How to change trendline to bold on legend click ?

See more:

chart

google-api

Hi,

I have trendline for my line chart. when i click on legend the trendline should be bold and if i click again it should be normal.

For line chart its working fine same feature should apply for trendline also.

What I have tried:

I added a separate legend for trendline if hover on the legend the opacity increasing for trendline same should be apply on click of legend instead of hover.