On Feb 21, 2011, at 03:56, Jonathan Taylor wrote:
> I am looking at the performance of my code, and have found that rather a lot
> of time is spent in [NSBitmapImageRep getBitmapDataPlanes]. This is rather
> disappointing because I had assumed this was a 'trivial' way of getting a
> pointer to the actual data store itself in the case of raster data.
> Investigation using shark appears to confirm that the call is making a copy
> of the data(?). Can anyone shed any light on what is going on and whether I
> can do anything about it?
Assuming you're running on Snow Leopard, the relevant information is in this
document:
http://developer.apple.com/library/mac/#releasenotes/Cocoa/AppKit.html
under this heading (about 60% of the way through the document):
NSBitmapImageRep: CoreGraphics impedance matching and performance notes
I think you'll find the answer to the question of why the data is being copied
in there.
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