Did Mesa’s Sign Code violate the First Amendment?

Edward Salib owned a Winchell’s Donut House in Mesa, Arizona. To attract customers, he displayed large signs in his store window. The city ordered him to remove the signs, because they violated its Sign Code, which prohibited covering more than 30% of a store’s windows with signs. Salib sued, claiming that the Sign Code violated his First Amendment free speech rights. The trial court gave summary judgment for Mesa, and the store owner appealed.