title: Changing Pixmap image automatically at runtime in PyQt
body: <p>I wish to change the image of a pixmap being displayed in a window automatically using a while loop that has a defined delay and uses locations of images stored in a string list.
   All possibilities I tried led to the first image being displayed but not changing at runtime.
  Any changes gets reflected only after the program has completed all kinds of execution.</p>
  
  <pre><code>from PyQt4 import QtCore, QtGui
  import time
  import sys
  
  try:
      _fromUtf8 = QtCore.QString.fromUtf8
  except AttributeError:
      def _fromUtf8(s):
          return s
  
  try:
      _encoding = QtGui.QApplication.UnicodeUTF8
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig, _encoding)
  except AttributeError:
      def _translate(context, text, disambig):
          return QtGui.QApplication.translate(context, text, disambig)
  
  
  class Ui_Form(QtGui.QWidget):
      def __init__(self):
          QtGui.QWidget.__init__(self)
          self.setupUi(self)
      def setupUi(self, Form):
          Form.setObjectName(_fromUtf8("Form"))
          Form.resize(598, 555)
          self.horizontalLayout = QtGui.QHBoxLayout(Form)
          self.horizontalLayout.setObjectName(_fromUtf8("horizontalLayout"))
          self.start_pulse = QtGui.QPushButton(Form)
          self.start_pulse.setObjectName(_fromUtf8("start_pulse"))
          self.horizontalLayout.addWidget(self.start_pulse)
          self.label = QtGui.QLabel(Form)
          self.label.setAutoFillBackground(True)
          self.label.setText(_fromUtf8(""))
          self.label.setPixmap(QtGui.QPixmap(_fromUtf8("GUI.png")))
          self.label.setScaledContents(True)
          self.label.setObjectName(_fromUtf8("label"))
          self.horizontalLayout.addWidget(self.label)
  
          self.retranslateUi(Form)
          QtCore.QMetaObject.connectSlotsByName(Form)
  
  
      def retranslateUi(self, Form):
          Form.setWindowTitle(_translate("Form", "Form", None))
          self.start_pulse.setText(_translate("Form", "start", None))
          self.start_pulse.clicked.connect(self.soumyajit)
      def soumyajit(self):
          j=0
          while(1):
              print("change")
              if j==0:
                  self.label.setPixmap(QtGui.QPixmap(_fromUtf8("GUI2.png")))
              if j==1:
                  self.label.setPixmap(QtGui.QPixmap(_fromUtf8("GUI.png")))
              if j==2:
                  self.label.setPixmap(QtGui.QPixmap(_fromUtf8("GUI2.png")))
              if j==3:
                  self.label.setPixmap(QtGui.QPixmap(_fromUtf8("GUI.png")))
              j=j+1
              #delay
              time.sleep(.5)
  if __name__=='__main__':
          app=QtGui.QApplication(sys.argv)
          ex = Ui_Form()
          ex.show()
          sys.exit(app.exec_())
  </code></pre>