In which cases do you translate the present progressive in English into an infinitive of a verb in Spanish?

For example, I think that in translating a phrase like "upon leaving" from English to Spanish, you use "al salir de". In what other cases would an "-ing" verb in English translate to the infinitive -ar, -er, or -ir (instead of the present progressive "-iendo" in Spanish)?



Thanks so much in advance!In which cases do you translate the present progressive in English into an infinitive of a verb in Spanish?
You must change the present progressive into infinitive when the verb is not happening in that exactly moment

Smoking is bad for you in this case the verb (smoke) is not happening then you use the infinitive form

Fumar es malo para ti