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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">I’m having an issue with QGraphicsItem::itemChange.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Here is the test program :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal">import PyQt5.Qt as qt <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">class Node( qt.QGraphicsRectItem ) : <o:p>
</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> def __init__( self , sector ) : <o:p>
</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> super( Node , self ).__init__( sector )<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> def itemChange( self , change , v ) :
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> res = super( Node , self ).itemChange( change , v )<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> print "itemChange return value : ",res<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> return res<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">b = qt.QGraphicsLineItem()<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">c = qt.QGraphicsLineItem()<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">a = Node(b)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">print a.parentItem(),b<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">a.setParentItem(c)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">print a.parentItem(), c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I get this output :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><PyQt5.QtWidgets.QGraphicsLineItem object at 0x8f9f194> <PyQt5.QtWidgets.QGraphicsLineItem object at 0x8f9f194><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">itemChange return value : <PyQt5.QtWidgets.QGraphicsLineItem object at 0x8f9f1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">itemChange return value : <PyQt5.QtWidgets.QGraphicsLineItem object at 0x8f9f1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">None <PyQt5.QtWidgets.QGraphicsLineItem object at 0x8f9f1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">If I remove itemChange, I get this output :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><PyQt5.QtWidgets.QGraphicsLineItem object at 0xf2e6814c> <PyQt5.QtWidgets.QGraphicsLineItem object at 0xf2e6814c><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><PyQt5.QtWidgets.QGraphicsLineItem object at 0xf2e68194> <PyQt5.QtWidgets.QGraphicsLineItem object at 0xf2e68194><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m using PyQt-5.0, Sip 4.14.7 and Qt 5.1.0<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I tried with PyQt-5.0.1, sip 4.15.1 and Qt 5.1.0 without change.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I digged into this, basically when setParentItem is called itemChange is called on this item and use the return value of itemChange to set the parent.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">In C itemChange returns a QVariant, which must be casted as a QGraphicsItem to be set as a parent.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">This took me to the Chimera::parse_py_type function. Apparently, someone (QT?) registers QGraphicsItem as a QMetaType, but not QGraphicsLineItem.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">If I replace :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">_metatype = QMetaType::type(_name.constData());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">By :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">if(strcmp(_name.constData(),"QGraphicsLineItem*")==0)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> _metatype = QMetaType::type("QGraphicsItem*");<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">else <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> _metatype = QMetaType::type(_name.constData());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">(I know how bad this is, but it’s for demonstration purpose.)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">The output of the test program is then :<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba194> <PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba194><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">itemChange return value : <PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">itemChange return value : <PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba1dc> <PyQt5.QtWidgets.QGraphicsLineItem object at 0x89ba1dc><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Any ideas on how to fix this properly ?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Yann.<o:p></o:p></span></p>
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