I want do draw polylines with many control points in a PyQt4 / PySide application. The point coordinates come from a NumPy array and must be put into a `QPolygonF`

in order to be drawn with `QPainter.drawPolyline(...)`

.

With PyQt4, this can be done efficiently e.g. with something like this:

```
import numpy as np
from PyQt4.QtGui import *
n = 3
qpoints = QPolygonF(n)
vptr = qpoints.data()
vptr.setsize(8*2*n)
aa = np.ndarray( shape=(n,2), dtype=np.float64, buffer=buffer(vptr))
aa.setflags(write=True)
aa[:,0] = np.arange(n)
aa[:,1] = np.arange(n)
for i in range(n):
print qpoints.at(i)
```

This works, because, when using PyQt4, `QPolygonF.data()`

returns something (a `sip.voidptr`

object) which speaks the Python buffer protocol.

The problem now is that if I try to run the above code using PySide instead of PyQt4, `QPolygonF.data()`

just returns a `QPointF`

object (with the coordinates of the first point in the `QPolygonF`

) and is thus useless.

So my question is: is there any known workaround to this? How can I, with PySide, put data into a `QPolygonF`

without inserting `QPointF`

objects, element-wise?

This should work

```
from pylab import *
from PySide.QtGui import QPolygonF
from PySide.QtCore import QPointF
xy = resize(arange(10),(2,10)).T
qPlg = QPolygonF()
for p in xy:
qPlg.append(QPointF(*p))
```

Hope it helps!

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