[Bf-committers] bpy.Image memoryview problems

[Dan Eicher]

> - An Image has float and int buffers, so we cant assume one buffer per
> image
> - An image has imbuf's for different frames of an image sequence.
>

Could add a method that returns a memory view object that deals with frames,
layers and such instead of exporting it directly or add different memory
mappings like image[frame][x][y][pixel].

Either way I'm just trying to get this to work with Lenna before attempting
to deal with more complex cases.


> - This code adds image specific buffer access in bpy_rna.c, which I
> prefer keep generic where possible.
>

The main reason I put it there (aside from the obvious of there being no
proper python image type) is so any object that inherits from bpy_struct can
export a buffer interface with a simple RNA_struct_is_a() conditional.

Lots of places this could be used -- for instance an object can export all
the mesh geometry as a (readonly) memoryview object for exporters with
python taking care of dereferencing pointers to the face/vertex structs and
whatnot. The PEP has an example with an array of pixel struct pointers which
demonstrates this.


> - adds members, increasing the size of every object/mesh/vertex
> instance (not just images)
>

Those aren't really needed -- just one way to keep track of the malloc'd
arrays for stride, etc. since there's no 'official' way to deal with them.
Could use another method to keep track of them in any case.


> - brecht's recent work on image tiles means this could be tricky to
> continue supporting in some cases??
>

I'm not familiar with his work on this.

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I did see that there is already a py_buffer implementation for simple types
(that could be adapted to use tp_as_buffer pretty easily) so all this is
really doing is expanding that for more complex types.

Don't really want to spend time on (yet another) feature that won't get
accepted so if you're happy with the ctypes/pointer thing I'll just find
something else to work on. Do kind of need py_buffers for composite pynodes
though...