Batman # 2 is also an influence, it picks up after Batman # 1 revealing Joker is alive, and this is also where the fake Batman first appeared as part of a plot connected with Joker. This particular fake Batman story is what inspired the plot in the film....
Some people think the fake Batman story in Sons of Batman #1, and Batman #664, also play some role -- if this is true, then Joker spitting venom would NOT be that far fetched as that particular idea can be found in Morrison's run (to be clear Grant Morrison also wrote these two comics that are in question). Just an idea.
However it's more than likely, Batman #1 and 2, Killing Joke, Long Halloween, and a little bit of Dark Victory....