Tiled image in QGraphicsView foreground

Question

I'm working on a Qt application made with a main QGraphicsView.

This view can show and switch between differents QgraphicsScenes. This application needs to always have an overlay in front of each scenes, so the best way to do this overlay is by setForegroundBrush() method of QGraphicsView.

But my overlay is a tiled-image, where I could edit the opacity and the scale of the source image.

Here's the code written in my QGraphicsView class constructor :

QString imgPath("path/to/image.png");
QPixmap map(imgPath);
QPainter painter(this);
QRectF zone(0,0,map.width(),map.height());
painter.drawPixmap(zone,map,zone);
QBrush brush = painter.brush();
brush.setStyle(Qt::TexturePattern);
setForegroundBrush(brush);

But doesn't work, nothing is shown. I tested a simple QBrush with a QPixmap and works fine, but I need to use QPainter to be able to edit the opacity of my image.

Answer 1

Finally I think the easiest way to have a tiled image in QGraphicsView foreground is by reimplmenting the drawForeground(QPainter *painter, const QRectF &rect).

void Frontend::drawForeground(QPainter *painter, const QRectF &rect){
    float alpha = 0.15;
    float scale = 2;
    QString imgPath("path/to/image.png");
    QPixmap img(imgPath);
    painter->scale(scale,scale);
    painter->setOpacity(alpha);
    painter->drawTiledPixmap(rect,img);
}