Preventing font scale in QGraphicsItem

Question

I am using QGraphicsTextItem to paint the text on the scene. Text is painted along the path (QGraphicsPathItem), wich is parent of my QGraphicsTextItem - so the text rotation is changed to be along the path element and is sticked to it while zooming the view. But the font size of QGraphicsTextItem is also changing while zooming the view - this is what I am trying to avoid. Of I set QGraphicsItem::ItemIgnoresTransformations flag to the QGraphicsTextItem it stops rotating while it's parent (QGraphicsPathItem) does.

I do understand that I have to re-implement QGraphicsTextItem::paint function, but I am stuck with the coordination system. Here is the code (Label class inherits public QGraphicsTextItem):

void Label::paint( QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget )
{
    // Store current position and rotation
    QPointF position = pos();
    qreal angle = rotation();

    // Store current transformation matrix
    QTransform transform = painter->worldTransform();

    // Reset painter transformation
    painter->setTransform( QTransform() );

    // Rotate painter to the stored angle
    painter->rotate( angle );

    // Draw the text
    painter->drawText( mapToScene( position ), toPlainText() );

    // Restore transformation matrix
    painter->setTransform( transform );
}

The position (and rotation) of my text on the screen is unpredictable :( What am I doing wrong? Thank you very much in advance.

Answer 1

I solved a problem this way - for drawing a line/circle/rectangle/path, which I want to be transformed, I use an appropriate QGraphicsLine/Ellipse/Rect/PathItem. For drawing the text (which I do NOT want to be transformed) I use QGraphicsSimpleTextItem. I set text's flag to ignore transormations and set it's parent to Line/Ellipse/Rect/Path item. The Line/Ellipse/Rect/Path item transforms, but text does not - this is what I wanted. I can also rotate text and set it's position. Thank you very much for answers.