The announced Batgirl movie is based on The New 52 version of the character.
Backstory...
Comissioner Gordon's teenage daughter makes a costume and decides to join Batman and Robin crimefighting, but Batman keeps pushing her away. She ends up dating Robin for a while until he is shot in the head by Joker and decides to quit being Robin and moves away for college.
Batman gets a new Robin (Jason). Joker beats him to a pulp and then blows him up with a bomb. (link - warning graphic). After Jason's death, Batman vows to go solo and never have another partner.
But Batgirl keeps pestering Batman to be his new partner and eventually they do become partners but over time he has grown romantic feelings for her, so he starts pushing her away, so she goes on solo missions, putting herself in danger which really bothers Batman. One night they have sex (link).
The next day, Joker appears at Barbara's apartment (not knowing she is Batgirl) and shoots her in the spine which causes her to be paralyzed from the waist down. He also undresses her and takes naked pictures of her to use later to torture her father Comissionor Gordon (see animated feature Batman: The Killing Joke).
Batgirl, now wheelchair bound, becomes 'Oracle', a computer hacker and superhero support unit. (Felicity in Arrow tv series is based on Oracle... Felicity even got paralyzed and was wheelchair bound... a nod to Oracle).
Recap (link)
Proposed Movie...
Barbara Gordon has just had some experimental surgery where her spine has been repaired and she is no longer paralyzed. She has just become Batgirl again, but is suffering from PTSD from being shot and paralyzed and from the sexual assault and has to deal with it while learning how to fight crime again.
This is a complicated story with mature elements. I do not know how they can tell this complicated of a story in one movie and if it is a good story for the Wonder Woman audience.
Joss Whedon did work on a Wonder Woman movie for a long time without it moving forward because he had creative differences with DC and they eventually moved on without him.