I am working on a project that has histogram charts displayed to the user. After the first draft, the client made a request for more granularity. So in a histogram that looks something like this
They want to be able to see smaller increments if the desire
Currently, the implementation of getting these smaller increments involves using the scrollwheel to hover over the histogram, and zoom in (scroll towards the screen) and out (scroll away from the screen). I don't think this is a very good way to do it, because if someone doesn't have a scroll wheel, they can't get that granularity they desire. I would like to do something with input boxes, where the user can put in their own range and get a histogram with that range.
Since there are multiple histograms though, this might get cluttered with all the input boxes floating around.
What would be the best approach to give the customer the granularity they want while still maintaining good UX principles?