I am currently using Bresenham\'s algorithm to draw lines but they are (of course) one pixel in thickness. My question is what is the most efficient way to draw lines of arb
Here is a paper and Delphi implementation of a modified version of Bresenham's algorithm for drawing thickened lines.
You may also want to take a look at Anti-Grain Geometry, a library for high-quality and high-performance software rendering of 2D graphics. Take a look at the demo page to get an idea of what it can do.