The sentence you've seen means: "The rooster found the fox petrified/scared/ ,etc.".
That is, "The rooster saw that the fox was scared".
This pattern uses only adjectives and not adverbs. If you use adverbs, the meaning of "دیدم" will be totally different. The sentences following this pattern are a bit too formal for spoken Persian.
Some example (with adj.):
به خانه که برگشتم پنجره اتاقم را شکسته دیدم. (When I got back home, I figured that my room's window had been broken.)
دوستم را حیرت زده دیدم و احوالش را جویا شدم. (I found my friend dazzled, so I asked him how he was feeling.)
دوستم را گرمازده دیدم که پس از ساعتها سرگردانی در بیابان تازه به خانه رسیده بود. (I found my friend heat-stricken at his home after he had wandered for hours in the desert.)
Some examples (with adv.):
او را به خوبی دیدم که داشت از فروشگاه دزدی می کرد. (I saw him well, when he was shoplifting.)
آن قدر باران در جاده شدید بود که اتوموبیل جلویی را به سختی می دیدم. (The rain was so heavy I could see the front car with difficulty.)
I hope you find my explanation informative and useful.