Can't move QGraphicsEllipseItem

cpper

Hi, I'm trying to draw a circle, and the move it 150 pixels on the X axis. Here is the simplified code:

QGraphicsScene scene;
QGraphicsEllipseItem circle;

scene.addItem(&circle);
circle.setRect(150,-0,200,200);    
circle.setPos(150,0);
circle.moveBy(150,0);
circle.setX(150);

The value 150 in the four lines do nothing. What's the correct way to move the item ?

sierdzio

circle.moveBy(150,0);

This moves your circle so x == 300.

circle.setX(150);

This moves it back to x == 150.

So it all works correctly (unless I misunderstood you).

cpper

@sierdzio The last four lines are my attempts to move the circle, but none work. The circle is still in the center of the scene.

sierdzio

All look correct. Can you show relevant parts of your real code? Perhaps there is something wrong there.

cpper

@sierdzio I just found out the problem. I was only experimenting with a single circle, and it seems that after the translation, the whole scene is moved so that its contents are centered.
When adding a second circle at 0,0 I now can notice the first one is indeed translated. The center of the scene is now the point between the circles.
Is there a way to fix the scene, so that it stops centering its contents ?

Pl45m4

@cpper

Set a static sceneRect to your QGraphicsScene.

graphicsView->scene()->setSceneRect(0, 0, graphicsView->width(), graphicsView->height());

cpper

@Pl45m4 said in Can't move QGraphicsEllipseItem:

graphicsView->scene()->setSceneRect(0, 0, graphicsView->width(), graphicsView->height());

Thanks guys. That works fine.