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<TITLE>Re: [PyQt] QGraphicsPolygonItem / porting from QCanvas to QGraphicsScene</TITLE>
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<FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>The constructor expects a QGraphicsItem, you are giving it a canvas.<BR>
<BR>
Note that the symantics of Qcanvas and QGraphicsScene are different. <BR>
<BR>
Here is a stupid example:<BR>
<BR>
class HideButton(QtGui.QGraphicsPolygonItem):<BR>
fgcolor = QtGui.QColor(20,20,20, 180)<BR>
bgcolor = QtGui.QColor(180,180,180)<BR>
<BR>
def __init__(self, parent):<BR>
p = QtCore.QPointF<BR>
points = QtGui.QPolygonF()<BR>
// these points are relative to the parent<BR>
for poly in (p(-6,-6),p(6,-6),p(0,6)):<BR>
points.append(poly)<BR>
<BR>
QtGui.QGraphicsPolygonItem.__init__(self, points, parent)<BR>
self.setBrush( QtGui.QBrush( self.bgcolor ) )<BR>
self.setPen( QtGui.QPen(self.fgcolor,2) )<BR>
<BR>
Now we can add a hide button as a child of another graphics item...<BR>
<BR>
self.button = HideButton(item)<BR>
<BR>
And this will take care of rendering with the parent is visible.<BR>
<BR>
To add the top level item to the scene:<BR>
<BR>
scene.addItem( item )<BR>
<BR>
And then make sure to add this scene to your view.<BR>
<BR>
I hope that this helps.<BR>
On 1/21/09 8:38 AM, "Michael Krauss" <<a href="hippodriver@gmx.net">hippodriver@gmx.net</a>> wrote:<BR>
<BR>
</SPAN></FONT><BLOCKQUOTE><FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Hello list members,<BR>
<BR>
i am porting a program from PyQt3 to PyQt4. It formerly used QCanvas<BR>
and QCanvasView. Now i am using QGraphicsScene and QGraphicsView.<BR>
<BR>
I replaced QCanvasPolygonalItem with QGraphicsPolygonItem but its<BR>
constructor doesn't work as expected.<BR>
<BR>
The old code:<BR>
<BR>
class GuiVertex(QCanvasPolygonalItem):<BR>
'''<BR>
Graphical representation of a vertex<BR>
'''<BR>
def __init__(self, text, canvas):<BR>
QCanvasPolygonalItem.__init__(self, canvas)<BR>
[...]<BR>
<BR>
The new code:<BR>
<BR>
class GuiVertex(QGraphicsPolygonItem):<BR>
'''<BR>
Graphical representation of a vertex<BR>
'''<BR>
def __init__(self, text, canvas):<BR>
QGraphicsPolygonItem.__init__(self, canvas)<BR>
[...]<BR>
<BR>
The error message:<BR>
<BR>
[mickraus@gandalf src]\$ python gui.py<BR>
Traceback (most recent call last):<BR>
File "gui.py", line 420, in <module><BR>
main()<BR>
File "gui.py", line 414, in main<BR>
gui = Gui()<BR>
File "gui.py", line 343, in __init__<BR>
self.board.addVertex(str(v), x, y)<BR>
File "gui.py", line 221, in addVertex<BR>
vertex = GuiVertex(text, self)<BR>
File "gui.py", line 157, in __init__<BR>
QGraphicsPolygonItem.__init__(self, canvas)<BR>
TypeError: argument 1 of QGraphicsPolygonItem() has an invalid type<BR>
<BR>
According to the manual<BR>
<a href="http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qgraphicspolygonitem.html">http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qgraphicspolygonitem.html</a><BR>
the constructor expects a QGraphicsItem. As GuiVertex is a (sub)^4class<BR>
of QGraphicsItem I don't understand the TypeError. The second argument<BR>
passed to QGraphicsPolygonItem.__init__ in line 221 is of type<BR>
"class Board(QGraphicsScene)".<BR>
<BR>
<BR>
Kind regards,<BR>
Michael Krauss<BR>
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<BR>
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