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Thread: QGraphicsView - resize items on graphicsview resize -> calculate new positions

  1. #1
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    Default QGraphicsView - resize items on graphicsview resize -> calculate new positions

    Hey Guys,

    I am using a GraphicsView with a GraphicsScene which i added a PixmapItem....
    The QGraphicsPixmapItem is treated as my background item on Z-value "0" on Z-value "1" i have several other pixmapItems.

    My Problem:
    When i resize the whole program the QGraphicsView also resizes and so the Background item should be resized (what works fine) - it is just a *.scaled() Pixmap where scaled() gets the current size of the GraphicsView.
    Now i have to reposition the items on Z-value "1" to match the "same" position as before on the underlaying pixmap

    My current Solution:
    My current solution is not correct becauze the repositioning does "not work" - it's not exact .. (for the Background PixmapItem i used Qt::KeepAspectRatio)
    I saved the original size of the background Pixmap and the position of each Item for that "base size"
    On resizing i calculate the new x and y coordinates by referring to the old width/height of the Background Pixmap

    This means:
    NewWidth/oldWidth * oldX-Coordinate = NewX-Coordinate
    NewHeight/oldHeight * oldY-Coordinate = NewY-Coordinate

    Anyway .. it's "kinda" working but not exact (i thought it would work better that way ^^)

    Anybody an idea how it is possible to calculate that more precisely?? - Would be really lovely
    Thanks =)

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  3. #2
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    Default Re: QGraphicsView - resize items on graphicsview resize -> calculate new positions

    Has nobody any idea? There must be a smart way to solve this i think!?

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  5. #3
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    Default Re: QGraphicsView - resize items on graphicsview resize -> calculate new positions

    I'm just wondering, why you have to change position of the items in the scene?

    Wouldn't it be simpler to add all the items to the scene in the places you want them, and then on every resize call QGraphicsView::fitInView() ?

    This will make sure that everything is scalled as required and positioned correctly (that's assuming that you're not bothered that everything will get smaller/bigger as you change window size).

    Unless I've misunderstood what you want to achieve.

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    shock (11th December 2011)

  7. #4
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    Default Re: QGraphicsView - resize items on graphicsview resize -> calculate new positions

    Hmm ... seems it was really that simple... Thanks man

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