src/common/evtloopcmn.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/evtloopcmn.cpp
   3 // Purpose:     common wxEventLoop-related stuff
   4 // Author:      Vadim Zeitlin
   5 // Modified by:
   6 // Created:     2006-01-12
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) 2006 Vadim Zeitlin <vadim@wxwindows.org>
   9 // Licence:     wxWindows licence
  10 ///////////////////////////////////////////////////////////////////////////////
  11
  12 // for compilers that support precompilation, includes "wx.h".
  13 #include "wx/wxprec.h"
  14
  15 #ifdef __BORLANDC__
  16     #pragma hdrstop
  17 #endif
  18
  19 #include "wx/evtloop.h"
  20
  21 #ifndef WX_PRECOMP
  22     #include "wx/app.h"
  23 #endif //WX_PRECOMP
  24
  25 // ----------------------------------------------------------------------------
  26 // wxEventLoopBase
  27 // ----------------------------------------------------------------------------
  28
  29 wxEventLoopBase *wxEventLoopBase::ms_activeLoop = NULL;
  30
  31 wxEventLoopBase::wxEventLoopBase()
  32 {
  33     m_isInsideYield = false;
  34     m_eventsToProcessInsideYield = wxEVT_CATEGORY_ALL;
  35 }
  36
  37 bool wxEventLoopBase::IsMain() const
  38 {
  39     if (wxTheApp)
  40         return wxTheApp->GetMainLoop() == this;
  41     return false;
  42 }
  43
  44 /* static */
  45 void wxEventLoopBase::SetActive(wxEventLoopBase* loop)
  46 {
  47     ms_activeLoop = loop;
  48
  49     if (wxTheApp)
  50         wxTheApp->OnEventLoopEnter(loop);
  51 }
  52
  53 void wxEventLoopBase::OnExit()
  54 {
  55     if (wxTheApp)
  56         wxTheApp->OnEventLoopExit(this);
  57 }
  58
  59 void wxEventLoopBase::WakeUpIdle()
  60 {
  61     WakeUp();
  62 }
  63
  64 bool wxEventLoopBase::ProcessIdle()
  65 {
  66     return wxTheApp && wxTheApp->ProcessIdle();
  67 }
  68
  69 bool wxEventLoopBase::Yield(bool onlyIfNeeded)
  70 {
  71     if ( m_isInsideYield )
  72     {
  73         if ( !onlyIfNeeded )
  74         {
  75             wxFAIL_MSG( wxT("wxYield called recursively" ) );
  76         }
  77
  78         return false;
  79     }
  80
  81     return YieldFor(wxEVT_CATEGORY_ALL);
  82 }
  83
  84 // wxEventLoopManual is unused in the other ports
  85 #if defined(__WINDOWS__) || defined(__WXDFB__) || ( ( defined(__UNIX__) && !defined(__WXOSX__) ) && wxUSE_BASE)
  86
  87 // ============================================================================
  88 // wxEventLoopManual implementation
  89 // ============================================================================
  90
  91 wxEventLoopManual::wxEventLoopManual()
  92 {
  93     m_exitcode = 0;
  94     m_shouldExit = false;
  95 }
  96
  97 bool wxEventLoopManual::ProcessEvents()
  98 {
  99     // process pending wx events first as they correspond to low-level events
 100     // which happened before, i.e. typically pending events were queued by a
 101     // previous call to Dispatch() and if we didn't process them now the next
 102     // call to it might enqueue them again (as happens with e.g. socket events
 103     // which would be generated as long as there is input available on socket
 104     // and this input is only removed from it when pending event handlers are
 105     // executed)
 106     if ( wxTheApp )
 107     {
 108         const bool hadExitedBefore = m_shouldExit;
 109
 110         wxTheApp->ProcessPendingEvents();
 111
 112         // One of the pending event handlers could have decided to exit the
 113         // loop so check for the flag before trying to dispatch more events
 114         // (which could block indefinitely if no more are coming).
 115         if ( !hadExitedBefore && m_shouldExit )
 116         {
 117             // We still need to dispatch any remaining pending events, just as
 118             // we do in the event loop in Run() if the loop is exited from a
 119             // normal event handler.
 120             while ( wxTheApp->HasPendingEvents() )
 121                 wxTheApp->ProcessPendingEvents();
 122
 123             return false;
 124         }
 125     }
 126
 127     return Dispatch();
 128 }
 129
 130 int wxEventLoopManual::Run()
 131 {
 132     // event loops are not recursive, you need to create another loop!
 133     wxCHECK_MSG( !IsRunning(), -1, wxT("can't reenter a message loop") );
 134
 135     // ProcessIdle() and ProcessEvents() below may throw so the code here should
 136     // be exception-safe, hence we must use local objects for all actions we
 137     // should undo
 138     wxEventLoopActivator activate(this);
 139
 140     // we must ensure that OnExit() is called even if an exception is thrown
 141     // from inside ProcessEvents() but we must call it from Exit() in normal
 142     // situations because it is supposed to be called synchronously,
 143     // wxModalEventLoop depends on this (so we can't just use ON_BLOCK_EXIT or
 144     // something similar here)
 145 #if wxUSE_EXCEPTIONS
 146     for ( ;; )
 147     {
 148         try
 149         {
 150 #endif // wxUSE_EXCEPTIONS
 151
 152             // this is the event loop itself
 153             for ( ;; )
 154             {
 155                 // give them the possibility to do whatever they want
 156                 OnNextIteration();
 157
 158                 // generate and process idle events for as long as we don't
 159                 // have anything else to do
 160                 while ( !Pending() && ProcessIdle() && !m_shouldExit )
 161                     ;
 162
 163                 // if the "should exit" flag is set, the loop should terminate
 164                 // but not before processing any remaining messages so while
 165                 // Pending() returns true, do process them
 166                 if ( m_shouldExit )
 167                 {
 168                     while ( Pending() )
 169                         ProcessEvents();
 170
 171                     break;
 172                 }
 173
 174                 // a message came or no more idle processing to do, dispatch
 175                 // all the pending events and call Dispatch() to wait for the
 176                 // next message
 177                 if ( !ProcessEvents() )
 178                 {
 179                     // we got WM_QUIT
 180                     break;
 181                 }
 182             }
 183
 184 #if wxUSE_EXCEPTIONS
 185             // exit the outer loop as well
 186             break;
 187         }
 188         catch ( ... )
 189         {
 190             try
 191             {
 192                 if ( !wxTheApp || !wxTheApp->OnExceptionInMainLoop() )
 193                 {
 194                     OnExit();
 195                     break;
 196                 }
 197                 //else: continue running the event loop
 198             }
 199             catch ( ... )
 200             {
 201                 // OnException() throwed, possibly rethrowing the same
 202                 // exception again: very good, but we still need OnExit() to
 203                 // be called
 204                 OnExit();
 205                 throw;
 206             }
 207         }
 208     }
 209 #endif // wxUSE_EXCEPTIONS
 210
 211     return m_exitcode;
 212 }
 213
 214 void wxEventLoopManual::Exit(int rc)
 215 {
 216     wxCHECK_RET( IsRunning(), wxT("can't call Exit() if not running") );
 217
 218     m_exitcode = rc;
 219     m_shouldExit = true;
 220
 221     OnExit();
 222
 223     // all we have to do to exit from the loop is to (maybe) wake it up so that
 224     // it can notice that Exit() had been called
 225     //
 226     // in particular, do *not* use here calls such as PostQuitMessage() (under
 227     // MSW) which terminate the current event loop here because we're not sure
 228     // that it is going to be processed by the correct event loop: it would be
 229     // possible that another one is started and terminated by mistake if we do
 230     // this
 231     WakeUp();
 232 }
 233
 234 #endif // __WINDOWS__ || __WXMAC__ || __WXDFB__
 235