so this is simply a snapping tool to aid those who work with blueprints of vehicles, the idea being that blueprints of cars are usually black lines on a white background, to make for more accurate and speedy tracing of lines, snap the cursor to the colour value 0,0,0, and that's it, of course you could add a color option, to choose a different color than black and you could make it so that the user clicks the start and end of a line and the program creates a curve identical to the one in the image being traced.
