<![CDATA[QGraphicscene changes size]]>Hello all,

I encountered a problem with QGraphicsscene. I am making a simple pong game and using a graphicsscene where I put my items in. But when I want to reset the game and put all the items back in their original position the graphicsscine seems like it had gotten twice(or more) bigger. Is there a way to keep the scene always at the same size, I couldn't find anything about this on the internet.
Thanks!

]]>https://forum.qt.io/topic/89131/qgraphicscene-changes-sizeRSS for NodeTue, 14 Apr 2026 15:26:14 GMTFri, 23 Mar 2018 13:33:09 GMT60<![CDATA[Reply to QGraphicscene changes size on Mon, 26 Mar 2018 14:52:32 GMT]]>@mrjj
Thanks for the answer. This worked! Thank you!

]]>https://forum.qt.io/post/449654https://forum.qt.io/post/449654Mon, 26 Mar 2018 14:52:32 GMT<![CDATA[Reply to QGraphicscene changes size on Mon, 26 Mar 2018 10:37:40 GMT]]>@Vera
Hi
there are function to map from items coordinates to global and reverse
QPointF QGraphicsItem::mapToScene(const QPointF &point)
That should report 400x300 for that item.

Did you read
http://doc.qt.io/qt-5/graphicsview.html
The Graphics View Coordinate System ?

]]>https://forum.qt.io/post/449613https://forum.qt.io/post/449613Mon, 26 Mar 2018 10:37:40 GMT<![CDATA[Reply to QGraphicscene changes size on Mon, 26 Mar 2018 10:30:09 GMT]]>Thanks for your reply.
And sorry for the late response.
I set them both but that didn't seem to help, but I found out after a long search that the objects i put inside the scene get their own coordinate system. When I put an object in at 400, 300 it is there but when it has moved and I want it back at its original place I have to set it position to 0,0 to reset it. This is really annoying as I cant use the dimension of the scene to check if the ball in the game has a collision with the top wall.
Is there a way to have the objects always use the coordinate system from the scene?

]]>https://forum.qt.io/post/449610https://forum.qt.io/post/449610Mon, 26 Mar 2018 10:30:09 GMT<![CDATA[Reply to QGraphicscene changes size on Fri, 23 Mar 2018 14:14:05 GMT]]>@Vera
QGraphicsView::setScreneRect()
QGraphicsScene::setSceneRect()

If one those are not set the default value is the bounding rect of all child items.

]]>https://forum.qt.io/post/449222https://forum.qt.io/post/449222Fri, 23 Mar 2018 14:14:05 GMT