Aruco: completed wrapping for Python bindings

[cr333]

No description provided.

[paroj]

👍

[adrianheron]

I was using the aruco bindings in your branch (thank you!) and encountered an issue with the estimatePoseSingleMarkers function. I've tried to describe it here #574

[cr333]

The bindings for estimatePoseSingleMarkers already existed before my changes, and I didn't try them myself.

[jfolz]

@cr333 Good job on finding all the stuff that I missed!
One question: Do the Dictionary properties still work with CV_PROP instead of CV_PROP_RW? I encountered some problems with accessibility from Python using the former.
I have also yet to find a good explanation for how they differ. Maybe you know more?

[cr333]

@jfolz Sorry, I'm not really familiar with the internals of the wrapping process either. My reference was http://docs.opencv.org/3.1.0/da/d49/tutorial_py_bindings_basics.html

It suggests that CV_PROP is used for fields of classes wrapped with CV_EXPORTS_W, and CV_PROP_RW for CV_EXPORTS_W_SIMPLE (small classes passed by value) or CV_EXPORTS_W_MAP (wrapped as dictionary), which is the case you're interested in.

[jfolz]

@cr333 Yes, that's my source as well and I find the explanation a bit lacking. Looking at the parser and generator code suggests that there is exactly one difference: CP_PROP_RW creates a writeable property and CV_PROP does not. You most likely don't need writeable properties for the Dictionary in Python, Java etc., but its properties are public in C++, so why not?

[paroj]

@alalek

[mshabunin]

👍