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[原]Qt事件處理機制淺析

[原]Qt事件處理機制淺析

事件處理機制淺析是通過WM_ACTIVATE消息來分析的
//調用堆棧
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()  //說明1,調用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)

說明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 消息的處理
        //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個消息
            //#define WM_MOUSEFIRST 0x0200
            //#define WM_MOUSEMOVE  0x0200
        if (!qt_tabletChokeMouse) {
            result = widget->translateMouseEvent(msg);        // mouse event
        }
    }
    else {
        switch (message) {
        //message = 136 第4個消息  #define WM_SYNCPAINT 0x0088
        //message = 133,第5個消息    #define WM_NCPAINT 0x0085
        //message = 28 ,第6個消息 #define WM_ACTIVATEAPP 0x001C
        //message = 6  ,第7個消息 #define WM_ACTIVATE 0x0006 =>進入 qApp->winFocus(widget, true); //說明3
        //#define WM_NCHITTEST 0x0084 第1個消息,result = false, 進入do_default標記中的DefWindowProc處理
        //#define WM_SETCURSOR 0x0020 第2個消息,result = false, 進入do_default標記中的DefWindowProc處理
        case WM_NCHITTEST:
        case WM_SETCURSOR:
    }
    if (result)
        RETURN(false);
do_default:
    RETURN(QWinInputContext::DefWindowProc(hwnd,message,wParam,lParam))
}

//說明3
void QApplication::winFocus(QWidget *widget, bool gotFocus)
{
    if (gotFocus) {
        setActiveWindow(widget);
    }
}
void QApplication::setActiveWindow(QWidget* act)
{
    if (!previousActiveWindow) {
        QEvent appActivate(QEvent::ApplicationActivate); //關鍵是這里,appActivate 對象
        sendSpontaneousEvent(qApp, &appActivate);
    }
   for (int i = 0; i < toBeActivated.size(); ++i) {
           //這里會繼續調用
        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(),處理后,調用notify_helper繼續處理
    } 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
    //說明4:這里也是關鍵的地方
    if (sendThroughObjectEventFilters(receiver, e))
        return true;

    // deliver the event
    bool consumed = receiver->event(e); //說明5,receiver->event()調用
    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); ////說明6,最終QObject::event()調用
}

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

posted on 2013-06-27 11:10 天下閱讀(5447) 評論(0) 編輯收藏引用所屬分類: QT

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