A Hong Kong court sentenced three activists who for years organized vigils in remembrance of China’s 1989 Tiananmen Square crackdown to prison for terms ranging from 5 to over 7 years in prison on Friday in a case that is widely seen as a barometer of the city’s freedoms as Beijing clamps down on dissent.

W HEN THEY first met, Chris Patten, the last British governor of Hong Kong, took a shine to Tung Chee-hwa, who would become, in effect, his successor, as the first chief executive from 1997 of what became a Chinese Special Administrative Region.