If that graph widget is designed for time-series data, it would need an X-axis timestamp and corresponding Y-axis value for every different sensor it renders. A timer would be used to periodically take samples, and the sample would be created with a timestamp of whenever the timer fired.
Why would the software developer(s) use the time instead of a timer to make a graph?
It’s possible they did both.
If that graph widget is designed for time-series data, it would need an X-axis timestamp and corresponding Y-axis value for every different sensor it renders. A timer would be used to periodically take samples, and the sample would be created with a timestamp of whenever the timer fired.