qgraphicsView中的复制粘贴操作

Question

我正在为不同的实体（如点、圆、椭圆、线和文本）实现剪切复制和粘贴操作。我已经实现了点，但是当我对其他实体遵循相同的程序时，它不起作用。不知道为什么。请帮我解决这个困惑。我的代码如下：

cadgraphicsscene.cpp

void CadGraphicsScene::cut()
{
    foreach (QGraphicsItem *item, itemList)
    {
        if (item->isSelected())
        {
            // Cuts the selected item
            removeItem(item);
            update();
        }
    }

}

void CadGraphicsScene::copy()
{
    foreach (QGraphicsItem *item, itemList)
    {
        QString str;
        // Stores the Point
        if (item->isSelected() == Point::Type)
        {
            str = QString("Point copy p(%1,%2)")
                    .arg(item->x())
                    .arg(item->y());
        }

        if (item->isSelected() == Circle::Type)
        {
            Circle *circleItem = dynamic_cast<Circle *>(item);
            str = QString("Circle copy c(%1,%2) r(%3)")
                    .arg(circleItem->center_p.x())
                    .arg(circleItem->center_p.y())
                    .arg(circleItem->radius);
        }
    }
}

void CadGraphicsScene::paste()
{
    foreach (QGraphicsItem *item, itemList)
    {
        // Calls setNewItem function
        setNewItem(item);
    }
}

void CadGraphicsScene::setNewItem(QGraphicsItem *item)
{
    static int id = 0;
    if(item->isSelected() == PointMode)
    {
        // Create a New point
        pointItem = new Point(++id);
        pointItem->setPos(item->scenePos());
        itemList.append(pointItem);
        mUndoStack->push(new CadCommandAdd(this, pointItem));
    }

    if(item->isSelected() == CircleMode)
    {
        // Create a New point
        circleItem = new Circle(id, start_p, _rad);
        itemList.append(circleItem);
        mUndoStack->push(new CadCommandAdd(this, circleItem));
    }
}

point.cpp

#include "point.h"

Point::Point(int i)
{
    // assigns id
    id = i;
}

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

QRectF Point::boundingRect() const
{
    // bounding rectangle for point
    qreal penwidth = 1;
    return QRectF(-1 - penwidth /2, -1 - penwidth/2,
                  2 + penwidth, 2 + penwidth);
}

void Point::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
                   QWidget *widget)
{
    // draws/paints the point
    QPen paintpen;
    if (isSelected())
        paintpen.setColor(Qt::red);
    else
        paintpen.setColor(Qt::black);
    paintpen.setWidth(2);
    painter->setRenderHint(QPainter::Antialiasing);
    painter->setBrush(Qt::SolidPattern);
    painter->setPen(paintpen);
    painter->drawEllipse(boundingRect());
}

circle.cpp

#include "circle.h"

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

    /* set values of center point, end point
    and calculate radius of circle */
    center_p = p1;
    end_p = p2;
    radius = qSqrt(qPow((end_p.x()-center_p.x()), 2)
                   + qPow((end_p.y()-center_p.y()), 2));
}

Circle::Circle(int i, QPointF p1, qreal rad)
{
    // assigns id
    id = i;

    /* set values of center point
       and radius of circle */
    center_p = p1;
    radius = rad;
}

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

QRectF Circle::boundingRect() const
{
    // bounding rectangle for circle
    return QRectF((center_p.x()-radius), (center_p.y()-radius),
                  (2*radius), (2*radius));
}

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

    if (isSelected())
    {
        // sets brush for center point
        painter->setBrush(Qt::SolidPattern);
        paintpen.setColor(Qt::red);
        painter->setPen(paintpen);
        painter->drawEllipse(center_p, 2, 2);

        // sets pen for circumference
        paintpen.setStyle(Qt::DashLine);
        paintpen.setColor(Qt::black);
        painter->setBrush(Qt::NoBrush);
        painter->setPen(paintpen);
        painter->drawEllipse(center_p, radius, radius);
    }
    else
    {
        painter->setBrush(Qt::SolidPattern);
        paintpen.setColor(Qt::black);
        painter->setPen(paintpen);
        painter->drawEllipse(center_p, 2, 2);
        painter->setBrush(Qt::NoBrush);
        painter->drawEllipse(center_p, radius, radius);
    }
}

Answer 1

函数QGraphicsItem::itemIsSelected表示当前是否选中该项，并返回一个布尔值。

因此，调用以下行对于检查项目类型无效：-

if (item->isSelected() == Point::Type)
if (item->isSelected() == Circle::Type)

如果要检查物品类型，请使用函数QGraphicsItem::type()