PyQt4 Picture Viewer

import sys
from PyQt4 import QtGui

class PictureViewer( QtGui.QMainWindow ):
    def __init__( self ):
        super( PictureViewer, self ).__init__()

        self.initUI()

    def initUI( self ):
        openAction = QtGui.QAction( '&Open', self )
        openAction.setShortcut( 'Ctrl+O' )
        openAction.triggered.connect( self.onOpen )

        menubar = self.menuBar()
        fileMenu = menubar.addMenu( '&File' )
        fileMenu.addAction( openAction )

        main = QtGui.QWidget( self )

        self.pic = QtGui.QLabel()

        scrollArea = QtGui.QScrollArea()
        scrollArea.setWidgetResizable( True )
        scrollArea.setWidget( self.pic )

        hbox = QtGui.QHBoxLayout()

        hbox.addWidget( scrollArea )

        main.setLayout( hbox )

        self.setCentralWidget( main )

        self.resize( 640, 480 )
        self.center()

        self.setWindowTitle( 'Picture Viewer' )
        self.show()

    def center( self ):
        qr = self.frameGeometry()
        cp = QtGui.QDesktopWidget().availableGeometry().center()
        qr.moveCenter( cp )
        self.move( qr.topLeft() )

    def onOpen( self ):
        fname = QtGui.QFileDialog.getOpenFileName( self, 'Open image', '', 'Images (*.png *.jpg *.bmp)' )

        if( fname != None and fname != "" ):
            pixmap = QtGui.QPixmap( fname )
            self.pic.setPixmap( pixmap )

def main():
    app = QtGui.QApplication( sys.argv )
    pv = PictureViewer()
    sys.exit( app.exec_() )

if __name__ == '__main__':
    main()