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Thread: best way to detect when user stops moving a QGgraphicsItem

  1. #1
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    Default best way to detect when user stops moving a QGgraphicsItem

    I'm messing around with simple selectable + movable tiles in a graphics view/scene. When the user releases the LMB after dragging a Qgraphicsitem I want to invoke some actions.

    Do I have to sub-class the scene/item and watch mouse events to identify this?
    Last edited by amleto; 15th June 2013 at 14:41.
    If you have a problem, CUT and PASTE your code. Do not retype or simplify it. Give a COMPLETE and COMPILABLE example of your problem. Otherwise we are all guessing the problem from a fabrication where relevant details are often missing.

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    Default Re: best way to detect when user stops moving a QGgraphicsItem

    I am hard pressed to figure out how to retrieve the identity of a QGraphicsItem from a QGraphicsScene::dropEvent() if you install an event filter on the scene (or view). It looks like the best you can do is retrieve the coordinates from the event, then query the scene for the item at that location. It seems stupid if Qt makes you subclass all QGraphicsItem types just to handle drag / drop.

    Have you looked at the code for the elasticnodes example? Does that use drag / drop to move the nodes?

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    Default Re: best way to detect when user stops moving a QGgraphicsItem

    I looked at that example - the moving of the nodes is just done with 'normal' graphics view implementation and there is no 'drop' notification anywhere.

    the example uses a Scene method ( QGraphicsItem *mouseGrabberItem() const; ) to identify when a node is being held by a user.
    If you have a problem, CUT and PASTE your code. Do not retype or simplify it. Give a COMPLETE and COMPILABLE example of your problem. Otherwise we are all guessing the problem from a fabrication where relevant details are often missing.

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