When I am on a dinner date with a girl, how can I communicate to her that I am annoyed and feel disrespected when she unnecessarily uses her phone to send text messages to her friends?

(My focus is on unnecessary texting. I have been on dates with girls who have had to respond to work-related matters on emails with their phones, and this doesn't bother me at all.)

When this happens, I just sit there quietly and wonder to myself,

" ... wow ... is she that bored on this date?"

or,

" ... that's kind of rude ... does she do this on her other dates, too?"

I put in considerable effort to plan these dates: I make reservations, I go to the gym all week before the date, I get a decent haircut, and I try to dress nicely.

I have always paid for dates and never asked a girl to split the bill with me, even if they spent much of the date texting other people.

(Money is not much of an issue; I pick up the tab as one way to demonstrate that I try and be a good date.)

Most recently, I was on a date with someone, and it happened yet again:

This girl not only texted frequently but also spotted someone in the restaurant who was supposedly "famous on YouTube" -- and so she spent part of our date trying to snap a photo of him with her phone, and also tried to get his attention, to say hello. I feel I have no self-respect and am letting someone waste my time.

Instead of sitting there quietly and feeling insulted, I want to know how I can tell my date to not use her phone unnecessarily, without ruining any good vibes we have during the date. This seems like a pretty tough thing to do, because I've never actually tried being assertive in these situations, and I'm afraid I'll just act out badly and say something like, "you know what, put your fking phone away, or else I'm leaving", which would of course ruin any chances of us going out again (I think).