[MacRuby-devel] How to set up and retrieve returned buffer from CTFrameGetLineOrigins?

[Jordan K. Hubbard]

On May 6, 2010, at 8:03 PM, Laurent Sansonetti wrote:

> You're right, the Pointer class must be used. Sorry about the lack of documentation. Here is a snippet that might work:
> 
> # n must be defined
> origins = Pointer.new(CGPoint.type, n) # this builds a pointer to n times CGPoint
> CTFrameGetLineOrigins(frame, CFRange.new(0, n), origins)
> 
>> 2. How to access the individual CGPoints in the returned buffer? This is not an Objective-C / MacRuby array object. It is just an address to a buffer. Easy to do in C, but how to do in MacRuby?
> 
> Using Pointer#[] you can simply dereference a given slot in the pointer, as in C.
> 
> n.times { |i| p origins[i] } # should print nth points
> 
> Let me know if this works or not for you.

If it does, I can see this being a useful entry in Matt's book!

- Jordan