Painting the inside of a shape in QGraphicsItem

[wysota]

There is no need for any extra graphics items.

#include <QtGui>
 
 
class View : public QGraphicsView {
public:
    View() : QGraphicsView(){}
protected:
    void mousePressEvent(QMouseEvent *event) {
        foreach(QGraphicsItem *i, scene()->items())
            i->setSelected(false);
        m_path.setFillRule(Qt::WindingFill);
        m_path.moveTo(event->posF());
    }
    void mouseMoveEvent(QMouseEvent *event) {
        m_path.lineTo(event->posF());
        viewport()->update();
    }
    void mouseReleaseEvent(QMouseEvent *event) {
        m_path.closeSubpath();
 
        QList<QGraphicsItem*> it = scene()->items(mapToScene(m_path));
        foreach(QGraphicsItem *i, it)
            i->setSelected(true);
        viewport()->update();
        m_path = QPainterPath();
 
    }
 
void paintEvent(QPaintEvent *event) {
    QGraphicsView::paintEvent(event);
    if(m_path.isEmpty())
        return;
    QPainter p(viewport());
    QPen pen(QColor(Qt::red));
    pen.setWidth(4);
    p.setPen(pen);
    p.setRenderHint(QPainter::Antialiasing);
    p.setBrush(QColor(255,0,0,100));
 
    p.drawPath(m_path);
}
 
private:
    QPainterPath m_path;
};
 
int main(int argc, char **argv) {
    QApplication app(argc, argv);
    QGraphicsScene scene;
    qsrand(QDateTime::currentDateTime().toTime_t());
    for(int i=0;i<50;i++) {
        QColor c(qrand() % 255, qrand() % 255, qrand() % 255);
        scene.addEllipse(qrand() % 500, qrand() % 500, qrand() % 100, qrand() % 100, c, c)->setFlag(QGraphicsItem::ItemIsSelectable);
    }
    View view;
    view.setRenderHint(QPainter::Antialiasing);
    view.setScene(&scene);
    view.show();
    return app.exec();
}

#include <QtGui>


class View : public QGraphicsView {
public:
    View() : QGraphicsView(){}
protected:
    void mousePressEvent(QMouseEvent *event) {
        foreach(QGraphicsItem *i, scene()->items())
            i->setSelected(false);
        m_path.setFillRule(Qt::WindingFill);
        m_path.moveTo(event->posF());
    }
    void mouseMoveEvent(QMouseEvent *event) {
        m_path.lineTo(event->posF());
        viewport()->update();
    }
    void mouseReleaseEvent(QMouseEvent *event) {
        m_path.closeSubpath();

        QList<QGraphicsItem*> it = scene()->items(mapToScene(m_path));
        foreach(QGraphicsItem *i, it)
            i->setSelected(true);
        viewport()->update();
        m_path = QPainterPath();

    }

void paintEvent(QPaintEvent *event) {
    QGraphicsView::paintEvent(event);
    if(m_path.isEmpty())
        return;
    QPainter p(viewport());
    QPen pen(QColor(Qt::red));
    pen.setWidth(4);
    p.setPen(pen);
    p.setRenderHint(QPainter::Antialiasing);
    p.setBrush(QColor(255,0,0,100));

    p.drawPath(m_path);
}

private:
    QPainterPath m_path;
};

int main(int argc, char **argv) {
    QApplication app(argc, argv);
    QGraphicsScene scene;
    qsrand(QDateTime::currentDateTime().toTime_t());
    for(int i=0;i<50;i++) {
        QColor c(qrand() % 255, qrand() % 255, qrand() % 255);
        scene.addEllipse(qrand() % 500, qrand() % 500, qrand() % 100, qrand() % 100, c, c)->setFlag(QGraphicsItem::ItemIsSelectable);
    }
    View view;
    view.setRenderHint(QPainter::Antialiasing);
    view.setScene(&scene);
    view.show();
    return app.exec();
}

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