I am trying to create indentation guides for basic text viewer. Currently I have stopped at following piece of code:

Qt Code: 
  1. def paintEvent(self, event):
  2.             font = QtGui.QFont('Courier', 10, QtGui.QFont.Light)
  3.             font_metrics = QtGui.QFontMetrics(font)
  4.             self.font_width = font_metrics.width('X')
  5.             self.font_height = font_metrics.height()
  6.             self.setFont(font)
  7.  
  8.             painter = QPainter(self.viewport())
  9.             #painter.begin()
  10.             longest_line = 20
  11.             from_top = 0
  12.             painter.setPen(QtGui.QColor(0, 100, 200, 200))
  13.             for i in range(0, longest_line):
  14.                 the_x = self.font_width + (i * 4 * self.font_width)
  15.                 painter.drawLine(the_x, from_top, the_x, from_top + self.font_height)
  16.  
  17.             QPlainTextEdit.paintEvent(self, event)
  18.             #painter.end()
  19.             #self.updateScrollbars()
  20.             super(QPlainTextEdit, self).paintEvent(event)
  21.             return
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This code is not finished as it seems to me somewhat ugly solution. My question is -- is there any guide, or piece of code I can learn from? It does not matter which language. I also could not find relevant topics in this forum, search results are too verbose.

And just to clarify, this is what I am trying to reproduce: https://visualstudiogallery.msdn.mic...5-630980e72c30.