[Personman]

Hi all,
I am a high school senior and novice OS X developer. I am attempting to create a small OSX app fro a self-directed "Senior Project" course I'm taking. What I would like to do is provide increased control over the universal access zooming feature, normall activated with cmd-opt-8 and used with cmd-opt-+ and cmd-opt-- (Or, I suppose, = and -, since you don't hold shift for zooming in).

I want to add the ability to "freeze" the screen in one position while zoomed in, so that the mouse can be moved without the screen following it. I also have some other features I'd like to add, such as saveable zoom states and cursor hiding, but those are somewhat tangential, and probably a lot easier, at least once I figure out the main part.

I've been looking around for a while, and I haven't found much in the way of direction. I doubt very much that Universal Access itself provides a way to do this, so I was thinking I'd have to find the code, or at least the methods, that it uses, and use them differently in my own code. However, I have no idea where to look for that stuff, or if it's even available.

If that is impossible, my only option seems to be to write it from scratch, possibly using the methods of game developers, who mess with the display a lot. However, I also don't know where to find the methods that control the general output to the screen, or exactly what messing with them would entail.

Any suggestions or ideas would be greatly appreciated, including arguments for why all these approaches are wrong, or why the entire project is impossible. It seems like it should be doable, and I'm fairly determined, but if i should stop wasting my time right now, let me know.

Thanks a lot!

[Catfish_Man]

Well, assuming you can't hax0r Universal Access (maybe look into using APE?), you could do something like read in the framebuffer, modify it, and then display the modified version in a fullscreen window. Of course then the image you were reading in would be covered... so I guess that wouldn't work too well. I seem to remember some screensavers that would distort the image behind them, maybe look into how those worked.

[Chuckit]

There's no public API for the functionality. Running nm CoreGraphics | grep -i zoom on CoreGraphics reveals some promising functions that could probably do what you want if you figure them out. If hashing out undocumented API isn't your thing, the easiest technique would just be to simulate the effect yourself as you said. I don't think either way is going to be particularly easy, though.