Draw A line on image using Qt

A quick search for "qt rubber band line" yields these results:
http://www.qtcentre.org/threads/3596-Draw-rubberband-line

http://lists.trolltech.com/qt-interest/2001-12/thread00642-0.html

See also:
http://doc.qt.nokia.com/4.7-snapshot/painting-basicdrawing.html

In the above, they have drawn a rectangle, you need to modify this to draw a line. Also make sure that you're painting the bitmap before drawing the line, so this gives the appearance that the line is drawn on the image. A similar method for drawing text.

To achieve a flicker-free performance, you need to do double-buffering:
http://doc.qt.nokia.com/qq/qq06-flicker-free.html#doublebuffering