[原]Qt事件处理机制浅析

[原]Qt事件处理机制浅析

 

[原]Qt事件处理机制浅析
    
事件处理机制浅析是通过WM_ACTIVATE消息来分析的
// 调用堆栈
WinMainCRTStartup()  
__tmainCRTStartup() 
WinMain()  
main( int  argc = 1 ,  char   **  argv)  
QtGuid4.dll ! QApplication::exec()  
QtCored4.dll ! QCoreApplication::exec()  
QtCored4.dll ! QEventLoop::exec()  
QtCored4.dll ! QEventLoop::processEvents()  
QtGuid4.dll ! QGuiEventDispatcherWin32::processEvents() 
QtCored4.dll ! QEventDispatcherWin32::processEvents()  
user32.dll ! _PeekMessageW@ 20 ()   // 说明1,调用PeekMessage,非阻塞的取消息!
QtGuid4.dll ! QtWndProc(HWND__  *  hwnd, unsigned  int  message = 6 , unsigned  int  wParam = 2 ,  long  lParam = 0 )   // 即 WM_ACTIVATE 消息
QtGuid4.dll ! QApplication::winFocus(QWidget  *  widget,  bool  gotFocus = true )  
QtGuid4.dll ! QApplication::setActiveWindow(QWidget  *  act) 
QtCored4.dll ! QCoreApplication::sendSpontaneousEvent(QObject  *  receiver, QEvent  *   event )  
QtCored4.dll ! QCoreApplication::notifyInternal(QObject  *  receiver, QEvent  *   event )  
QtGuid4.dll ! QApplication::notify(QObject  *  receiver, QEvent  *  e)  
QtGuid4.dll ! QApplicationPrivate::notify_helper(QObject  *  receiver, QEvent  *  e) 
QtGuid4.dll ! QApplication:: event (QEvent  *  e)  
QtCored4.dll ! QCoreApplication:: event (QEvent  *  e)  
QtCored4.dll ! QObject:: event (QEvent  *  e) 


说明2:
//  QtWndProc() receives all messages from the main event loop
extern   " C "  LRESULT QtWndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
     switch  (message) {
         // case 消息的处理
         // 1538行->1670行 
    }
     if  ( ! widget)
        widget  =  (QETWidget * )QWidget::find(hwnd);
     if  ( ! widget)                                 //  don't know this widget
         goto  do_default;
        
     if  (qt_is_translatable_mouse_event(message)) { 
             // message=512 第3个消息
             // #define WM_MOUSEFIRST 0x0200
             // #define WM_MOUSEMOVE  0x0200
         if  ( ! qt_tabletChokeMouse) {
            result  =  widget -> translateMouseEvent(msg);         //  mouse event
        }            
    }
     else  {
         switch  (message) {    
         // message = 136 第4个消息  #define WM_SYNCPAINT 0x0088
         // message = 133,第5个消息    #define WM_NCPAINT 0x0085 
         // message = 28 ,第6个消息 #define WM_ACTIVATEAPP 0x001C
         // message = 6  ,第7个消息 #define WM_ACTIVATE 0x0006 =>进入 qApp->winFocus(widget, true);  // 说明3    
         // #define WM_NCHITTEST 0x0084 第1个消息,result = false, 进入do_default标记中的DefWindowProc处理
         // #define WM_SETCURSOR 0x0020 第2个消息,result = false, 进入do_default标记中的DefWindowProc处理
         case  WM_NCHITTEST: 
         case  WM_SETCURSOR: 
    }
     if  (result)
        RETURN( false );
do_default:
    RETURN(QWinInputContext::DefWindowProc(hwnd,message,wParam,lParam))            
}

// 说明3
void  QApplication::winFocus(QWidget  * widget,  bool  gotFocus)
{
     if  (gotFocus) {
        setActiveWindow(widget);
    }
}    
void  QApplication::setActiveWindow(QWidget *  act)
{    
     if  ( ! previousActiveWindow) {
        QEvent appActivate(QEvent::ApplicationActivate);  // 关键是这里,appActivate 对象
        sendSpontaneousEvent(qApp,  & appActivate);
    }
    for  ( int  i  =   0 ; i  <  toBeActivated.size();  ++ i) {  
            // 这里会继续调用
        QWidget  * w  =  toBeActivated.at(i);
        sendSpontaneousEvent(w,  & windowActivate);
        sendSpontaneousEvent(w,  & activationChange);
    } 
    
}
inline  bool  QCoreApplication::sendSpontaneousEvent(QObject  * receiver, QEvent  * event )
{ 
     if  ( event )  event -> spont  =   true ;  return  self  ?  self -> notifyInternal(receiver,  event ) :  false ; 
}

/* !
  \internal
  This function is here to make it possible for Qt extensions to
  hook into event notification without subclassing QApplication
*/
bool  QCoreApplication::notifyInternal(QObject  * receiver, QEvent  * event )
{
     //  Make it possible for Qt Jambi and QSA to hook into events even
     //  though QApplication is subclassed
     bool  result  =   false ;
     void   * cbdata[]  =  { receiver,  event ,  & result };
     if  (QInternal::activateCallbacks(QInternal::EventNotifyCallback, cbdata)) {
         return  result;
    }

     //  Qt enforces the rule that events can only be sent to objects in
     //  the current thread, so receiver->d_func()->threadData is
     //  equivalent to QThreadData::current(), just without the function
     //  call overhead.
    QObjectPrivate  * d  =  receiver -> d_func();
    QThreadData  * threadData  =  d -> threadData;
     ++ threadData -> loopLevel;

     bool  returnValue;
    QT_TRY {
        returnValue  =  notify(receiver,  event );   // 大名鼎鼎的notify(),处理后,调用notify_helper继续处理
    } QT_CATCH () {
         -- threadData -> loopLevel;
        QT_RETHROW;
    }
     -- threadData -> loopLevel;
     return  returnValue;
}



bool  QApplication::notify(QObject  * receiver, QEvent  * e)
{
     //
     //  walk through parents and check for gestures
     if  (d -> gestureManager) {
         switch  (e -> type()) {
         case  QEvent::Paint:
         case  QEvent::DynamicPropertyChange:
         case  QEvent::NetworkReplyUpdated:
         //
             break ;
         default :
             if  (receiver -> isWidgetType()) {
                 if  (d -> gestureManager -> filterEvent(static_cast < QWidget  *> (receiver), e))
                     return   true ;
            }  else  {
                 //  a special case for events that go to QGesture objects.
                 //  We pass the object to the gesture manager and it'll figure
                 //  out if it's QGesture or not.
                 if  (d -> gestureManager -> filterEvent(receiver, e))
                     return   true ;
            }
        }
    }

     //  User input and window activation makes tooltips sleep
     switch  (e -> type()) {
     case  QEvent::Wheel:
     case  QEvent::ActivationChange:
     //
     default :
        res  =  d -> notify_helper(receiver, e);
         break ;
    }
     return  res;
}


bool  QApplicationPrivate::notify_helper(QObject  * receiver, QEvent  *  e)
{
     //  send to all application event filters
     if  (sendThroughApplicationEventFilters(receiver, e))
         return   true ;

     if  (receiver -> isWidgetType()) {
        QWidget  * widget  =  static_cast < QWidget  *> (receiver);
         // .
         if  (QLayout  * layout = widget -> d_func() -> layout) {
            layout -> widgetEvent(e);
        }
    }

     //  send to all receiver event filters 
     // 说明4:这里也是关键的地方
     if  (sendThroughObjectEventFilters(receiver, e))
         return   true ;

     //  deliver the event
     bool  consumed  =  receiver -> event (e);  // 说明5,receiver->event()调用
    e -> spont  =   false ;
     return  consumed;
}

bool  QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject  * receiver, QEvent  * event )
{
    Q_Q(QCoreApplication);
     if  (receiver  !=  q) {
         for  ( int  i  =   0 ; i  <  receiver -> d_func() -> eventFilters.size();  ++ i) {
            register QObject  * obj  =  receiver -> d_func() -> eventFilters.at(i);
             if  ( ! obj)
                 continue ;
             if  (obj -> d_func() -> threadData  !=  receiver -> d_func() -> threadData) {
                qWarning( " QCoreApplication: Object event filter cannot be in a different thread. " );
                 continue ;
            }
             if  (obj -> eventFilter(receiver,  event ))
                 return   true ;
        }
    }
     return   false ;
}


bool  QCoreApplicationPrivate::sendThroughApplicationEventFilters(QObject  * receiver, QEvent  * event )
{
     if  (receiver -> d_func() -> threadData  ==   this -> threadData) {
         //  application event filters are only called for objects in the GUI thread
         for  ( int  i  =   0 ; i  <  eventFilters.size();  ++ i) {
            register QObject  * obj  =  eventFilters.at(i);
             if  ( ! obj)
                 continue ;
             if  (obj -> d_func() -> threadData  !=  threadData) {
                qWarning( " QCoreApplication: Application event filter cannot be in a different thread. " );
                 continue ;
            }
             if  (obj -> eventFilter(receiver,  event ))
                 return   true ;
        }
    }
     return   false ;
}
bool  QApplication:: event (QEvent  * e)
{
    Q_D(QApplication);
     if (e -> type()  ==  QEvent::Close) {
        QCloseEvent  * ce  =  static_cast < QCloseEvent *> (e);
        ce -> accept();
        closeAllWindows();

        QWidgetList list  =  topLevelWidgets();
         for  ( int  i  =   0 ; i  <  list.size();  ++ i) {
            QWidget  * w  =  list.at(i);
             if  (w -> isVisible()  &&   ! (w -> windowType()  ==  Qt::Desktop)  &&   ! (w -> windowType()  ==  Qt::Popup)  &&
                 ( ! (w -> windowType()  ==  Qt::Dialog)  ||   ! w -> parentWidget())) {
                ce -> ignore();
                 break ;
            }
        }
         if  (ce -> isAccepted()) {
             return   true ;
        }  else  {
        }
    }  else   if (e -> type()  ==  QEvent::LanguageChange) {
        QWidgetList list  =  topLevelWidgets();
         for  ( int  i  =   0 ; i  <  list.size();  ++ i) {
            QWidget  * w  =  list.at(i);
             if  ( ! (w -> windowType()  ==  Qt::Desktop))
                postEvent(w,  new  QEvent(QEvent::LanguageChange));
        }
    }  else   if  (e -> type()  ==  QEvent::Timer) {
        QTimerEvent  * te  =  static_cast < QTimerEvent *> (e);
        Q_ASSERT(te  !=   0 );
         if  (te -> timerId()  ==  d -> toolTipWakeUp.timerId()) {
            d -> toolTipWakeUp.stop();
             if  (d -> toolTipWidget) {
                QWidget  * w  =  d -> toolTipWidget -> window();
                 //  show tooltip if WA_AlwaysShowToolTips is set, or if
                 //  any ancestor of d->toolTipWidget is the active
                 //  window
                 bool  showToolTip  =  w -> testAttribute(Qt::WA_AlwaysShowToolTips);
                 while  (w  &&   ! showToolTip) {
                    showToolTip  =  w -> isActiveWindow();
                    w  =  w -> parentWidget();
                    w  =  w  ?  w -> window() :  0 ;
                }
                 if  (showToolTip) {
                    QHelpEvent e(QEvent::ToolTip, d -> toolTipPos, d -> toolTipGlobalPos);
                    QApplication::sendEvent(d -> toolTipWidget,  & e);
                     if  (e.isAccepted())
                        d -> toolTipFallAsleep.start( 2000 ,  this );
                }
            }
        }  else   if  (te -> timerId()  ==  d -> toolTipFallAsleep.timerId()) {
            d -> toolTipFallAsleep.stop();
        }
    }
     return  QCoreApplication:: event (e);  /// /说明6,最终QObject::event()调用
}

bool  QCoreApplication:: event (QEvent  * e)
{
     if  (e -> type()  ==  QEvent::Quit) {
        quit();
         return   true ;
    }
     return  QObject:: event (e);
}