QTimer在主要功能之外無法正常工作

Question

簡而言之：這段代碼位於main函數中，效果很好。 此代碼對兩個圖形元素執行交換。

        QTimer timer;
        timer.setTimerType(Qt::PreciseTimer);
        timer.setInterval(1000.0/30.0);
        timer.setSingleShot(false);

    // ====================== MOVE 4 in POS of 1 ==========================
        QPointF centre(QLineF(button1->pos(), button4->pos()).pointAt(0.5));
        QPointF positionBut4 = button4->pos();

        MyPointF centreSwap4(0, &positionBut4, &centre);
        button4->myPointF = &centreSwap4;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap4, SLOT(updateDownRight()));
        QObject::connect(&centreSwap4, SIGNAL(positionChanged()), button4, SLOT(slotMoveCircle()));

    // ====================== MOVE 4 in POS of 1 ==========================

    // ====================== MOVE 1 in POS of 4 ==========================
        QPointF positionBut1 = button1->pos();

        MyPointF centreSwap1(0, &positionBut1, &centre);
        button1->myPointF = &centreSwap1;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap1, SLOT(updateUpLeft()));
        QObject::connect(&centreSwap1, SIGNAL(positionChanged()), button1, SLOT(slotMoveCircle()));
    // ====================== MOVE 1 in POS of 4 ==========================
        timer.start();

        QTimer::singleShot(3000, Qt::PreciseTimer, &timer, SLOT(stop()));

但是，當我要將這段代碼從main中放到一個函數中時（為了縮短代碼並僅通過提供指向它們的指針來對元素執行交換），QTimer拒絕工作（說它是活動的，但未觸發超時）：

    void animateSwap(QGraphicsRectWidget *w1, QGraphicsRectWidget *w2, QTimer &timer)
    {
        QGraphicsRectWidget *button4, *button1;
        if (w1->x() > w2->x())
        {
                button4 = w2;
                button1 = w1;
        }
        else
        {
            button4 = w1;
            button1 = w2;
        }
        // ====================== MOVE w2  in POS of w1 ==========================
        QPointF centre(QLineF(button1->pos(), button4->pos()).pointAt(0.5));
        QPointF positionBut4 = button4->pos();

        MyPointF centreSwap4(0, &positionBut4, &centre);
        button4->myPointF = &centreSwap4;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap4, SLOT(updateDownRight()));
        QObject::connect(&centreSwap4, SIGNAL(positionChanged()), button4, SLOT(slotMoveCircle()));

        // ====================== !MOVE w2 in POS of w1 ==========================

        // ====================== MOVE w1 in POS of w2 ==========================
        QPointF positionBut1 = button1->pos();

        MyPointF centreSwap1(0, &positionBut1, &centre);
        button1->myPointF = &centreSwap1;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap1, SLOT(updateUpLeft()));
        QObject::connect(&centreSwap1, SIGNAL(positionChanged()), button1, SLOT(slotMoveCircle()));
        // ====================== MOVE w1 in POS of w2 ==========================
        timer.start();

        qDebug() << timer.isActive();

        QTimer::singleShot(3000, Qt::PreciseTimer, &timer, SLOT(stop()));
    }

更新：現在它可以工作了：

    void animateSwap(QGraphicsRectWidget *w1, QGraphicsRectWidget *w2, QTimer &timer, int cycles = 1)
    {
        QGraphicsRectWidget *button4, *button1;
        if (w1->x() > w2->x())
        {
                button4 = w2;
                button1 = w1;
        }
        else
        {
            button4 = w1;
            button1 = w2;
        }
        // ====================== MOVE w2  in POS of w1 ==========================
        QPointF centre(QLineF(button1->pos(), button4->pos()).pointAt(0.5));
        QPointF positionBut4 = button4->pos();

        MyPointF *centreSwap4 = new MyPointF(0, &positionBut4, &centre);
        button4->myPointF = centreSwap4;

        QObject::connect(&timer, SIGNAL(timeout()), centreSwap4, SLOT(updateDownRight()));
        QObject::connect(centreSwap4, SIGNAL(positionChanged()), button4, SLOT(slotMoveCircle()));

        // ====================== !MOVE w2 in POS of w1 ==========================

        // ====================== MOVE w1 in POS of w2 ==========================
        QPointF positionBut1 = button1->pos();

        MyPointF *centreSwap1 = new MyPointF(0, &positionBut1, &centre);
        button1->myPointF = centreSwap1;

        QObject::connect(&timer, SIGNAL(timeout()), centreSwap1, SLOT(updateUpLeft()));
        QObject::connect(centreSwap1, SIGNAL(positionChanged()), button1, SLOT(slotMoveCircle()));
        // ====================== MOVE w1 in POS of w2 ==========================
        timer.start();

        qDebug() << timer.isActive();

        QTimer::singleShot(3000 * cycles, Qt::PreciseTimer, &timer, SLOT(stop()));
    }

Answer 1

您正在將計時器的timeout（）信號連接到例如

MyPointF centreSwap1(0, &positionBut1, &centre);

這是堆棧上的一個對象，因此是函數的本地對象，並且在函數完成時被刪除。 如果刪除了其中一個對象（發送者，接收者），則Qt斷開連接，因此計時器結束時，其timeout（）信號沒有任何連接。