code: def _center_transform(self, transform):
          ''''
          Works like setupTransform of a version of java nodebox
          http://dev.nodebox.net/browser/nodebox-java/branches/rewrite/src/java/net/nodebox/graphics/Grob.java
          '''
          dx, dy = self._get_center()
          t = cairo.Matrix()
          t.translate(dx, dy)
          t = transform * t
          t.translate(-dx, -dy)
          return f _center_transform(self, transform):
          ''''
          Works like setupTransform of a version of java nodebox
          http://dev.nodebox.net/browser/nodebox-java/branches/rewrite/src/java/net/nodebox/graphics/Grob.java
          '''
          dx, dy = self._get_center()
          t = cairo.Matrix()
          t.translate(dx, dy)
          t = transform * t
          t.translate(-dx, -dy)
          return t
docs: Works like setupTransform of a version of java nodebox
          http://dev.nodebox.net/browser/nodebox-java/branches/rewrite/src/java/net/nodebox/graphics/Grob.java