QGraphicsScene中没有显示任何内容

时间:2011-06-14 08:46:00

标签: c++ qt qgraphicsview qgraphicsitem

我正在尝试使用qgraphicsview qgraphicsitem创建一个像国际象棋一样的场景。

我正在关注尝试创建它的官方示例,但没有显示任何内容。代码非常相似。首先,我想知道的是我的Cell课程。所以我只想画一个矩形。但没有任何表现。下面是我的代码,有人可以帮助我。我在Windows 7上使用Qt 4.7

Cell.h

class Cell : public QGraphicsItem
{
    //Q_OBJECT;

public:
    Cell(const QColor &color,int x, int y);
    QRectF boundingRect() const;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
private:
    int x,y;
public:
    QColor color;
protected:
     void mousePressEvent(QGraphicsSceneMouseEvent *event);
};

Cell.cpp

Cell::Cell(const QColor &color, int x, int y)
{
    this->x=x;
    this->y=y;
    this->color=color;
    setAcceptedMouseButtons(Qt::LeftButton);

}

QRectF Cell::boundingRect() const
{
    return QRectF(0,0,30,15);
}

void Cell::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{


    QBrush b=painter->brush();
    painter->setBrush(QColor::fromRgb(0,0,255));
    painter->drawRect(0,0,30,15);
    painter->fillRect(this->boundingRect(),QColor::fromRgb(0,0,255));
    painter->setBrush(b);
    return;
}

void Cell::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
    QGraphicsItem::mouseMoveEvent(event);
    this->color=QColor::fromRgb(0,0,0);
    update();

}

view.h

class View : public QFrame
{
    Q_OBJECT

public:
    QGraphicsView *getview() const;

public:
    View(QWidget *parent);
private:
    QGraphicsView *graphicsView;
};

view.cpp

View::View(QWidget *parent)
    :QFrame(parent)
{
    graphicsView = new QGraphicsView;
    graphicsView->setRenderHint(QPainter::Antialiasing, false);
    graphicsView->setOptimizationFlags(QGraphicsView::DontSavePainterState);
    graphicsView->setViewportUpdateMode(QGraphicsView::SmartViewportUpdate);
}

QGraphicsView *View::getview() const
{
    return graphicsView;
}

mainwindow.h

class MainWindow : public QWidget
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    void populateScene();

    QGraphicsScene *scene;
};

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QWidget(parent)
{
    populateScene();
    View *v=new View(0);
    v->getview()->setScene(scene);

    QHBoxLayout *layout = new QHBoxLayout;
    layout->addWidget(v);
    setLayout(layout);
}

MainWindow::~MainWindow()
{
}

void MainWindow::populateScene()
{
    scene=new QGraphicsScene();
    for(int x=0;x<30;x++)
    {
        for(int y=0;y<20;y++)
        {
            QGraphicsItem *item=new Cell(QColor::fromRgb(0,255,255),30,15);
            item->setPos(QPointF(30,15));
            scene->addItem(item);
        }
    }
}

的main.cpp

QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();

1 个答案:

答案 0 :(得分:2)

您的QFrame不“拥有”您的QGraphicsView。因此没有理由在其中显示视图。

只需替换

graphicsView = new QGraphicsView;

with:

graphicsView = new QGraphicsView(this);

并且不要忘记调整窗口大小,(或在代码中设置最小大小)否则,您可能认为它不起作用=)