NEW YORK — Sing out Troy, Gabriella, Sharpay and Ryan.

Even before “High School Musical” became the celluloid Holy Grail of entertainment for adolescent girls everywhere, the idea of a stage version was being contemplated by the folks at Disney.

At first, though, the Mouse House didn’t realize the popularity of its TV movie could translate into a big-budget, Broadway-style touring show. It was thinking schools and amateur groups.

“I knew there was a lot of excitement about it at the Disney Channel,” says Steve Fickinger, a Disney Theatrical vice president in charge of creating properties for licensing to schools, amateur groups and professional theaters.

“We got the rights to do a stage adaptation before it aired on television — which made us look incredibly prescient,” he says with a laugh. “Its charms were obvious. ... As the film went on to be a sensation and then a phenomenon, we realized we had a terrific opportunity on our hands.”

For those who haven’t heard of it (and there must be a handful somewhere), “High School Musical” celebrates the aspirations of high-school students — whether they are jocks, brainiacs (the musical’s term for smart kids) or thespians.

The plot concerns what happens when a jock, Troy, and a brainiac, Gabriella, try out for the annual high school musical, incurring the wrath of the school’s perennial drama-club stars, Sharpay and her twin brother, Ryan. Follow your dreams, the musical says, no matter where they may take you.

The film was first televised in January 2006 on the Disney Channel and, boom, staggering success for the movie and its subsequent, best-selling CD.

But would enthusiasm for “High School Musical” last? Fickinger wasn’t sure.

“Nobody is 100 percent certain what the shelf life of a phenomenon is,” Fickinger says. “So I was aggressive about wanting to get (a stage version) into schools as quickly as possible.”

Fickinger took what was normally a 16- to 24-month development period and compressed it into six months. A book adaptation was quickly done by David Simpatico as was a music adaptation by Bryan Louiselle, who also wrote two new songs.

By June 2006, Disney executives were watching a reading in New York of the stage version, done by young performers from various Broadway shows.

“Immediately, we could see that it had a freshness and an appeal,” Fickinger said. “Nobody in the room — because it basically was just Disney folks in the audience — was under 22 or 23. Everyone was laughing and cheering and had a lump in their throats.”

A plan was quickly put together to have the show to schools by fall 2006. So on the Web site of Music Theatre International (which licenses Disney shows) a note went up: “If you’re interested in doing it in your school or in your amateur group, please send us an e-mail.”

Disney got 15,000 e-mails, meaning interest was LARGE.

At the same time, professional companies began to show interest. So Fickinger and others devised a plan for professional productions, beginning with six theaters.

One of the first to do the show was Atlanta’s Theater of the Stars at the mammoth, nearly 4,000-seat Fox Theatre. It put together a production, directed by Jeff Calhoun, which used actors cast in New York and some 25-30 children from the Atlanta area as part of the show.

Disney was so pleased with the responses, it decided to tour the show itself — using much of the Atlanta production and again with Calhoun directing. It’s now pretty much booked through the year, and that’s besides the more than 2,000 high school and amateur productions that have been done over the past year.

“High School Musical” reminded Calhoun of his own road to a theater career.

“I was the football quarterback who also choreographed the high school musical,” recalls Calhoun, who first danced on Broadway in the early 1980s before graduating to choreography and directing. “The movie really did resonate with me. I was a mix between Troy and Ryan because I had to leave football practice on Wednesdays an hour early to go to tap-dance class.”

Calhoun said his job was physicalizing the story and songs put together by Simpatico and Louiselle. “The key, or course, is the moving lockers” — the ubiquitous storage units found in every high school and which form a prominent scenic component of the musical.

“The kiss of death for this show would have been automation. As soon as something starts to move by itself or come out of the floor, it would feel overproduced,” the director adds. “For ‘High School Musical’ to work, you have to have the feeling of ‘let’s put on a show.’ But at the same time, that’s very deceptive because it’s a very big, complicated show made to look very simple by kids just pushing around some locker units.”

Casting also is big, with more than 30 performers, most of them young. Calhoun thinks John Jeffrey Martin (Troy) and Arielle Jacobs (Gabriella) will be big stars.