Is it possible to show new metrics in widgets?

I need to show new metrics (readings of the articles showed on my web page, for example) in the widgets Piwik provides. Is it possible without having to create a new plugin? I’ve read about events, custom dimensions, custom variables, goals, etc. But I haven’t found the answer to my doubt.

My website has this architecture: Home, where it gives the possibility to click on Sections links, then, inside every section, it shows articles for people to click on and go to the article detail. What I need is to show in my Piwik dashboard the evolution of the visits and readings of the articles. I already can detect when an article has been read, so, when it happens, I want to send that metric to Piwik to show on the evolution widget.

Thanks in advanced.