Save gvis object as png image

I wanted to save the object gvis

as .png

file

Gauge <-  gvisGauge(CityPopularity,
options=list(min=0, max=800, greenFrom=500,
greenTo=800, yellowFrom=300, yellowTo=500,
redFrom=0, redTo=300, width=400, height=300))
plot(Gauge)

print(Gauge, tag="chart", file="Gauge.html")

      

        
        
        
      

    

I can save them as a file .html

- I need them to be saved as .png

. How to save diagrams created from googleVis

as image ( .png

). I wanted to do this inside R.