[Numpy-discussion] Is numpy supposed to support the buffer protocol?
robin at alldunn.com
Tue Aug 29 01:09:35 CDT 2006
Travis Oliphant wrote:
> Christopher Barker wrote:
>> HI all,
>> line 2814, in SetDataBuffer
>> return _core_.Image_SetDataBuffer(*args, **kwargs)
>> TypeError: non-character array cannot be interpreted as character buffer
>> If I try to pass in a numpy array, while it works great with a
>> numarray array.
> This error sounds like wx is using the *wrong* buffer protocol. Don't
> use bf_getcharbuffer as it is of uncertain utility. It is slated for
> removal from Python 3000. It was meant to be used as a way to determine
> buffers that were supposed to contain characters (not arbitrary data).
> Just use bf_getreadbuffer and bf_getwritebuffer from tp_as_buffer.
I'm using PyArg_Parse($input, "t#", ...) to get the buffer pointer and
size. Is there another format specifier to use for the buffer pointer
using the other slots or do I need to drop down to a lower level API to
get it? I didn't realize there was a distinction between buffer and
character buffer. Another read of the PyArg_Parse docs with that new
fact makes things a little more clear.
Looking at the code I guess "s#" will do it, I guess I thought it would
try to coerce the object to a PyString like some other APIs do, which I
was trying to avoid, but it doesn't appear to do that, (only encoding a
unicode object if that is passed.) I think I'll take a shot at using
tp_as_buffer directly to avoid any confusion in the future and avoid the
arg parse overhead... Any other suggestions?
BTW Chris, try using buffer(RGB) and buffer(Alpha) in your sample, I
expect that will work with the current code.
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