Stephen King's best-selling book series "The Dark Tower" is closer to the big screen after the author himself confirmed the casting of Idris Elba and Matthew McConaughey.

In a tweet, King confirmed that two of Hollywood's most talented actors will be portraying the lead characters of his critically-acclaimed magnum opus.

In an interview with Entertainment Weekly, the 68-year-old American author admitted that the progress of the series' film adaptation has taken quite a while after it was passed on from different production studios.

"The thing is, it's been a long trip from the books to the film," he told the magazine, recalling how he began writing the story way back when he was still a college senior.

According to the outlet, "A Royal Affair" director Nikolaj Arcel will be helming the movie based on the book series that covers different genres ranging from horror, sci-fi, Western and fantasy.

"What Stephen King does best is mixing the everyday, or what you might call the mundane, with the fantastical. In my view, [The Dark Tower] novels are a mix between sci-fi and fantasy and modern times. That exact mix is so Stephen King," Arcel told the outlet.

The series follows the story of a gunslinger known as Roland Deschain (Elba) who travels through Mid-World to reach the tower in order to save his fallen homeland from decaying.

During his quest, he discovers the existence of the mystical man in black known as either Walter O'Dim or Walter Padick (McConaughey) who also seeks to find the same tower, which he intends to use to rule over what seems to be an infinite group of kingdoms.

While neither Arcel nor King revealed which books they intend to cover in the movie, some clues provided by the author of the book implies that changes might be coming in terms of how the story is told.

That may not sit well with fans of the book, especially those who want movie adaptations to be faithfully written based on their origins.

One thing that the film makers should consider not doing is condensing all seven books into a two-hour film because it really would not sit well with the readers.

In fact, five years ago, Den of Geek had warned producers not to do such a thing and instead combine two or three of the books. That would make the franchise last at least three movies long, without changing the story so much.

Like Den of Geek, readers might also want to experience the "tone" of the book in the flick, specifically the post-apocalyptic setting, the ka-tet's closeness, the sacrifice and redemption themes and the odd-but-effective "meta-fictional nature" of the final two books.

Plus, Stephen King should play himself.

While the "King" has participated in previous films via cameos, this particular franchise needs him to play himself just the same as he wrote his identity into the last two installments.