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();
}