C++ 使用QGraphicsSitem和QGraphicsLineItem进行继承

我有一个继承QGraphicsItem的类，这个类需要被另一个继承QGraphicsLineItem和QGraphicsTextItem的类继承。当我这样做时，它会给我一个错误类Line没有名为setLine的成员

下面是整个场景的说明：

getEntity.h

#ifndef getEntity_H
#define getEntity_H

#include <QGraphicsItem>

class getEntity :public QObject , public QGraphicsItem
{

public:
    getEntity(QObject* parent=0) : QObject(parent) {}
    virtual ~getEntity() {}

    virtual getEntity* my_clone() { return 0; }
};


#endif // getEntity_H

cadgraphicsene.cpp

//Here it returns pointing to setLine method, when I inherit getEntity in Line class
 if (mPaintFlag)
            {
                lineItem = new Line(++id, start_p, end_p);
                lineItem->setLine(start_p.x(), start_p.y(), end_p.x(), end_p.y());

---

Line类如何正确继承getEntity？帮帮忙

为什么您要继承QObject？我使用的是信号和插槽的概念，而不是您所展示的代码。不能从QObject继承乘法。我一点也不明白你想用这段代码实现什么，但看起来你有一个设计问题。多重继承是一个非常复杂的工具。也许如果你准确地描述了你想要实现的目标，有人会指出一个更明智的方法。我想在我的图形视图中有剪切、复制和粘贴操作。我的所有实体都有不同的类，继承自Graphics Item、QGraphicsLineItem和GraphicsText Item。我正在使用getEntity类克隆所有实体的属性。要使用信号和插槽，放置

Q_对象

（就像您在类

行

）就足够了。

#include "line.h"

Line::Line(int i, QPointF p1, QPointF p2)
{
    // assigns id
    id = i;

    // set values of start point and end point of line
    start_p = p1;
    end_p = p2;
}

int Line::type() const
{
    // Enable the use of qgraphicsitem_cast with line item.
    return Type;
}

QRectF Line::boundingRect() const
{
    qreal extra = 1.0;

    // bounding rectangle for line
    return QRectF(line().p1(), QSizeF(line().p2().x() - line().p1().x(),
                                      line().p2().y() - line().p1().y()))
            .normalized()
            .adjusted(-extra, -extra, extra, extra);
}

void Line::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
                  QWidget *widget)
{
    // draws/paints the path of line
    QPen paintpen;
    painter->setRenderHint(QPainter::Antialiasing);
    paintpen.setWidth(1);

    if (isSelected())
    {
        // sets brush for end points
        painter->setBrush(Qt::SolidPattern);
        paintpen.setColor(Qt::red);
        painter->setPen(paintpen);
        painter->drawEllipse(start_p, 2, 2);
        painter->drawEllipse(end_p, 2, 2);

        // sets pen for line path
        paintpen.setStyle(Qt::DashLine);
        paintpen.setColor(Qt::black);
        painter->setPen(paintpen);
        painter->drawLine(start_p, end_p);
    }
    else
    {   painter->save();
        painter->setBrush(Qt::SolidPattern);
        paintpen.setColor(Qt::black);
        painter->setPen(paintpen);
        painter->drawEllipse(start_p, 2, 2);
        painter->drawEllipse(end_p, 2, 2);
        painter->drawLine(start_p, end_p);
        painter->restore();
    }
}

//Here it returns pointing to setLine method, when I inherit getEntity in Line class
 if (mPaintFlag)
            {
                lineItem = new Line(++id, start_p, end_p);
                lineItem->setLine(start_p.x(), start_p.y(), end_p.x(), end_p.y());