Who is flirting according to Body language?

Here is a Stock image analysis (most are little spontaneous poses, making them somewhat artificial),  I ran into one that is worth giving a second look. This is one of them:

In it we see a couple in the park. The easy question is; are they both flirting, one, or none? According to SAPP systemic analysis method we start by analyzing the situation: they share an interest (spending time in the park), and from that we can infer that they are doing this for the same propuse (chill out). The Atmosphere is conducive to conversation; do not need to get too close to talk, and tone of voice can be medium to low. The proximity between the two is not accidental.

Finally, with regard to posture, she is right at your seat, even a little tense; his facial expression reaffirms this hypothesis:

The only flexed muscle on his face is the zygomatic, and lips are tight. The eyes are expressive little (She may not get the joke?)

Meanwhile, he has rested on the bench and he does has a much more relaxed expression:

His expression is a genuine smile (the corners of the mouth are stretched upward, showing teeth, crow's feet forming in his eyes, the cheekbones tighten). Is him who is flirting with her? 

A closeup on his hand subtracted intensity to this action:

The hand "dropping" on the keyboard seems to struggle between expressing an emotion and continue working. We're clear that this can not be typing or gesturing. Even his legs are in a very uncomfortable position to support the laptop...

...but trying to shorten distance (and even invade her space). Note that no physical contact, but both personal spaces overlap. How she responds to that breakthrough?

A gesture that combines perfectly with his forced smile: an "anchor" hand propping crossing legs and limit the expressiveness of your dominant hand (assuming she is right hand). 

The left hand is the "justification" to grab coffee. In short, she is only mildly interested in what he says.