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How to efficiently browse OpenCV repository to understand the code?

I am relatively new to coding and I apologize if my questions are straightforward to you.
I am trying to understand OpenCV code to be able to add my contributions (mainly converting 2D tools to 3D as it would be useful for my machine learning projects and for medical projects). There is also some extra-curiosity since I like to understand how things work.
1) On the example of the GaussianBlur method. What happens when I call it in Python? Namely, how the Python code is bind to the C++ one? When I browse the repository, there are all C++ files, and I do not find where it is done. When I installed cv2 with pip all was automatic, but I would like to understand the process.
2) if I want to understand the whole GaussianBlur algorithm, I am also not familiar with C++ browsing, so how should I proceed to retrieve what files are used (methods and also inherited classes).
I've found on another answer that https://github.com/opencv/opencv/blob/9c23f2f1a682faa9f0b2c2223a857c7d93ba65a6/modules/imgproc/src/smooth.cpp#L4085 contains the method, but how can I find any method on my own? Why isn't it in the master folder but in the blob folder? How to find then the other methods or classes called by this one?
3) this is more a curiosity question since I am not familiar with makefiles, but when is done the binding between Python and C++? When I install OpenCV with pip it is done automatically, but I would like to understand the process.
Thanks a lot for your answers! I would appreciate any tutorial since I've googled a lot before asking, of course, but did not find what could help me on my own.

In C++ you have to download the library and link them in the compilation and linking process (when creating an executable from source code).
The C++ bind is done with python.h library for c++. using this binding OpenCV module is created for python.
For learning gaussian blur, etc. you can learn image processing.
The methods of Opencv are kept in their respective files. like opencv2/highgui.hpp for OpenCV GUI like imshow. you can import them to C++ with #include <opencv2/highgui.hpp>(the methods are separated to different files to reduce importing unnecessary methods).
CMake is like a scripting language(its a tool) where you can write a script on how the tool should build the executable from source code.
The starter tutorial is Here

How to capture screen on Wayland(Gnome) in Python code?

I'm trying to capture my screen using Python because I'll use it on OpenCV, but I couldn't find a way to make it work on Gnome, since Gnome uses Wayland and all libraries that I've found only work with X11.
For now I'm not considering change my interface. I'm searching a solution to this problem.
Does someone know a solution?
To be more specific, I'll use the images to train an AI and so I need they continuously.
EDIT:
I've found this but how can I pass frames to OpenCV in Python instead of save a video file?

The proper way to do screencasting these days is by using the Screencast portal, which is part of XDG desktop portals and is already supported by GNOME, KDE, wlroots (and more). As an added advantage, this will also work in containerized formats like Flatpaks.
You can find an example on how to do screencasting in Pyhon using this snippet, created by one of the Mutter maintainers. If you look for parse_launch(), you will see a GStreamer pipeline which you can modify to include the GStreamer OpenCV elements that can do the processing for you.
Note: in your edit, you link to a predecessor of that portal, which is GNOME-specifc, internal API, so I wouldn't rely on it ;-)

how to control ImageJ from Python 3.4.2

I am trying to use Python 3.4.2 to control ImageJ
what I want to do is from python code , I want to sent orders to imageJ to analayse some images, detecting edges, contrast, noise etc
there is a similar question here
How to connect ImageJ to python?
but there is no answer, like "install this, and control the Find Edges button with this command"
I wonder how can I do that, can somebody help me
I have found this link, and this link, and they say that it is possible by using "import ij" but there is no ij library that I can use or install.
also ImageJ website states in "How can I call ImageJ from my software?" that "If your software is written in another language such as C or Python, there are many ways to integrate Java functionality. You must choose which one is best for your particular requirements." but there are no specifics
this Google webpage says that with "py4ij" I can control imagej with python "Py4IJ - Python for ImageJ - plugin and IDE that allows Python and Jython access to the ImageJ"
but I am not sure how to run it, Help
as an alternative to Imagej is Fiji but I am not sure if python can control it or I have to use Fiji, and Fiji tutorial
my last alternative is Using OpenCV for image processing but I actually need to use ImageJ or Fiji, so OpenCV is not a valid answer
thanks
EDIT
according to the first answer, it suggest to write a CellProfiler's RunImageJ module, but my question is should I have to install CellProfiler? from here, following the examples here and here and running the module
or should I follow the native Python idea from this link
in any case the first answer link talks about Jython, but I can not use Jython, the latest version of it is based on python2.7 and I am using 3.4, and there is no development for jython 3.x
help

Integration of Python with ImageJ was recently discussed on the new ImageJ forum; see the Python scripting thread.
While it focuses on calling native-code-wrapped Python modules such as NumPy from ImageJ, the reverse direction (calling ImageJ from Python) is also addressed by some of the solutions, particularly CellProfiler's RunImageJ module. As discussed there, a dedicated programmer could start there and champion a more general solution for the benefit of the community.
In general, this issue is discussed on the ImageJ wiki on the Python page, particularly the section on limitations.

Using python to convert PNG's into PDF's

I want to write a python script to convert PNG's into 2-page pdfs (i.e. 2 PNGs per PDF). The software needs to run on both a Mac and Windows 7.
My current solution is using ReportLab, but that doesn't install easily on a Mac. According to its website, it only has a compiled version for Windows. It has a cross-platform version that requires a C compiler to install.
Is there a better way to do this (so that I don't have to install a C compiler on the Mac)? Should I use a different library, or a different language entirely? As long as I can call the program from a python script, I could use any language for the pdf creation. Or, is there a very straightforward (i.e a non-programmer could install it) C compiler that I could install on a Mac?
What do you recommend?

The unix program convert can help you for conversion.
convert file.png file.pdf
But you said you want to have it under windows too. PIL imaging library has a PDF module. you should try a simple
pilconvert file.png file.pdf
to put more than one image you can play with the library which is quite flexible for resizing, stitching, etc. It is also available for mac and windows
Update 2011-02-15
On my macosx, I have installed reportlab without difficulties.
% sudo easy_install reportlab
Searching for reportlab
Reading http://pypi.python.org/simple/reportlab/
Reading http://www.reportlab.com/
Best match: reportlab 2.5
Downloading http://pypi.python.org/packages/source/r/reportlab/reportlab-2.5.tar.gz#md5=cdf8b87a6cf1501de1b0a8d341a217d3
Processing reportlab-2.5.tar.gz
So you could use a combination of PIL and Reportlab for your own needs.

Reportlab is one of the good tools for generating pdfs. If you can use it for your purposes, it is better to stick with it. For installation on MAC, I see that darwinports have a port for Reportlab called py-reportlab. Follow the instructions to install it using portage, it will install the dependencies by itself.

PyCairo could be a good alternative. You'll have full control and less dependencies, but reportlab is a lot simplier.

Why anyone hasn't tried this??
If you are not much concern about the quality, try the following solution.
import PIL.Image
filepath = "temp.png"
newfilename = 'our.pdf'
im = PIL.Image.open(filepath)
im.save(newfilename, "PDF", quality=100)

Converting a PDF to a series of images with Python

I'm attempting to use Python to convert a multi-page PDF into a series of JPEGs. I can split the PDF up into individual pages easily enough with available tools, but I haven't been able to find anything that can covert PDFs to images.
PIL does not work, as it can't read PDFs. The two options I've found are using either GhostScript or ImageMagick through the shell. This is not a viable option for me, since this program needs to be cross-platform, and I can't be sure either of those programs will be available on the machines it will be installed and used on.
Are there any Python libraries out there that can do this?

ImageMagick has Python bindings.

Here's whats worked for me using the python ghostscript module (installed by '$ pip install ghostscript'):
import ghostscript
def pdf2jpeg(pdf_input_path, jpeg_output_path):
args = ["pdf2jpeg", # actual value doesn't matter
"-dNOPAUSE",
"-sDEVICE=jpeg",
"-r144",
"-sOutputFile=" + jpeg_output_path,
pdf_input_path]
ghostscript.Ghostscript(*args)
I also installed Ghostscript 9.18 on my computer and it probably wouldn't have worked otherwise.

You can't avoid the Ghostscript dependency. Even Imagemagick relies on Ghostscript for its PDF reading functions. The reason for this is the complexity of the PDF format: a PDF doesn't just contain bitmap information, but mostly vector shapes, transparencies etc.
Furthermore it is quite complex to figure out which of these objects appear on which page.
So the correct rendering of a PDF Page is clearly out of scope for a pure Python library.
The good news is that Ghostscript is pre-installed on many windows and Linux systems, because it is also needed by all those PDF Printers (except Adobe Acrobat).

If you're using linux some versions come with a command line utility called 'pdftopbm' out of the box. Check out netpbm

Perhaps relevant: http://www.swftools.org/gfx_tutorial.html