I was about to post the way I thought but even as I typed it, I realised more problems. This really is a complicated request, but perhaps it could work like this.
You can only use this transition with rooms the exact same size so the engine can automatically use the same x or y coordinates (depending on up/down or left/right scrolling) of the previous room. That's the way it would work in a Zelda style game anyway, as rooms are more like particular squares on a grid.
Another style would be, the way I'm guessing you originally meant with SQ, only left/right scrolling. In this case, only the height of the backgrounds would need to be the same.
The much more complicated but much more customisable way would be to be able to specify whether you want the room to "scroll" to the character, or to specified coordinates. I must admit, scrolling dependant on where the character is seems very complicated to me because unless there's a walk behind behind rooms, you would need to show the character moving between the rooms (otherwise, it'd look odd with him just appearing in the room a few steps away). In that case, I think it'd be better to have one large background with the screen set to specific coordinates until you moved to a region on the edge of particular areas.
I hope that wasn't all nonsense...
You can only use this transition with rooms the exact same size so the engine can automatically use the same x or y coordinates (depending on up/down or left/right scrolling) of the previous room. That's the way it would work in a Zelda style game anyway, as rooms are more like particular squares on a grid.
Another style would be, the way I'm guessing you originally meant with SQ, only left/right scrolling. In this case, only the height of the backgrounds would need to be the same.
The much more complicated but much more customisable way would be to be able to specify whether you want the room to "scroll" to the character, or to specified coordinates. I must admit, scrolling dependant on where the character is seems very complicated to me because unless there's a walk behind behind rooms, you would need to show the character moving between the rooms (otherwise, it'd look odd with him just appearing in the room a few steps away). In that case, I think it'd be better to have one large background with the screen set to specific coordinates until you moved to a region on the edge of particular areas.
I hope that wasn't all nonsense...