[Openmcl-devel] Advice needed: best way to fram a Lisp array into an ns-image
ron at awun.net
Fri Jan 18 19:10:42 PST 2008
On Jan 18, 2008, at 6:50 PM, R. Matthew Emerson wrote:
> On Jan 18, 2008, at 8:15 PM, Ron Garret wrote:
>> What is the easiest way to fram a Lisp array of numbers representing
>> pixel data into an ns-image object? The best I've been able to come
>> up with is:
>> 1. Create the NSImage and initialize it with initWithSize
>> 2. Create an NSData object and stick the pixel data into it.
>> 2. Create an NSBitMapImageRep and initialize it with (deep
>> 3. Add the NSBitMapImageRep to the NSImage using addRepresentation:
>> But that seems horribly clunky compared to how easy everything else
>> having to do with images is turning out to be. Is there a better way
>> to do this?
>> (BTW, the only reason I really need to do this is that
>> and setPixel:atX:y:: are gawdawful slow, like a thousand times slower
>> than an aref. If there's a fast way to access pixels directly from a
>> NSBitMapImageRep then I can just use that. But it seems like there's
> When using that really long initWithBitmapDataPlanes:... method, you
> have two options. You can pass NULL as the first argument, and
> memory for the bitmap will be allocated and owned by the
> NSBitmapImageRep instance. You can get a reference to the bitmap
> with the bitmapData method, and read/modify the data with CCL's
> foreign memory accessors (%get-unsigned-byte, whatever...)
> Alternatively, if you already have the image data somewhere, you can
> pass initWithBitmapDataPlanes:... a pointer to it. However, you
> must ensure that the data sticks around as long as the
> NSBitmapImageRep instance does. But, if you've got a regular lisp
> array with the image data in it, there's no way to pass a pointer to
> said array to foreign code.
> There is a function called CCL:MAKE-HEAP-IVECTOR that might be
> useful in this circumstance. MAKE-HEAP-IVECTOR returns both a
> macptr and a (one-dimensional) lisp array which share the same
> memory. (I don't know offhand what, if any, performance price there
> would be to pay if you made a 2-D array displaced to the 1-D heap
> ivector.) The GC won't move the heap ivector around, so it's safe
> to reference from foreign code. On the other hand, you have to call
> DISPOSE-HEAP-IVECTOR to free it.
> Maybe something I wrote here will give you an idea.
That's pretty much what I'm doing, so I guess that means I'm kinda on
the right track. Good to know.
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