C++Qt实现类似Multisim软件中器件的拖拽和连接的具体代码

下面是一个简单的示例，展示如何使用C++和Qt实现类似Multisim软件中器件的拖拽和连接。注意，这只是一个基本示例，可能需要进行更多的细节调整和优化，以适应您的具体需求。

首先，我们需要创建两个自定义QWidget，一个代表器件，另一个代表连接线。我们将称它们为ComponentWidget和ConnectionWidget。

class ComponentWidget : public QWidget {
    Q_OBJECT

public:
    explicit ComponentWidget(QWidget *parent = nullptr);

signals:
    void componentMoved(ComponentWidget *component, const QPoint &newPosition);

protected:
    void mousePressEvent(QMouseEvent *event) override;
    void mouseMoveEvent(QMouseEvent *event) override;

private:
    QPoint m_dragStartPosition;
};

class ConnectionWidget : public QWidget {
    Q_OBJECT

public:
    explicit ConnectionWidget(QWidget *parent = nullptr);

    void setStartPoint(const QPoint &point);
    void setEndPoint(const QPoint &point);

protected:
    void paintEvent(QPaintEvent *event) override;

private:
    QPoint m_startPoint;
    QPoint m_endPoint;
};

ComponentWidget中实现了拖拽功能，当用户按下鼠标左键时，将记录下鼠标相对于组件窗口左上角的位置。当用户移动鼠标时，将计算出鼠标的新位置并发出componentMoved信号。

ComponentWidget::ComponentWidget(QWidget *parent)
    : QWidget(parent) {
    setFixedSize(50, 50);
    setStyleSheet("background-color: beige; border-radius: 10px;");
}

void ComponentWidget::mousePressEvent(QMouseEvent *event) {
    if (event->button() == Qt::LeftButton) {
        m_dragStartPosition = event->pos();
    }
}

void ComponentWidget::mouseMoveEvent(QMouseEvent *event) {
    if (event->buttons() & Qt::LeftButton) {
        QPoint newPos = mapToParent(event->pos() - m_dragStartPosition);
        emit componentMoved(this, newPos);
    }
}

ConnectionWidget将显示两个端点之间的连接线。我们将使用QPainter来绘制直线。

ConnectionWidget::ConnectionWidget(QWidget *parent)
    : QWidget(parent) {
    setAttribute(Qt::WA_TransparentForMouseEvents);
}

void ConnectionWidget::setStartPoint(const QPoint &point) {
    m_startPoint = point;
    update();
}

void ConnectionWidget::setEndPoint(const QPoint &point) {
    m_endPoint = point;
    update();
}

void ConnectionWidget::paintEvent(QPaintEvent *event) {
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.drawLine(m_startPoint, m_endPoint);
}

现在，我们需要一个主窗口来包含这些自定义QWidget，并实现器件拖拽和连接的逻辑。

class MainWindow : public QMainWindow {
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);

protected:
    void mousePressEvent(QMouseEvent *event) override;
    void mouseMoveEvent(QMouseEvent *event) override;
    void mouseReleaseEvent(QMouseEvent *event) override;

private slots:
    void onComponentMoved(ComponentWidget *component, const QPoint &newPosition);

private:
    ComponentWidget *m_component;
    ConnectionWidget *m_connection;
    bool m_isConnecting;
    QPoint m_startPoint;
};

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , m_isConnecting(false) {
    m_component = new ComponentWidget(this);
    m_component->move(50, 50);

    m_connection = new ConnectionWidget(this);
    m_connection->setStartPoint(m_component->mapToParent(m_component->rect().center()));

    connect(m_component, &ComponentWidget::componentMoved, this, &MainWindow::onComponentMoved);
}

void MainWindow::mousePressEvent(QMouseEvent *event) {
    if (event->button() == Qt::LeftButton) {
        if (m_component->geometry().contains(event->pos())) {
            m_isConnecting = true;
            m_startPoint = m_component->mapToParent(m_component->rect().center());
        }
    }
}

void MainWindow::mouseMoveEvent(QMouseEvent *event) {
    if (m_isConnecting) {
        m_connection->setEndPoint(event->pos());
    }
}

void MainWindow::mouseReleaseEvent(QMouseEvent *event) {
    if (m_isConnecting) {
        m_isConnecting = false;

        for (QWidget *widget : QApplication::topLevelWidgets()) {
            if (widget == this) {
                continue;
            }

            if (widget->geometry().contains(event->globalPos())) {
                QPoint endPoint = widget->mapFromGlobal(event->globalPos());
                endPoint = widget->mapToParent(endPoint);
                endPoint = m_connection->parentWidget()->mapFrom(widget, endPoint);

                m_connection->setEndPoint(endPoint);
                break;
            }
        }

        m_connection = new ConnectionWidget(this);
        m_connection->setStartPoint(m_component->mapToParent(m_component->rect().center()));
    }
}

void MainWindow::onComponentMoved(ComponentWidget *component, const QPoint &newPosition) {
    if (m_isConnecting && component == m_component) {
        m_connection->setStartPoint(newPosition);
    }
}

在这个主窗口中，我们创建了一个ComponentWidget和一个ConnectionWidget。我们还添加了3个事件处理程序：鼠标按下，鼠标移动和鼠标释放。当用户按下鼠标左键时，我们检查是否需要开始连接器件。当用户移动鼠标时，我们更新连接器件的终点。当用户释放鼠标左键时，我们检查鼠标在哪个QWidget上，并将连接线的终点设置为该QWidget上的点。我们还在onComponentMoved槽中处理组件移动事件，以便在连接器件时更新连接线的起点。

这只是一个简单的示例，您可以根据自己的需求进行修改和扩展。