Trying to print from pyqt

pyqt_print.py

import sys
import numpy as np
from PyQt4.QtCore import *
from PyQt4.QtGui import *
#from xlwt import *
from pylab import plot, show

from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar2


class ViewWidget(QMainWindow):
     def __init__(self):
         QMainWindow.__init__(self)

         # create a simple main widget to keep the figure
         self.mainWidget = QWidget()
         self.setCentralWidget(self.mainWidget)

         layout = QVBoxLayout()
         self.mainWidget.setLayout(layout)

         # create a figure
         self.figure_canvas = FigureCanvas(Figure())
         layout.addWidget(self.figure_canvas, 10)

         # and the axes for the figure
         self.axes = self.figure_canvas.figure.add_subplot(111)
         x = np.linspace(0.,2*np.pi,100)
         self.axes.plot(x,np.sin(x),label='sin(x) ')
         self.axes.plot(x,np.cos(x),label='cos(x) ')
         self.axes.figure.set_facecolor('white') 
         self.axes.grid('on')
         self.axes.legend()
         # add a navigation toolbar
         self.navigation_toolbar = NavigationToolbar2(self.figure_canvas, self)
         layout.addWidget(self.navigation_toolbar, 0)

         self.print_button = QPushButton()
         self.print_button.setIcon(QIcon("Fileprint.png"))
         self.print_button.setToolTip("Print the figure")
         self.navigation_toolbar.addWidget(self.print_button)
         self.connect(self.print_button, SIGNAL('clicked()'), self.goPrinter)

         self.quit_button = QPushButton("&Quit")
         self.navigation_toolbar.addWidget(self.quit_button)
         self.connect(self.quit_button, SIGNAL('clicked()'), self.close)
         
     def goPrinter(self):
         printer = QPrinter()
         printer.A4
         printer.HighResolution
         printer.Color
         anotherWidget= QPrintDialog(printer,self)
         if(anotherWidget.exec_() != QDialog.Accepted):
             return
         p = QPixmap.grabWidget(self.figure_canvas)
         printLabel = QLabel()
         printLabel.setPixmap(p)
         painter = QPainter(printer)
         printLabel.render(painter)
         painter.end()

         show()

if __name__=="__main__":
     app=QApplication(sys.argv)
     mw=ViewWidget()
     mw.show()
     sys.exit(app.exec_())