Question

QPolygonF has methods to union, intersect, and subtract with other QPolygonFs but I need to perform an intersection test with a QLineF. This appears to be missing from the API.

I suppose I could do something like this:

if (polygon .containsPoint (line .p1 ()) != polygon .containsPoint (line .p2 ())
    return true;

QPointF a = polygon .back ();
foreach (QPointF b, polygon)
{
    if (QLineF :: BoundedIntersection == line .intersect (QPointF (a, b))
       return true;
    a = b;
}

return false;

There are probably some numerical or edge-case surprises lurking in the above, so I’d rather not.

Is there a provided method somewhere in the Qt API that I can’t see?

Answer 1

Unfortunately, the answer is “no”.