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_shouldExit = false;
  34
  35     m_isInsideYield = false;
  36     m_eventsToProcessInsideYield = wxEVT_CATEGORY_ALL;
  37 }
  38
  39 bool wxEventLoopBase::IsMain() const
  40 {
  41     if (wxTheApp)
  42         return wxTheApp->GetMainLoop() == this;
  43     return false;
  44 }
  45
  46 /* static */
  47 void wxEventLoopBase::SetActive(wxEventLoopBase* loop)
  48 {
  49     ms_activeLoop = loop;
  50
  51     if (wxTheApp)
  52         wxTheApp->OnEventLoopEnter(loop);
  53 }
  54
  55 void wxEventLoopBase::OnExit()
  56 {
  57     if (wxTheApp)
  58         wxTheApp->OnEventLoopExit(this);
  59 }
  60
  61 void wxEventLoopBase::WakeUpIdle()
  62 {
  63     WakeUp();
  64 }
  65
  66 bool wxEventLoopBase::ProcessIdle()
  67 {
  68     return wxTheApp && wxTheApp->ProcessIdle();
  69 }
  70
  71 bool wxEventLoopBase::Yield(bool onlyIfNeeded)
  72 {
  73     if ( m_isInsideYield )
  74     {
  75         if ( !onlyIfNeeded )
  76         {
  77             wxFAIL_MSG( wxT("wxYield called recursively" ) );
  78         }
  79
  80         return false;
  81     }
  82
  83     return YieldFor(wxEVT_CATEGORY_ALL);
  84 }
  85
  86 // wxEventLoopManual is unused in the other ports
  87 #if defined(__WINDOWS__) || defined(__WXDFB__) || ( ( defined(__UNIX__) && !defined(__WXOSX__) ) && wxUSE_BASE)
  88
  89 // ============================================================================
  90 // wxEventLoopManual implementation
  91 // ============================================================================
  92
  93 wxEventLoopManual::wxEventLoopManual()
  94 {
  95     m_exitcode = 0;
  96 }
  97
  98 bool wxEventLoopManual::ProcessEvents()
  99 {
 100     // process pending wx events first as they correspond to low-level events
 101     // which happened before, i.e. typically pending events were queued by a
 102     // previous call to Dispatch() and if we didn't process them now the next
 103     // call to it might enqueue them again (as happens with e.g. socket events
 104     // which would be generated as long as there is input available on socket
 105     // and this input is only removed from it when pending event handlers are
 106     // executed)
 107     if ( wxTheApp )
 108     {
 109         wxTheApp->ProcessPendingEvents();
 110
 111         // One of the pending event handlers could have decided to exit the
 112         // loop so check for the flag before trying to dispatch more events
 113         // (which could block indefinitely if no more are coming).
 114         if ( m_shouldExit )
 115             return false;
 116     }
 117
 118     return Dispatch();
 119 }
 120
 121 int wxEventLoopManual::Run()
 122 {
 123     // event loops are not recursive, you need to create another loop!
 124     wxCHECK_MSG( !IsRunning(), -1, wxT("can't reenter a message loop") );
 125
 126     // ProcessIdle() and ProcessEvents() below may throw so the code here should
 127     // be exception-safe, hence we must use local objects for all actions we
 128     // should undo
 129     wxEventLoopActivator activate(this);
 130
 131     // we must ensure that OnExit() is called even if an exception is thrown
 132     // from inside ProcessEvents() but we must call it from Exit() in normal
 133     // situations because it is supposed to be called synchronously,
 134     // wxModalEventLoop depends on this (so we can't just use ON_BLOCK_EXIT or
 135     // something similar here)
 136 #if wxUSE_EXCEPTIONS
 137     for ( ;; )
 138     {
 139         try
 140         {
 141 #endif // wxUSE_EXCEPTIONS
 142
 143             // this is the event loop itself
 144             for ( ;; )
 145             {
 146                 // give them the possibility to do whatever they want
 147                 OnNextIteration();
 148
 149                 // generate and process idle events for as long as we don't
 150                 // have anything else to do
 151                 while ( !m_shouldExit && !Pending() && ProcessIdle() )
 152                     ;
 153
 154                 if ( m_shouldExit )
 155                     break;
 156
 157                 // a message came or no more idle processing to do, dispatch
 158                 // all the pending events and call Dispatch() to wait for the
 159                 // next message
 160                 if ( !ProcessEvents() )
 161                 {
 162                     // we got WM_QUIT
 163                     break;
 164                 }
 165             }
 166
 167             // Process the remaining queued messages, both at the level of the
 168             // underlying toolkit level (Pending/Dispatch()) and wx level
 169             // (Has/ProcessPendingEvents()).
 170             //
 171             // We do run the risk of never exiting this loop if pending event
 172             // handlers endlessly generate new events but they shouldn't do
 173             // this in a well-behaved program and we shouldn't just discard the
 174             // events we already have, they might be important.
 175             for ( ;; )
 176             {
 177                 bool hasMoreEvents = false;
 178                 if ( wxTheApp && wxTheApp->HasPendingEvents() )
 179                 {
 180                     wxTheApp->ProcessPendingEvents();
 181                     hasMoreEvents = true;
 182                 }
 183
 184                 if ( Pending() )
 185                 {
 186                     Dispatch();
 187                     hasMoreEvents = true;
 188                 }
 189
 190                 if ( !hasMoreEvents )
 191                     break;
 192             }
 193
 194 #if wxUSE_EXCEPTIONS
 195             // exit the outer loop as well
 196             break;
 197         }
 198         catch ( ... )
 199         {
 200             try
 201             {
 202                 if ( !wxTheApp || !wxTheApp->OnExceptionInMainLoop() )
 203                 {
 204                     OnExit();
 205                     break;
 206                 }
 207                 //else: continue running the event loop
 208             }
 209             catch ( ... )
 210             {
 211                 // OnException() throwed, possibly rethrowing the same
 212                 // exception again: very good, but we still need OnExit() to
 213                 // be called
 214                 OnExit();
 215                 throw;
 216             }
 217         }
 218     }
 219 #endif // wxUSE_EXCEPTIONS
 220
 221     return m_exitcode;
 222 }
 223
 224 void wxEventLoopManual::Exit(int rc)
 225 {
 226     wxCHECK_RET( IsRunning(), wxT("can't call Exit() if not running") );
 227
 228     m_exitcode = rc;
 229     m_shouldExit = true;
 230
 231     OnExit();
 232
 233     // all we have to do to exit from the loop is to (maybe) wake it up so that
 234     // it can notice that Exit() had been called
 235     //
 236     // in particular, do *not* use here calls such as PostQuitMessage() (under
 237     // MSW) which terminate the current event loop here because we're not sure
 238     // that it is going to be processed by the correct event loop: it would be
 239     // possible that another one is started and terminated by mistake if we do
 240     // this
 241     WakeUp();
 242 }
 243
 244 #endif // __WINDOWS__ || __WXMAC__ || __WXDFB__
 245