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 #include "wx/scopeguard.h"
  26 #include "wx/apptrait.h"
  27 #include "wx/private/eventloopsourcesmanager.h"
  28
  29 // ----------------------------------------------------------------------------
  30 // wxEventLoopBase
  31 // ----------------------------------------------------------------------------
  32
  33 wxEventLoopBase *wxEventLoopBase::ms_activeLoop = NULL;
  34
  35 wxEventLoopBase::wxEventLoopBase()
  36 {
  37     m_isInsideRun = false;
  38     m_shouldExit = false;
  39
  40     m_isInsideYield = false;
  41     m_eventsToProcessInsideYield = wxEVT_CATEGORY_ALL;
  42 }
  43
  44 bool wxEventLoopBase::IsMain() const
  45 {
  46     if (wxTheApp)
  47         return wxTheApp->GetMainLoop() == this;
  48     return false;
  49 }
  50
  51 /* static */
  52 void wxEventLoopBase::SetActive(wxEventLoopBase* loop)
  53 {
  54     ms_activeLoop = loop;
  55
  56     if (wxTheApp)
  57         wxTheApp->OnEventLoopEnter(loop);
  58 }
  59
  60 int wxEventLoopBase::Run()
  61 {
  62     // event loops are not recursive, you need to create another loop!
  63     wxCHECK_MSG( !IsInsideRun(), -1, wxT("can't reenter a message loop") );
  64
  65     // ProcessIdle() and ProcessEvents() below may throw so the code here should
  66     // be exception-safe, hence we must use local objects for all actions we
  67     // should undo
  68     wxEventLoopActivator activate(this);
  69
  70     // We might be called again, after a previous call to ScheduleExit(), so
  71     // reset this flag.
  72     m_shouldExit = false;
  73
  74     // Set this variable to true for the duration of this method.
  75     m_isInsideRun = true;
  76     wxON_BLOCK_EXIT_SET(m_isInsideRun, false);
  77
  78     // Finally really run the loop.
  79     return DoRun();
  80 }
  81
  82 void wxEventLoopBase::Exit(int rc)
  83 {
  84     wxCHECK_RET( IsRunning(), wxS("Use ScheduleExit() on not running loop") );
  85
  86     ScheduleExit(rc);
  87 }
  88
  89 void wxEventLoopBase::OnExit()
  90 {
  91     if (wxTheApp)
  92         wxTheApp->OnEventLoopExit(this);
  93 }
  94
  95 void wxEventLoopBase::WakeUpIdle()
  96 {
  97     WakeUp();
  98 }
  99
 100 bool wxEventLoopBase::ProcessIdle()
 101 {
 102     return wxTheApp && wxTheApp->ProcessIdle();
 103 }
 104
 105 bool wxEventLoopBase::Yield(bool onlyIfNeeded)
 106 {
 107     if ( m_isInsideYield )
 108     {
 109         if ( !onlyIfNeeded )
 110         {
 111             wxFAIL_MSG( wxT("wxYield called recursively" ) );
 112         }
 113
 114         return false;
 115     }
 116
 117     return YieldFor(wxEVT_CATEGORY_ALL);
 118 }
 119
 120 #if wxUSE_EVENTLOOP_SOURCE
 121
 122 wxEventLoopSource*
 123 wxEventLoopBase::AddSourceForFD(int fd,
 124                                 wxEventLoopSourceHandler *handler,
 125                                 int flags)
 126 {
 127     // Delegate to the event loop sources manager defined by it.
 128     wxEventLoopSourcesManagerBase* const
 129         manager = wxApp::GetValidTraits().GetEventLoopSourcesManager();
 130     wxCHECK_MSG( manager, NULL, wxS("Must have wxEventLoopSourcesManager") );
 131
 132     return manager->AddSourceForFD(fd, handler, flags);
 133 }
 134
 135 #endif // wxUSE_EVENTLOOP_SOURCE
 136
 137 // wxEventLoopManual is unused in the other ports
 138 #if defined(__WINDOWS__) || defined(__WXDFB__) || ( ( defined(__UNIX__) && !defined(__WXOSX__) ) && wxUSE_BASE)
 139
 140 // ============================================================================
 141 // wxEventLoopManual implementation
 142 // ============================================================================
 143
 144 wxEventLoopManual::wxEventLoopManual()
 145 {
 146     m_exitcode = 0;
 147 }
 148
 149 bool wxEventLoopManual::ProcessEvents()
 150 {
 151     // process pending wx events first as they correspond to low-level events
 152     // which happened before, i.e. typically pending events were queued by a
 153     // previous call to Dispatch() and if we didn't process them now the next
 154     // call to it might enqueue them again (as happens with e.g. socket events
 155     // which would be generated as long as there is input available on socket
 156     // and this input is only removed from it when pending event handlers are
 157     // executed)
 158     if ( wxTheApp )
 159     {
 160         wxTheApp->ProcessPendingEvents();
 161
 162         // One of the pending event handlers could have decided to exit the
 163         // loop so check for the flag before trying to dispatch more events
 164         // (which could block indefinitely if no more are coming).
 165         if ( m_shouldExit )
 166             return false;
 167     }
 168
 169     return Dispatch();
 170 }
 171
 172 int wxEventLoopManual::DoRun()
 173 {
 174     // we must ensure that OnExit() is called even if an exception is thrown
 175     // from inside ProcessEvents() but we must call it from Exit() in normal
 176     // situations because it is supposed to be called synchronously,
 177     // wxModalEventLoop depends on this (so we can't just use ON_BLOCK_EXIT or
 178     // something similar here)
 179 #if wxUSE_EXCEPTIONS
 180     for ( ;; )
 181     {
 182         try
 183         {
 184 #endif // wxUSE_EXCEPTIONS
 185
 186             // this is the event loop itself
 187             for ( ;; )
 188             {
 189                 // give them the possibility to do whatever they want
 190                 OnNextIteration();
 191
 192                 // generate and process idle events for as long as we don't
 193                 // have anything else to do
 194                 while ( !m_shouldExit && !Pending() && ProcessIdle() )
 195                     ;
 196
 197                 if ( m_shouldExit )
 198                     break;
 199
 200                 // a message came or no more idle processing to do, dispatch
 201                 // all the pending events and call Dispatch() to wait for the
 202                 // next message
 203                 if ( !ProcessEvents() )
 204                 {
 205                     // we got WM_QUIT
 206                     break;
 207                 }
 208             }
 209
 210             // Process the remaining queued messages, both at the level of the
 211             // underlying toolkit level (Pending/Dispatch()) and wx level
 212             // (Has/ProcessPendingEvents()).
 213             //
 214             // We do run the risk of never exiting this loop if pending event
 215             // handlers endlessly generate new events but they shouldn't do
 216             // this in a well-behaved program and we shouldn't just discard the
 217             // events we already have, they might be important.
 218             for ( ;; )
 219             {
 220                 bool hasMoreEvents = false;
 221                 if ( wxTheApp && wxTheApp->HasPendingEvents() )
 222                 {
 223                     wxTheApp->ProcessPendingEvents();
 224                     hasMoreEvents = true;
 225                 }
 226
 227                 if ( Pending() )
 228                 {
 229                     Dispatch();
 230                     hasMoreEvents = true;
 231                 }
 232
 233                 if ( !hasMoreEvents )
 234                     break;
 235             }
 236
 237 #if wxUSE_EXCEPTIONS
 238             // exit the outer loop as well
 239             break;
 240         }
 241         catch ( ... )
 242         {
 243             try
 244             {
 245                 if ( !wxTheApp || !wxTheApp->OnExceptionInMainLoop() )
 246                 {
 247                     OnExit();
 248                     break;
 249                 }
 250                 //else: continue running the event loop
 251             }
 252             catch ( ... )
 253             {
 254                 // OnException() throwed, possibly rethrowing the same
 255                 // exception again: very good, but we still need OnExit() to
 256                 // be called
 257                 OnExit();
 258                 throw;
 259             }
 260         }
 261     }
 262 #endif // wxUSE_EXCEPTIONS
 263
 264     return m_exitcode;
 265 }
 266
 267 void wxEventLoopManual::ScheduleExit(int rc)
 268 {
 269     wxCHECK_RET( IsInsideRun(), wxT("can't call ScheduleExit() if not running") );
 270
 271     m_exitcode = rc;
 272     m_shouldExit = true;
 273
 274     OnExit();
 275
 276     // all we have to do to exit from the loop is to (maybe) wake it up so that
 277     // it can notice that Exit() had been called
 278     //
 279     // in particular, do *not* use here calls such as PostQuitMessage() (under
 280     // MSW) which terminate the current event loop here because we're not sure
 281     // that it is going to be processed by the correct event loop: it would be
 282     // possible that another one is started and terminated by mistake if we do
 283     // this
 284     WakeUp();
 285 }
 286
 287 #endif // __WINDOWS__ || __WXMAC__ || __WXDFB__
 288