Hi, You are correct about the action using the line tool. But, there is the pen tool you can use. This might take a few minutes of practice to get it right, though.
So, select the pen tool and hold down the SHIFT key to make the line straight. Then, to change directions, without lifting the mouse, but letting go of the SHIFT key, change directions with the mouse then press the SHIFT key again and continue.
Using this method, you can make turns and diagonals.
Again, PRACTICE this a bit to get the hang of it.
You can also right-click a pen line and choose EDIT POINTS from the menu. This will give you a bajillion points you can pull in or out to change the line.
To be honest, I don't think this SHIFT KEY trick is a feature AT ALL. I just found that it works but is a bit wonky when trying to make diagonal turns. However, it may help you out if you can get the hang of it.