  79
  80 Returns {\tt true} if the timer is running, {\tt false} if it is stopped.
  81
  82 \membersection{wxTimer::Notify}\label{wxtimernotify}
  83
  84 \func{void}{Notify}{\void}
  85
  86 This member should be overridden by the user if the default constructor was
  87 used and \helpref{SetOwner}{wxtimersetowner} wasn't called.
  88
  89 Perform whatever action which is to be taken periodically here.
  90
  91 \membersection{wxTimer::SetOwner}\label{wxtimersetowner}
  92
  93 \func{void}{SetOwner}{\param{wxEvtHandler *}{owner}, \param{int }{id = -1}}
  94
  95 Associates the timer with the given {\it owner}\/ object. When the timer is
  96 running, the owner will receive \helpref{timer events}{wxtimerevent} with
  97 id equal to {\it id}\/ specified here.
  98
  99 \membersection{wxTimer::Start}\label{wxtimerstart}
 100
 101 \func{bool}{Start}{\param{int }{milliseconds = -1}, \param{bool }{oneShot = {\tt false}}}
 102
 103 (Re)starts the timer. If {\it milliseconds}\/ parameter is -1 (value by default),
 104 the previous value is used. Returns {\tt false} if the timer could not be started,
 105 {\tt true} otherwise (in MS Windows timers are a limited resource).
 106
 107 If {\it oneShot}\/ is {\tt false} (the default), the \helpref{Notify}{wxtimernotify}
 108 function will be called repeatedly until the timer is stopped. If {\tt true},
 109 it will be called only once and the timer will stop automatically. To make your
 110 code more readable you may also use the following symbolic constants:
 111
 112 \twocolwidtha{5cm}
 113 \begin{twocollist}\itemsep=0pt
 114 \twocolitem{wxTIMER\_CONTINUOUS}{Start a normal, continuously running, timer}
 115 \twocolitem{wxTIMER\_ONE\_SHOT}{Start a one shot timer}
 116 \end{twocollist}
 117
 118 If the timer was already running, it will be stopped by this method before
 119 restarting it.
 120
 121 \membersection{wxTimer::Stop}\label{wxtimerstop}
 122
 123 \func{void}{Stop}{\void}
 124
 125 Stops the timer.
 126
 127 \section{\class{wxTimerEvent}}\label{wxtimerevent}
 128
 129 wxTimerEvent object is passed to the event handler of timer events.
 130
 131 For example:
 132
 133 \begin{verbatim}
 134 class MyFrame : public wxFrame
 135 {
 136 public:
 137     ...
 138     void OnTimer(wxTimerEvent& event);
 139
 140 private:
 141     wxTimer m_timer;
 142 };
 143
 144 BEGIN_EVENT_TABLE(MyFrame, wxFrame)
 145     EVT_TIMER(TIMER_ID, MyFrame::OnTimer)
 146 END_EVENT_TABLE()
 147
 148 MyFrame::MyFrame()
 149        : m_timer(this, TIMER_ID)
 150 {
 151     m_timer.Start(1000);    // 1 second interval
 152 }
 153
 154 void MyFrame::OnTimer(wxTimerEvent& event)
 155 {
 156     // do whatever you want to do every second here
 157 }
 158
 159 \end{verbatim}
 160
 161 \wxheading{Derived from}
 162
 163 \helpref{wxEvent}{wxevent}
 164
 165 \wxheading{Include files}
 166
 167 <wx/timer.h>
 168
 169 \wxheading{See also}
 170
 171 \helpref{wxTimer}{wxtimer}
 172
 173 \latexignore{\rtfignore{\wxheading{Members}}}
 174
 175 \membersection{wxTimerEvent::GetInterval}\label{wxtimereventgetinterval}
 176
 177 \constfunc{int}{GetInterval}{\void}
 178
 179 Returns the interval of the timer which generated this event.
 180