I am trying to Hook Cocoa API.
I know cocoa provides a public api for hooking, so it’s possible to hook the system function and retrieve information like the current font settings of the context.
I am also trying to hook that draw api from cocoa.
Can somebody point me to details on how it can be achieved. Or some references which talks about hooking of Cocoa APIs?
By Hooking , I mean “A fundamental technique of getting control over a particular piece of code execution. It provides an straightforward mechanism that can easily alter the operating system’s behavior as well as 3rd party products, without having their source code available.”
My requirement is, if any application/system is drawing something, then I want those draw instructions should first come to me. Then I cant to store those commands, for some processing later.
The term you are looking for is something like “systemwide code injection,” and Cocoa does not provide an API for any such thing. You’d need to take a look at something like mach_star or SIMBL. But honestly, this is one of those things where, if you have to ask, it’s probably a little advanced for you. Modifying other processes’ code is a gigantic PITA and even harder to do right, even with as much help as mach_star offers. If you want to see just how hard, take a look at Unsanity’s site. That’s the company that pioneered code injection on OS X, and their entire product line is based around it — and many of their programs are still not compatible with OS X 10.6.