Make lines on scene always the same size?

[darktorres]

I have made a image viewer that can make lines over the images but if the image have high resolution the lines become small (like in the images uploaded, the cat image as big lines and the macaw image has tiny lines). Is there a way to make the lines with a fixed size regardless of the scene size?

My scene is set like:

item[0]->setPixmap(image.at(img)->getPixmap(0));
scene[0]->setSceneRect(0, 0, item[0]->pixmap().width(), item[0]->pixmap().height());
ui->graphicsView0->fitInView(item[0], Qt::KeepAspectRatio);

item[0]->setPixmap(image.at(img)->getPixmap(0));
scene[0]->setSceneRect(0, 0, item[0]->pixmap().width(), item[0]->pixmap().height());
ui->graphicsView0->fitInView(item[0], Qt::KeepAspectRatio);

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