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Thread: Problem applying QGraphicsBlurEffect to a QGraphicsPixmapItem

  1. #1
    ucomesdag Guest

    Default Problem applying QGraphicsBlurEffect to a QGraphicsPixmapItem

    Hi all,

    I try to apply blur to an image but nothing seems to happen and can't wrap my head arround whatmight be wrong here:

    Qt Code:
    1. QPixmap buffer(image.size());
    2. QGraphicsPixmapItem item(buffer);
    3. QGraphicsBlurEffect effect;
    4. effect.setBlurHints(QGraphicsBlurEffect::QualityHint);
    5. effect.setBlurRadius(5);
    6. item.setGraphicsEffect(&effect);
    7.  
    8. item.pixmap().toImage().save("blur.png");
    To copy to clipboard, switch view to plain text mode 

  2. #2
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    Default Re: Problem applying QGraphicsBlurEffect to a QGraphicsPixmapItem

    Ehm, you are constructing an empty pixmap, and blur an empty pixmap results in an empty pixmap You might want to try
    Qt Code:
    1. QPixmap buffer(image);
    To copy to clipboard, switch view to plain text mode 

    And also I think that the pixmap function of the item returns the unmodified source pixmap of the item. But I am not sure on that. So if you want save it you have to render the scene or set the pixmap to a label and render that back to a pixmap.

  3. #3
    ucomesdag Guest

    Default Re: Problem applying QGraphicsBlurEffect to a QGraphicsPixmapItem

    Nope it ain't an empty pixmap. But you hit a point, how could I render it as it's offscreen?

  4. #4
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    Default Re: Problem applying QGraphicsBlurEffect to a QGraphicsPixmapItem

    You will probably have to add your item to a QGraphicsScene, which you can then render() off-screen using your own QPainter. See also QGraphicsView::render() for off-screen rendering and some examples related to printing.

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