QGraphicsSimpleTextItem::paint() issue with colored SolidPen (found in Qt 5.13.2)

[lano1106]

I want to overlay text in a derived class from QChart. I have stumbled on the problem that as soon as I want to color the text, the text becomes thicker than its black counterpart:

Setting a colored SolidLine pen:

this is harder to read and this behavior did annoy me a lot. I have nailed down the problem to QGraphicsSimpleTextItem::paint() code. I did override the paint implementation to something that is braindead stupid that does what I need and it fix my issue:

class StupidSimpleText : public QGraphicsSimpleTextItem
{    
public:
    StupidSimpleText(const QString &text, QGraphicsItem *parent = NULL);
    StupidSimpleText(QGraphicsItem *parent = NULL);
    
    virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
};

void StupidSimpleText::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    Q_UNUSED(widget);

    painter->setFont(font());
    painter->setPen(pen());
    QFontMetrics metrics(font());
    QSize textSize  = metrics.size(Qt::TextSingleLine, text());
    painter->drawText(QRectF(QPointF(0,0), textSize), Qt::AlignLeft|Qt::AlignVCenter, text());
}

void LinkedChart::setInfoText(const QString &text)
{
    if (text == m_text)
        return;
    m_text = text;
    if (!m_textItem) {
        if (!text.size()) return;
//        m_textItem = scene()->addSimpleText(text, m_textFont);
        m_textItem = new StupidSimpleText(text);
        scene()->addItem(m_textItem);
        QPen magentaPen = QPen(QColor(Qt::magenta), 1);
        m_textItem->setPen(magentaPen);
        QPointF plotTopLeft = plotArea().topLeft();
        plotTopLeft.rx() += 5.0;
        plotTopLeft.ry() += 5.0;
        m_textItem->setPos(plotTopLeft);

        /*
         * Connection to reposition the graphics item when/if the plotarea is changing.
         */
        connect(this, SIGNAL(plotAreaChanged(const QRectF &)),
                this, SLOT(ourPlotAreaChanged(const QRectF &)));
    }
    m_textItem->setText(text);
}

Honestly, I don't fully understand everything QGraphicsSimpleTextItem is doing but the result of StupidSimple text is proving that something is wrong with QGraphicsSimpleTextItem::paint():

I hope this helps you guys!

[Christian Ehrlicher]

My testcase works fine for me with 5.13 and 5.14/dev:

#include <QtWidgets>

class GraphicsSimpleTextItem : public QGraphicsSimpleTextItem
{    
public:
    using QGraphicsSimpleTextItem::QGraphicsSimpleTextItem;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;
};

void GraphicsSimpleTextItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    Q_UNUSED(widget);
    painter->setFont(font());
    painter->setPen(pen());
    QFontMetrics metrics(font());
    QSize textSize  = metrics.size(Qt::TextSingleLine, text());
    painter->drawText(QRectF(QPointF(0,0), textSize), Qt::AlignLeft|Qt::AlignVCenter, text());
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QGraphicsScene scene;
    QGraphicsView view(&scene);
    view.show();
    GraphicsSimpleTextItem item("Test");
    item.setPen(QPen(QColor(Qt::magenta), 1));
    scene.addItem(&item);
    return app.exec();
}