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From Cocoa with Love

by Mark Waddingham on April 23, 2014 , 11 comments

There’s lots been going on at RunRev lately development-wise. Maintenance on the 6.6 cycle has been trundling along, 7.0 with its Unicode support is rapidly maturing and in between these two things sits the project that has been my main focus for the last few months – 6.7.

The main goal of 6.7 is to rework the Mac-specific parts of the engine to use the Cocoa framework rather than the (now deprecated, and aging!) Carbon / Classic frameworks. Not only will this allow LiveCode apps to be sandboxed (there are numerous bugs in Mac’s implementation of sandboxing for Carbon apps) and thus submitted to the Mac AppStore once again but it also means that things like revBrowser work much better as the browser control can be embedded directly in the stack window.

One of the most challenging parts of porting the engine to use Cocoa has been (as far as possible!) to retain identical functionality as before. Cocoa is a very high-level framework and as such likes to do things in a very specific way. Given that LiveCode is also a very high-level framework there is a certain amount of ‘creative coding’ required to bend Cocoa around to LiveCode’s way of thinking.

For example, Cocoa will not send continuous ‘windowMoved’ messages (unlike Carbon), you only get periodic updates when the user pauses the movement. This did cause a bit of consternation, but after some googling, some hair pulling and a nifty use of an auxiliary thread and window server interrogation, LiveCode can still enjoy appropriate moveStack messages (you can see the patch for that here https://github.com/runrev/livecode/pull/613).

All-in-all though, the transition to Cocoa has been relatively smooth – a cleaner, more well-defined separation between the platform-specific part of the engine and the rest is emerging and we’re approaching parity with the non-Cocoa feature set.

Anyway I’d better get back to my 6.7 bug fix list – we’re hoping to get 6.7-dp-3 ready soon which will hopefully be the last before we start the RC cycle!

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Mark WaddinghamFrom Cocoa with Love