For Qt 4.6.x, how to auto-size text to fit in a specified width?

Question

Inside of my QGraphicsRectItem::paint(), I am trying to draw the name of the item within its rect(). However, for each of the different items, they can be of variable width

Answer 1

Follow function based on the answer and comment to the answer allow optimizing font size to fit text in specified rectangle:

QFont optimizeFontSizeToFitTextInRect(QPainter * painter, QRectF drawRect, QString text, int flags = Qt::TextDontClip|Qt::TextWordWrap, double goalError =  0.01, int maxIterationNumber=10){
    painter->save();

    QRect fontBoundRect;
    QFont font;
    double minError = std::numeric_limits::max();
    double error = std::numeric_limits::max();
    int iterationNumber=0;
    while((error > goalError) && (iterationNumberfontMetrics().boundingRect(drawRect.toRect(),flags, text);
        double xFactor = drawRect.width() / fontBoundRect.width();
        double yFactor = drawRect.height() / fontBoundRect.height();
        double factor;
        if (xFactor<1 && yFactor<1) {
            factor = std::min(xFactor,yFactor);
        } else if (xFactor>1 && yFactor>1) {
            factor = std::max(xFactor,yFactor);
        } else if (xFactor<1 && yFactor>1) {
            factor = xFactor;
        } else {
            factor = yFactor;
        }
        error = abs(factor-1);
        if (factor > 1 ) {
            if (error < minError) {
                minError = error;
            } else {
                break;
            }
        }
        font = painter->font();
        font.setPointSizeF(font.pointSizeF()*factor);
        painter->setFont(font);
    }
    painter->restore();

    return font;
}