Converting Python Images to Symbian Images for Wrappers

[yqmtooblue]

Hello,
I am working on an app that does some image procesing. I would like to do this processing in C since it runs very slowly when implemented in Python. So I want to create a wrapper such that I pass it 1 image, and it returns a string (or an integer representing the string).

The question I have is, how do I make a wrapper that takes as input a Python image object (since the function is being called from python) and converts it into a Symbian object suitable for being processed in C.

If there is another way to pass an image to the C code through a wrapper please let me know. Any help would be greatly appreciated.

[y.a.k]

You have to create a Python extension in C++.

Get full Symbian/S60 SDK from Nokia along with Carbide.c++. Then create a DLL project (read PyS60 docs chapter on extension modules). On PyS60 you have the standard Python/C API. You have to learn to use this. You can also download PyS60 sources to take a look at some s60 specific standard modules sources. The last thing to do is to learn how to perform your task using Symbian C++ APIs.

[yqmtooblue]

Hi yak,
Thanks for your reply. I already am able to create extensions (from following these instructions: http://wiki.research.nokia.com/index.php/PythonWrappers).

The only difficult part I am having is the conversion from python image wrapper to symbian image wrapper. It seems your suggestion is to view the PyS60 sources... an unpleasant task at best.

Does anyone have a more direct answer? Surely I am not the first who wished to perform image processing in C as opposed to Python!

[y.a.k]

Looking at the sources isn't so bad

Here's a part of ext/graphics/graphicsmodule.cpp file:

static CFbsBitmap *
Bitmap_AsFbsBitmap(PyObject *obj)
{
  PyObject *capi_object=PyCAPI_GetCAPI(obj,"_bitmapapi");
  if (!capi_object)
    return NULL;
  CFbsBitmap *bitmap=(CFbsBitmap *)PyCObject_AsVoidPtr(capi_object);
  Py_DECREF(capi_object);
  return bitmap;
}

This function is used for example in blit() method to convert a PyS60 image object to CFbsBitmap object (which as I believe is a Symbian bitmap).

This code is not complete, for example the PyCAPI_GetCAPI function is found in the same file but I won't copy it here. Like I said, take a look at the sources.

Of course if someone can explain it without looking at the sources, it would be great.

[phishboh]

yqmtooblue,

I'm looking to do similar things as you are. Did you have any success? If so, I'd really appreciate if you'd like to share some of your experiences so far.
I was thinking I'd start from the source code of the graphics module and continue from there, but so far I haven't been able to compile it into an extension.
You don't feel like sharing any of your source code, do you? If so, feel free to contact me!

[anechini]

I'm trying to pass CFbsBitmap from the FrameReady callback in a camera dll written in Symbian C++ to a Python script... do you guys know how should I do it?