Context.py

# Module:   Context.py | [ Language Python ]
# Author:   Gaps | sGaps | ArtGaps
# LICENSE:  GPLv3 (available in ./LICENSE.txt)
# --------------------------------------------
""" Utility module used to manage and test the GUI inside and outside krita.

    When Krita is available, CONTEXT = 'INSIDE_KRITA', and Krita's built-in
    can be used safely.

    Otherwise, CONTEXT = 'OUTSIDE_KRITA' and you won't be able to use
    Krita's functions.

    [:] Defined in this module
    --------------------------
    RUN         :: function
        It's an alias for the exec_ function defined on QApplication class.
        Use this after setup all GUI's component.

    Extension   :: class
        It's an QWidget outside Krita. Otherwise it's a Krita.Extension
        Used as base class for the PixelExtension.

    CONTEXT     :: str
        Says when the context is INSIDE_KRITA or OUTSIDE_KRITA.

    [*] Author
     |- Gaps : sGaps : ArtGaps
"""
from sys   import stderr
try:
    from krita import Extension
except ImportError:
    print( "[CONTEXT] Unable to find krita. Trying to use PyQt5 instead." , file = stderr )
    try:
        from PyQt5.QtWidgets import QWidget , QApplication
    except ImportError:
        print( "[CONTEXT] Unable to use PyQt package." , file = stderr , flush = True )
        CONTEXT   = "NO-REQUIRED-PACKAGES"
    else:
        CONTEXT   = "OUTSIDE_KRITA"
        Extension = QWidget
else:
    CONTEXT = "INSIDE_KRITA"
    RUN     = lambda _ : ()