graphicxtras.com > How to use the new live shape line segment tool in Illustrator tutorial
Above, two line segments generated by the tool in the toolbox for Illustrator in black on orange. A width profile has been added along with a stroke
It is no longer the old tool from CS6 CS5 etc, it is now a live shape tool and as such it comes with a number of new features as well as a few features that have (at the present) vanished. Live shapes is the new concept for the CC that certain paths remain editable in such as circles / rectangles and now the line has joined the live category. I mean, it was always live before as you could always stretch the line and set the angle but you will see a few differences in the features.
I generally go to the preferences section and set up the preferences for the smart guide to include most of the features. Smart guides can be very useful as well as baffling at times in that sometimes where you expect a smart guide you won't see it and in some places you will. I am certain the smart guides will grow and be added to over and over in the next few versions of AI and they are generally worth checking out. Set the transformation tools to on and construction guides. You can use them without those set on as well.
Go to the toolbar and select the line segment tool and set the stroke and width etc and add the path by clicking on a position on the artboard and then dragging the tool to another position on the artboard (near or far). OK, not much different from before. You can still use the shift key at this point to constrain the angle to 45 degrees etc but weirdly this feature appears not to be available once the artwork is there on the artboard.
You will now see a center point display (small circle) and you can click there and drag the path. If you click at the end points you will only change the angle of the path. If you use the alt along with the tool itself then a new line is created with the same size and stroke etc and it will be displayed parallel to the first and you can repeat this to create a whole load of parallel lines. It would be useful if the center point could be moved (as well as reset back) but it appears to be fixed as if the center point was flexible then you could rotate around a flexible point but at the moment that doesn't seem to be the case or perhaps break the center point from the line (as before).
You can select the end points and rotate and as you move the artwork you will see smart guides popping up saying certain distances from certain paths and not others as well as various alignments. You may or may not like that feature but personally, I think the info is useful and it is great to be able to select a certain point to stop moving the path or changing the angle. The reference point does not seem to have any use. To extend the length of the line just select either end point and stretch out to the required point or go the other way to shrink the line. You can also change the angle via the transformations panel as well as change the length and position of the path via the top bar.
The rotate can be done as before by using the selection tool and having the control just close to the end point (above etc) but with this version the shift seems not to constrain the angle (as mentioned) but you can use the transformation panel to set the value to the correct angle and that offers the range of 0 and 30 degrees etc to set the path.
This is one slight unusual disappearance as the tilde trick feature was quite useful where the paths would be generated as you moved the path and you could create interesting starbursts and background effects and meshes etc but that appears to be no more. The feature is still available in some tools but not the live shape.
You can still change the stroke width, add width profiles (which is quite useful with the stretch and shrink end points) as well as brushes, effects, appearances, styles etc and the path is still a live shape. Actually unlike some of the other live tools, it does seem that there is no way to break the live aspect so all the effects are changed as the length is changed of the tool.
You will see the tool's generated path listed as a line and not a path. You can also use the fact that is a different shape and use the selection to select the same shape option to capture all the identical types though it would be nice if there was a select rectangles and select ellipses etc feature as well (sadly, not)
Use the expand command but then it just becomes a fill. The solution is to go to the object menu and select the shape option and expand (you can also do the reverse with the convert command). You can, of course, just avoid the tool altogether and use the pen tool to create two points (always useful to have a number of features to create the same sort of thing)
I like the idea of the 'live' and I would love to see it extended to the polar grid, star etc but at the same time I would love to see an option to just use them as before. I would love to see to see the tilde feature restored as that is odd to see that removed. I wish the center point would be a little more flexible and perhaps more informative as well - it is supposed to be smart. Anyway, a good addition to Illustrator CC 2015.1. If you want to see another implementation of this style of working I suggest you check out the excellent Astute Graphics' VectorScribe tool and their dynamic tool set as that comes with rings and stars and more. Affinity Designer also does a nice implementation as well.