QT触摸屏上TouchEvent 和 MouseEvent触发的顺序

项目中遇到触摸屏上 ，手长按自定义控件，MousePresssEvent 和 MouseReleaseEvent事件几乎同时触发，无法达到鼠标长按的效果，通过添加日志，QT触摸屏上TouchEvent 和 MouseEvent触发的顺序

/*
*  QT触摸屏上TouchEvent 和 MouseEvent触发的顺序
*  TouchBegin -» TouchEnd -» MouseButtonPress -» MouseButtonRelease
*  MouseButtonPress 和 MouseButtonRelease 同时触发。所以触摸屏上无法触发鼠标长按事件
*/

要实现鼠标长按的效果，需要单独处理TouchBegin 和 TouchEnd事件

项目中用的是qt4.8版本，qt5和qt6版本未验证

但是翻看qt4.8.6的源码，按照代码理解，正常的事件触发顺序应该是

TouchBegin -» MouseButtonPress -» TouchEnd -» MouseButtonRelease

bool QWidget::event(QEvent *event)
{
    Q_D(QWidget);
//这里忽略一些不相关的代码
//...
   switch (event->type()) {

    case QEvent::MouseButtonPress:
        // Don't reset input context here. Whether reset or not is
        // a responsibility of input method. reset() will be
        // called by mouseHandler() of input method if necessary
        // via mousePressEvent() of text widgets.
#if 0
        resetInputContext();
#endif
        mousePressEvent((QMouseEvent*)event);
        break;

    case QEvent::MouseButtonRelease:
        mouseReleaseEvent((QMouseEvent*)event);
        break;
//...

    case QEvent::TouchBegin:
    case QEvent::TouchUpdate:
    case QEvent::TouchEnd:
    {
#ifndef Q_WS_MAC
        QTouchEvent *touchEvent = static_cast(event);
        const QTouchEvent::TouchPoint &touchPoint = touchEvent->touchPoints().first();
        if (touchPoint.isPrimary() || touchEvent->deviceType() == QTouchEvent::TouchPad)
            break;

        // fake a mouse event!
        QEvent::Type eventType = QEvent::None;
        switch (touchEvent->type()) {
        case QEvent::TouchBegin:
            eventType = QEvent::MouseButtonPress; 
            break;
        case QEvent::TouchUpdate:
            eventType = QEvent::MouseMove;
            break;
        case QEvent::TouchEnd:
            eventType = QEvent::MouseButtonRelease;
            break;
        default:
            Q_ASSERT(!true);
            break;
        }
        if (eventType == QEvent::None)
            break;

        //这里应该回到上面的 QEvent::MouseButtonPress 和 QEvent::MouseButtonRelease的case里了，但日志打出来并不是这样
        QMouseEvent mouseEvent(eventType,
                               touchPoint.pos().toPoint(),
                               touchPoint.screenPos().toPoint(),
                               Qt::LeftButton,
                               Qt::LeftButton,
                               touchEvent->modifiers());
        (void) QApplication::sendEvent(this, &mouseEvent);
#endif // Q_WS_MAC
        break;
    }
//...

}

造成理论和实际结果不一致的原因，还没有追踪到，后面继续追踪补充