[FIXED] Python & Qt, QGraphicsScene Collision and typeid (from c++)

Issue

I'm having big trouble finding help on this subject.

I managed to have a collision detection working but now I want to detect the type of the colliding object. It's a QGraphicsPixmapItem for now.

I've already coded that in c++ but now that python don't know about typeid I don't know what to do.

Python func:

def IsColliding(self, charView):
        collision_list = self.Map_Scene.collidingItems(charView, mode=QtCore.Qt.IntersectsItemShape)
        if collision_list:
            print(collision_list)
            print(typeid(collision_list[0])) ## Error here
            return True
        else:
            return False

Working c++ equivalent code:

void xGame::placeBlock(int xpos, int ypos, QString blockName, bool isObs) {
    //place new block
    block = new xBlock(blockName, isObs);
    block->setPos(xpos, ypos);
    block->setZValue(1);
    scene->addItem(block);

    //remove old block
    QList<QGraphicsItem *> colliding_items = block->collidingItems();
    for (int i = 0, n = colliding_items.size(); i < n; ++i) {
        if (typeid(*(colliding_items[i])) == typeid(xBlock)) {
            scene->removeItem(colliding_items[i]);
            delete colliding_items[i];
        }
    }
}

Solution

The base class QGraphicsItem has a "type" method that returns an "int" and is exactly for this purpose. It should be a lot more efficient than using typeid or anything that involves string lookups or comparisons. Each of the built-in classes derived QGraphicsItem have a unique type, and when you derive your own classes, just implement the "type" method in your class and return a unique value.

Look in the docs for QGraphicsItem::UserType. There's an example there. Qt reserves values up to 65535 for itself, and user types start at 65536.

Answered By - goug