[QGIS-Developer] Porting Create Grid algorithm to C++

[Clemens Raffler]

Dear QGIS Developers,

lately I have been using the 'Create Grid' algorithm a lot on huge areas 
and with a rather fine grid resolution. I was not surprised that 
creating a very fine grid took a very long time as the algorithm is 
currently implemented in python.

In order to speed up my work I decided to experiment a little with C++ 
(coming from a python background) development in QGIS and ported the  
algorithm to C++ based on other native algorithms. The code is working 
very well, the grid creation process has been sped up significantly. I 
would now like to contribute the code to the QGIS project so that other 
users can benefit from the speedup.

Coming from a plugin development/ python background I have little 
experience with the processes involved with porting processing 
algorithms from python to C++ and wanted to clear some questions with 
you before opening a pull request:

- Is there any reason why certain algorithms (eg. the Create Grid alg) 
should not be available in C++?

- As I am not familiar with the processes how native processing 
algorithms get committed to the main repository (pull requests, 
prepare-commit.sh, sip, etc.), would anybody like to help/mentor/guide 
me through this process and review the code?

- Are there any special requirements on testing infrastructure for C++ 
algs which should be implemented too (I have not worked with tests so far)?

So far, my experience with porting python algs to C++ has been very good 
with Create Grid and I would like to work on other ports if everything 
goes well.

Best regards,
Clemens