C++Qt实现类似Multisim软件中器件的拖拽和连接

实现类似Multisim软件中器件的拖拽和连接，可以采用Qt的Graphics View框架。Graphics View是一个强大的2D图形框架，它提供了一种方便的方式来显示和交互大量的自定义图形项。

下面是基本的实现步骤：

1. 创建一个继承自QGraphicsItem的自定义图形项类，用于表示电器元件。在该类中实现paint()方法来绘制元件的外观，以及boundingRect()方法来指定元件的边界矩形。

2. 在主窗口中创建一个QGraphicsScene对象，将其设置为Graphics View的场景，并在场景中添加自定义图形项。

3. 为每个元件实现鼠标拖拽事件的处理。在mousePressEvent()方法中记录鼠标按下的位置，并将当前元件设置为正在拖动。在mouseMoveEvent()方法中更新元件的位置，使其跟随鼠标移动。在mouseReleaseEvent()方法中检测元件是否已经放置在有效位置，如果是则添加到场景中，否则将其返回到原来的位置。

4. 实现元件之间的连接。为每个元件添加一个连接点，当用户将鼠标拖动到连接点上时，创建一个连接线条，并将其添加到场景中。

5. 在主窗口中实现鼠标拖动事件的处理。在mousePressEvent()方法中记录鼠标按下的位置，并将当前线条设置为正在拖动。在mouseMoveEvent()方法中更新线条的位置，使其跟随鼠标移动。在mouseReleaseEvent()方法中检测线条是否已经连接到有效的元件上，如果是则保持连接，否则将其删除。

以上是基本的实现步骤，可以根据实际需要进行修改和扩展。

相关问题

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。

C++Qt实现类似multisim中复制拖拽器件并且器件之间连接起来的功能的完整代码实现

以下是一个简单的示例程序，演示了如何使用Qt实现类似Multisim中复制拖拽器件并连接它们的功能。该程序包含了一个主窗口类`MainWindow`和一个自定义控件类`CircuitComponent`。

首先，我们需要在`CircuitComponent`中实现拖拽和复制功能。我们可以使用`QDrag`和`QMimeData`类来实现拖拽功能，使用`QClipboard`和`QDataStream`类来实现复制功能。下面是`CircuitComponent`的相关代码：

#include <QtWidgets>

class CircuitComponent : public QWidget
{
public:
    CircuitComponent(QWidget *parent = nullptr)
        : QWidget(parent)
    {
        setFixedSize(60, 60);
        setStyleSheet("background-color: white; border: 1px solid black;");
        setAcceptDrops(true);
    }

    void mousePressEvent(QMouseEvent *event) override
    {
        if (event->button() == Qt::LeftButton) {
            QDrag *drag = new QDrag(this);
            QMimeData *mimeData = new QMimeData;
            QByteArray data;
            QDataStream stream(&data, QIODevice::WriteOnly);
            QPoint offset = event->pos();
            stream << offset;
            mimeData->setData("application/x-circuit-component", data);
            drag->setMimeData(mimeData);
            drag->setPixmap(grab());
            drag->setHotSpot(offset);
            drag->exec(Qt::CopyAction | Qt::MoveAction);
        }
    }

    void mouseMoveEvent(QMouseEvent *event) override
    {
        if (event->buttons() & Qt::LeftButton) {
            QDrag *drag = new QDrag(this);
            QMimeData *mimeData = new QMimeData;
            QByteArray data;
            QDataStream stream(&data, QIODevice::WriteOnly);
            QPoint offset = event->pos();
            stream << offset;
            mimeData->setData("application/x-circuit-component", data);
            drag->setMimeData(mimeData);
            drag->setPixmap(grab());
            drag->setHotSpot(offset);
            drag->exec(Qt::CopyAction | Qt::MoveAction);
        }
    }

    void dragEnterEvent(QDragEnterEvent *event) override
    {
        if (event->mimeData()->hasFormat("application/x-circuit-component")) {
            event->acceptProposedAction();
        }
    }

    void dropEvent(QDropEvent *event) override
    {
        if (event->mimeData()->hasFormat("application/x-circuit-component")) {
            QByteArray data = event->mimeData()->data("application/x-circuit-component");
            QDataStream stream(&data, QIODevice::ReadOnly);
            QPoint offset;
            stream >> offset;
            CircuitComponent *component = new CircuitComponent;
            component->move(event->pos() - offset);
            component->show();
            event->setDropAction(Qt::CopyAction);
            event->accept();
        }
    }
};

接下来，我们需要在`MainWindow`中实现连接器件的功能。我们可以使用`QGraphicsScene`和`QGraphicsView`类来绘制和管理连接线，使用`QGraphicsItem`类来实现连接线和器件的图形表示。下面是`MainWindow`的相关代码：

#include <QtWidgets>

class MainWindow : public QMainWindow
{
public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        setCentralWidget(new QGraphicsView);
        scene = new QGraphicsScene(this);
        QGraphicsView *view = qobject_cast<QGraphicsView *>(centralWidget());
        view->setScene(scene);
        view->setRenderHint(QPainter::Antialiasing);
        view->setDragMode(QGraphicsView::RubberBandDrag);

        QAction *copyAction = new QAction(tr("&Copy"), this);
        connect(copyAction, &QAction::triggered, this, &MainWindow::copyComponent);
        addAction(copyAction);

        QAction *pasteAction = new QAction(tr("&Paste"), this);
        connect(pasteAction, &QAction::triggered, this, &MainWindow::pasteComponent);
        addAction(pasteAction);

        setWindowTitle(tr("Circuit Designer"));
        resize(800, 600);
    }

private:
    QGraphicsScene *scene;
    CircuitComponent *copiedComponent = nullptr;
    QGraphicsLineItem *currentLine = nullptr;
    QPointF currentStartPos;

    void copyComponent()
    {
        if (!scene->selectedItems().isEmpty()) {
            QGraphicsItem *item = scene->selectedItems().first();
            if (item->type() == CircuitComponent::Type) {
                copiedComponent = qgraphicsitem_cast<CircuitComponent *>(item);
            }
        }
    }

    void pasteComponent()
    {
        if (copiedComponent) {
            CircuitComponent *component = new CircuitComponent;
            component->move(mapFromGlobal(QCursor::pos()));
            component->show();
            scene->addItem(component);
        }
    }

    void mousePressEvent(QMouseEvent *event) override
    {
        if (event->button() == Qt::LeftButton) {
            QGraphicsItem *item = scene->itemAt(event->pos(), QTransform());
            if (item && item->type() == CircuitComponent::Type) {
                currentStartPos = item->mapToScene(item->boundingRect().center());
                currentLine = new QGraphicsLineItem(QLineF(currentStartPos, event->scenePos()));
                currentLine->setPen(QPen(Qt::black, 2));
                scene->addItem(currentLine);
            }
        }
    }

    void mouseMoveEvent(QMouseEvent *event) override
    {
        if (currentLine) {
            currentLine->setLine(QLineF(currentStartPos, event->scenePos()));
        }
    }

    void mouseReleaseEvent(QMouseEvent *event) override
    {
        if (currentLine) {
            QGraphicsItem *startItem = scene->itemAt(currentStartPos, QTransform());
            QGraphicsItem *endItem = scene->itemAt(event->scenePos(), QTransform());
            if (startItem && startItem->type() == CircuitComponent::Type &&
                endItem && endItem->type() == CircuitComponent::Type &&
                startItem != endItem) {
                QPointF start = startItem->mapToScene(startItem->boundingRect().center());
                QPointF end = endItem->mapToScene(endItem->boundingRect().center());
                QGraphicsLineItem *lineItem = new QGraphicsLineItem(QLineF(start, end));
                lineItem->setPen(QPen(Qt::black, 2));
                scene->addItem(lineItem);
            }
            delete currentLine;
            currentLine = nullptr;
        }
    }
};

最后，在`main()`函数中创建`MainWindow`并运行程序：

#include <QtWidgets>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MainWindow window;
    window.show();
    return app.exec();
}

这样，我们就完成了一个简单的类似Multisim的电路设计程序。完整代码可以在下面找到：

#include <QtWidgets>

class CircuitComponent : public QWidget
{
public:
    CircuitComponent(QWidget *parent = nullptr)
        : QWidget(parent)
    {
        setFixedSize(60, 60);
        setStyleSheet("background-color: white; border: 1px solid black;");
        setAcceptDrops(true);
    }

    void mousePressEvent(QMouseEvent *event) override
    {
        if (event->button() == Qt::LeftButton) {
            QDrag *drag = new QDrag(this);
            QMimeData *mimeData = new QMimeData;
            QByteArray data;
            QDataStream stream(&data, QIODevice::WriteOnly);
            QPoint offset = event->pos();
            stream << offset;
            mimeData->setData("application/x-circuit-component", data);
            drag->setMimeData(mimeData);
            drag->setPixmap(grab());
            drag->setHotSpot(offset);
            drag->exec(Qt::CopyAction | Qt::MoveAction);
        }
    }

    void mouseMoveEvent(QMouseEvent *event) override
    {
        if (event->buttons() & Qt::LeftButton) {
            QDrag *drag = new QDrag(this);
            QMimeData *mimeData = new QMimeData;
            QByteArray data;
            QDataStream stream(&data, QIODevice::WriteOnly);
            QPoint offset = event->pos();
            stream << offset;
            mimeData->setData("application/x-circuit-component", data);
            drag->setMimeData(mimeData);
            drag->setPixmap(grab());
            drag->setHotSpot(offset);
            drag->exec(Qt::CopyAction | Qt::MoveAction);
        }
    }

    void dragEnterEvent(QDragEnterEvent *event) override
    {
        if (event->mimeData()->hasFormat("application/x-circuit-component")) {
            event->acceptProposedAction();
        }
    }

    void dropEvent(QDropEvent *event) override
    {
        if (event->mimeData()->hasFormat("application/x-circuit-component")) {
            QByteArray data = event->mimeData()->data("application/x-circuit-component");
            QDataStream stream(&data, QIODevice::ReadOnly);
            QPoint offset;
            stream >> offset;
            CircuitComponent *component = new CircuitComponent;
            component->move(event->pos() - offset);
            component->show();
            event->setDropAction(Qt::CopyAction);
            event->accept();
        }
    }
};

class MainWindow : public QMainWindow
{
public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        setCentralWidget(new QGraphicsView);
        scene = new QGraphicsScene(this);
        QGraphicsView *view = qobject_cast<QGraphicsView *>(centralWidget());
        view->setScene(scene);
        view->setRenderHint(QPainter::Antialiasing);
        view->setDragMode(QGraphicsView::RubberBandDrag);

        QAction *copyAction = new QAction(tr("&Copy"), this);
        connect(copyAction, &QAction::triggered, this, &MainWindow::copyComponent);
        addAction(copyAction);

        QAction *pasteAction = new QAction(tr("&Paste"), this);
        connect(pasteAction, &QAction::triggered, this, &MainWindow::pasteComponent);
        addAction(pasteAction);

        setWindowTitle(tr("Circuit Designer"));
        resize(800, 600);
    }

private:
    QGraphicsScene *scene;
    CircuitComponent *copiedComponent = nullptr;
    QGraphicsLineItem *currentLine = nullptr;
    QPointF currentStartPos;

    void copyComponent()
    {
        if (!scene->selectedItems().isEmpty()) {
            QGraphicsItem *item = scene->selectedItems().first();
            if (item->type() == CircuitComponent::Type) {
                copiedComponent = qgraphicsitem_cast<CircuitComponent *>(item);
            }
        }
    }

    void pasteComponent()
    {
        if (copiedComponent) {
            CircuitComponent *component = new CircuitComponent;
            component->move(mapFromGlobal(QCursor::pos()));
            component->show();
            scene->addItem(component);
        }
    }

    void mousePressEvent(QMouseEvent *event) override
    {
        if (event->button() == Qt::LeftButton) {
            QGraphicsItem *item = scene->itemAt(event->pos(), QTransform());
            if (item && item->type() == CircuitComponent::Type) {
                currentStartPos = item->mapToScene(item->boundingRect().center());
                currentLine = new QGraphicsLineItem(QLineF(currentStartPos, event->scenePos()));
                currentLine->setPen(QPen(Qt::black, 2));
                scene->addItem(currentLine);
            }
        }
    }

    void mouseMoveEvent(QMouseEvent *event) override
    {
        if (currentLine) {
            currentLine->setLine(QLineF(currentStartPos, event->scenePos()));
        }
    }

    void mouseReleaseEvent(QMouseEvent *event) override
    {
        if (currentLine) {
            QGraphicsItem *startItem = scene->itemAt(currentStartPos, QTransform());
            QGraphicsItem *endItem = scene->itemAt(event->scenePos(), QTransform());
            if (startItem && startItem->type() == CircuitComponent::Type &&
                endItem && endItem->type() == CircuitComponent::Type &&
                startItem != endItem) {
                QPointF start = startItem->mapToScene(startItem->boundingRect().center());
                QPointF end = endItem->mapToScene(endItem->boundingRect().center());
                QGraphicsLineItem *lineItem = new QGraphicsLineItem(QLineF(start, end));
                lineItem->setPen(QPen(Qt::black, 2));
                scene->addItem(lineItem);
            }
            delete currentLine;
            currentLine = nullptr;
        }
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    MainWindow window;
    window.show();
    return app.exec();
}