[PyQt] Create a start Button

[Fabien Lafont]

Hello everyone,

I'm trying to create a Start button on my soft. My software just plot
live datas. When I run the program it display only a pristine graph
and I want to start the first action of my program when I click on
start. But If I create this Start button nothing appears...

Why just creating this button block the display of my soft?


# -*- coding: utf-8 -*-
"""
Created on Mon Dec 19 14:51:39 2011

@author: lafont
"""
#!/usr/bin/env python

from visa import *
from pylab import *
import sys
from PyQt4 import QtGui
import numpy as np
import random
import ImageGrab
from PyQt4 import QtCore, QtGui
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QTAgg
as NavigationToolbar
from PyQt4.QtGui import (QApplication, QLabel, QLineEdit, QSpinBox,
        QVBoxLayout, QDial, QGridLayout, QComboBox, QPushButton)
from PyQt4.QtCore import (QObject, Qt, SIGNAL, SLOT)


#===============================================================================
#
#===============================================================================


class CPUMonitor(FigureCanvas):
    def __init__(self,parent):

        self.fig = Figure()
        self.ax = self.fig.add_subplot(111)
        FigureCanvas.__init__(self, self.fig)
        self.ax.set_autoscale_on(True)
        # generates first "empty" plots
        self.user, self.nice = [], []
        self.l_user, = self.ax.plot([], self.user, label='Voltage')
        self.l_nice, = self.ax.plot([], self.nice, label='Voltage2')

        # force a redraw of the Figure
        self.fig.canvas.draw()
#        FigureCanvas.updateGeometry(self)


    def action1(self):

        self.result1 = random.randint(0,4)
        QtCore.QTimer.singleShot(100, self.action2)


    def action2(self):
        self.result2 = random.randint(0,1)

        self.user.append(self.result1)
        self.nice.append(self.result2)

        self.l_user.set_data(range(len(self.user)), self.user)
        self.l_nice.set_data(range(len(self.nice)), self.nice)

        # force a redraw of the Figure
        self.fig.canvas.draw()
        FigureCanvas.updateGeometry(self)

        #envoie de l'évènement ici

        self.action1()
#

#===============================================================================
#
#===============================================================================



class ApplicationWindow(QtGui.QMainWindow):
    """Example main window"""
    def __init__(self):
        # initialization of Qt MainWindow widget
        QtGui.QMainWindow.__init__(self)
        # set window title
        self.setWindowTitle("QHE manip")
        # instantiate a widget, it will be the main one
        self.main_widget = QtGui.QWidget(self)
        # create a vertical box layout widget
        vbl = QtGui.QGridLayout(self.main_widget)


        StartButton = QPushButton("START")
        self.connect(StartButton, SIGNAL('released()'),
CPUMonitor.action1)


        # instantiate our Matplotlib canvas widget
        qmc = CPUMonitor(self.main_widget)

        # instantiate the navigation toolbar
        ntb = NavigationToolbar(qmc, self.main_widget)

        # pack these widget into the vertical box

        vbl.addWidget(qmc,0,0)
        vbl.addWidget(ntb,1,0)
        vbl.addWidget(StartButton,4,0)


        # set the focus on the main widget
        self.main_widget.setFocus()
        # set the central widget of MainWindow to main_widget
        self.setCentralWidget(self.main_widget)

#    def arret(self):
#        stop = False
#        print stop
#    def commence(self):
#        stop = True
# create the GUI application
qApp = QtGui.QApplication(sys.argv)
# instantiate the ApplicationWindow widget
aw = ApplicationWindow()
# show the widget
aw.show()
# start the Qt main loop execution, exiting from this script
# with the same return code of Qt application
sys.exit(qApp.exec_())