title: PyQt5 triggering a paintEvent() with keyPressEvent()
body: <p>I am trying to learn PyQt vector painting. Currently I am stuck in trying to pass information to paintEvent() method which I guess, should call other methods:</p>
  
  <p>I am trying to paint different numbers to a fundamental block (here drawFundBlock() method, which should draw some lines). The code is trying to check if right arrow is pressed-> drawFundamental block and if number is pressed (now trying to simply draw "5"), it will draw that number on a certain area on that fundamental block. But I can't seem to get the QPainter to work. It seems it's calling the paintEvent() override method twice now (why?). Some people have suggested the update() method, but I have no idea how to still pass any arguments to paintEvent(), which should determine whether to draw "fundblock" or "number". Now the code uses update() for demonstration but this simply moves the lines - But the already Added Lines should remain!</p>
  
  <p>Any help?</p>
  
  <pre><code># Test QPainter etc.
  
  from PyQt5.QtWidgets import QWidget, QApplication
  from PyQt5.QtGui import QPainter, QPen, QColor, QFont
  from PyQt5.QtCore import Qt, QPoint, pyqtSignal, QRect
  import sys
  
  class Example(QWidget):
  
      paintTrigger = pyqtSignal()
  
      def __init__(self):
          super().__init__()
          self.initUI()
          self.ydist = 15
          self.eveType = "drawBlock"
          self.currentRegion = QRect(50,50,50,80)
          #self.paintTrigger[self.eveType].connect(lambda:self.paintEvent())
  
          self.x0=5
          self.x1=25
          self.y0=5
          self.y1=25
  
      def initUI(self):
          self.setGeometry(300,300,280,270)
          self.setWindowTitle('Painter training')
          self.show()
  
      # How to pass info here, which type of drawing should be done (block or number)?
      def paintEvent(self,event):
          qp = QPainter(self)
          qp.begin(self)  
          self.drawFundBlock(qp)
          qp.end()
  
      def drawFundBlock(self,qp):
          pen = QPen(Qt.black, 2, Qt.SolidLine)
          pen.setStyle(Qt.DashLine)
  
          qp.setPen(pen)
          for i in range(1,10):
              #qp.drawLine(0,i*self.ydist,40,i*self.ydist)
              qp.drawLine(self.x0,i*self.y0,self.x1,self.y0*i)
  
          #notePoint=QPoint(200,200)
          #qp.drawText(notePoint,"5")
  
      def drawNumber(self,qp,notePoint):
          pen = QPen(Qt.black,2,Qt.SolidLine)
          #qp.setPen(QColor(200,200,200))
          qp.setPen(pen)
          qp.setFont(QFont('Arial', 10))
          qp.drawText(notePoint,"5")
  
      def nextRegion(self):
          self.x0=self.x0+30
          self.x1=self.x1+30
          self.y0=self.y0+30
          self.y1=self.y1+30
  
      def keyPressEvent(self,event):
          # Did the user press a button??
          gey=event.key()
          if gey == Qt.Key_M: 
              print("Key 'm' pressed!")
          elif gey == Qt.Key_Right:
              print("Right key pressed!, call drawFundBlock()")
              #self.paintTrigger["drawBlock"].emit()
              #self.paintEvent()
              self.update()
              self.nextRegion()
  
          elif gey == Qt.Key_5:
              print("#5 pressed, call drawNumber()")
              #self.paintTrigger["drawNo"].emit()
  
  
  if __name__ == '__main__':
      app = QApplication(sys.argv)
      ex = Example()
      sys.exit(app.exec_())
  </code></pre>