The question is on the 'wenn'-clause of this sentence, which is from 'Kinder auf der Landstraße' by Kafka.
Die stark durchbrochenen Vorhänge bauschten sich im warmen Wind, und manchmal hielt sie einer, der draußen vorüberging, mit seinen Händen fest, wenn er mich besser sehen und mit mir reden wollte.
The Muirs translation goes like this:
The coarse-mesh window curtains bellied in the warm wind and many a time some passer-by outside would stay them with his hands (a) as if he wanted to see me better and speak to me.
where '(a)' was inserted by me.
From grammar books, however, I learned that 'wenn' meant 'if' or 'when' while 'als wenn' or 'als ob' meant 'as if.' On this view, the 'wenn'-clause should mean:
(b) when (or if) he would (or wanted to) see me better and speak to me.
Question: Does the 'wenn'-clause mean (a) or (b)?
If it means (a) in spite of what grammar books say, please explain what in the sentence signaled that this particular instance of 'wenn' should be understood as 'als ob'/'als wenn' and how one could unambiguously say (b) in German. Thanks.