drawing lines using qpainter from file

[neutrino]

I'm new to Qt programming and trying to build a gui program for a project. I need to draw multiple lines on the widget. The dimensions of the lines are stored in a file "line.txt". The file is correctly read by using qfile and qtextstream. I have also implemented the paintEvent() to draw one line. But when i'm trying to draw multiple lines, it shows no output. What's the problem and how to correct it? i'm attaching the code and the file "line.txt"