__init__.py

bl_info = {
    "name": "Blender G'MIC Add-on",
    "author": "Jonathan-David Schröder",
    "blender": (2, 80, 0),
    "version": (0, 0, 2),
    "category": "Object",
}

import os
import sys
import platform

# TODO ensure that globals are tolerated in Blender3d python scripting guidelines..
__GMIC_ADDON_ROOT_PATH = os.path.abspath(os.path.dirname(__file__))
__GMIC_FILTERS_JSON_PATH = os.path.join(__GMIC_ADDON_ROOT_PATH, "assets", "gmic_filters.json")
__GMIC_LOADED__ = False
__GMIC_PY_RELATIVE_LIBS_DIR = "-".join([platform.system().lower(), platform.architecture()[0]])

def register():
    print("Registering " + bl_info["name"])
    if not load_gmic_binary_library():
        print("Failed loading G'MIC binary library :-(")
    else:
        import gmic
        print(dir(gmic))
        generate_nodes_from_gmic_filters(load_gmic_filters())

def unregister():
    print("Unregistring " + bl_info["name"])

def load_gmic_binary_library():
    global __GMIC_LOADED__

    if __GMIC_LOADED__:
        return True

    __GMIC_LOADED__ = False

    import os
    import sys
    libdir = os.path.join(__GMIC_ADDON_ROOT_PATH, __GMIC_PY_RELATIVE_LIBS_DIR)
    if libdir not in sys.path:
        sys.path.insert(0, libdir)
    print("Added libdir to sys.path:", libdir)

    try:
        print("trying gmic import")
        import gmic
        print("gmic import worked")
        __GMIC_LOADED__ = True
    except ImportError as err:
        raise ImportError("Cannot load G'MIC binary python module at {}. Details: {}".format(libdir, sys.exc_info()[0]))

    try:
        type(gmic.Gmic) == type
    except AttributeError as err:
        raise ImportError("G'MIC binary Python module was loaded improperly from {} and is without symbols. Details: {}".format(libdir, sys.exc_info()[0]))

    return __GMIC_LOADED__

def load_gmic_filters():
    import json
    # TODO add cache? // mtime check?
    filters_json = None
    # TODO catch exception and make a nice error pop-in if open this file fails
    with open(__GMIC_FILTERS_JSON_PATH) as f:
        filters_json = f.read()
    return json.loads(filters_json)

def generate_nodes_from_gmic_filters(gmic_filters_dict):
    print("Loaded gmic_filters JSON overview:", gmic_filters_dict["format_version"], gmic_filters_dict["gmic_version"], "categories:", len(gmic_filters_dict["categories"]))
    print("<STUB nodes should be generated from filters here>")
    # TODO foreach loop on dict, create 1 node by filter