Aaaaargh!! I just noticed in a comment, not the actual question, that the line must be curved, so ignore the first 3 answers & skip beyond the horizontal line.
Since I totally misunderstood your question 2 years ago, here's an answer to the real question. If you have solved it by now, please post and accept an answer, to help others who read this in future.
HTML5 Canvas - How to Draw a line over an image background? on S.O, shows how to do in a non-Angular way, using the canvas, but it will coexist just fine with Angular.
This Angular line drawing Plunker/Fiddle shows an example.
Ngx Image Drawing would let users draw on your images - not what you want, but maybe useful to know.
How to draw a curved line between 2 points on canvas? - it's the HTML canvas again, but will work with Angular.
Reading that previous page made me realize that DuckduckGoing for
beziercurveto canvas woudl be very helpful. See, for instance, this example and the documentation. See also Canvas user's guide
In fact, just searching for
Hopefully, you will post and accept an answer, in order to help others who read this question in future (although I doubt that you will, as this is the only question that you ever asked, so I guess that you no longer visit S.E and I am talking to myself here).