The DiveTextItems were redrawn on every paint() call. This was
a prohibitively expensive operation (converting the text into
a path, drawing an outline, etc.), which was called numerous
times.
Instead, render the text only when changing into a QPixmap
and blit that pixmap in the paint() call.
This will make it possible to do absolutely positioned
DiveTextItems. So far they were placed relatively in
scene coordinates ranging from 0-100(!).
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
15f20961c7