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POQt Adding children to a QGraphicsItem derivate in a QGraphicsScene do not show up
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2012-03-08T19:30:24.927
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2012-03-08T19:41:00.833
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I subclassed QGraphicsItem twice: RingCollection is a kind of container item that should be filled with a list of child items of type RingCollectionItem. To achieve this, there is a populate() method, that (for testing) simply generates one item and sets its parent to the current collection. Now, when I add the item to the collection inside the populate method, it does not show up in the scene. When I add it directly , it's there. I'm quite puzzled (and frankly, reaching this minimal test case took me ages, cause I had no idea where to look for the problem...) So here it goes: Code in main (extract): <pre><code>// works, both collection and item are drawn RingCollection collection(QPoint(0,0),150); RingCollectionItem newitem; newitem.setParentItem(&collection); newitem.setPos(10.0, 10.0); scene.addItem(&collection); </code></pre> The other method: <pre><code>//does not work: only the collection is drawn RingCollection collection(QPoint(0,0),150); collection.populate(); scene.addItem(&collection); </code></pre> and the void populate() method: <pre><code>RingCollectionItem newitem; newitem.setParentItem(this); newitem.setPos(10.0, 10.0); </code></pre> Maybe anyone can see what I'm missing, as far as I can tell both does basically the same thing. My best guess is that passing this somehow doesn't do what I expect it to, although I've seen examples do this... (In my understanding, this is a pointer to the current instance, please correct me if I got this wrong). Cheers, Louise PS: I tested that populate actually gets called, just in case. It does ;)
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Qt Adding children to a QGraphicsItem derivate in a QGraphicsScene do not show up
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