Insert painter->rotate(45);
before painter->drawText(75, 100 + i * 800/9 - 6, 40, 40, 1, str);
and painter->rotate(-45);
after (to restore the rotation angle of the coordinate system):
painter->rotate(45);
painter->drawText(75, 100 + i * 800/9 - 6, 40, 40, 1, str);
painter->rotate(-45);
Depending on if you mean 45 degrees clockwise or anti-clockwise you may need to negate the rotation angles.
After you rotate the coordinate system, everything you paint will be painted rotated until you restore the painter. A convenient way of saving and restoring the state of the painter is using QPainter::save()
and QPainter::restore()
.