# Source code for tecplot.session

    """|Tecplot Engine| State and |Tecplot License| Management

    The `session` module contains methods used to manipulate the |Tecplot Engine|
    such as notification of a `state change` that was done such as adding or
    modifying data. It also contains methods for acquiring and releasing the
    |Tecplot License|.

    .. _state change:

    State Changes
    -------------

    State changes are the method for propagating information when an event occurs.
    A state change can be triggered by many events. Examples include: loading a
    data file, changing the color of a mesh plot, creating a new zone, or changing
    the plot type.

    In general, state changes are already handled internally after each call to the
    PyTecplot API. This can cause a script that performs many operations,
    especially those that alter data, to run slowly since the |Tecplot Engine| must
    update it's internal state every time a state change is received. To speed up
    such scripts, it may be necessary to use the `tecplot.session.suspend()`
    context. This will collect state changes for any operation performed and will
    emit the required state changes only upon exit of the context.

    Using the `tecplot.session.suspend()` context in combination with Python's
    "-OO" flag which removes many run-time checks in the PyTecplot API is the
    recommended way to run a PyTecplot script which requires faster execution
    time. The user should be aware that, when using the "-OO" flag, errors may
    not be recoverable by the |Tecplot Engine|.

    """

    from .aux_data import AuxData
    from .session import (acquire_license, clear_suspend, connect, connected, disconnect,
                          license_expiration, release_license, start_roaming, stop,
                          stop_roaming, suspend, suspend_enter, suspend_exit)
    from .state_changed import connectivity_altered, data_altered, zone_added
    from .style import Style, get_style, set_style

    import os
    import platform
    from ..tecutil import _tecutil_connector

    def tecplot_install_directory():
        """|Tecplot 360| installation directory.

        Top-level installation directory for |Tecplot 360|. This will
        typically contain configuration files and the examples directory.

        This directory is platform-dependent and will contain configuration files
        and the examples directory:

        .. code-block:: python
            :emphasize-lines: 4

            import os
            import tecplot

            installdir = tecplot.session.tecplot_install_directory()
            infile = os.path.join(installdir,'examples','SimpleData','SpaceShip.lpk')
            outfile = 'spaceship.png'
            tecplot.load_layout(infile)
            tecplot.export.save_png(outfile, 600, supersample=3)

        .. figure:: /_static/images/spaceship.png
            :width: 300px
            :figwidth: 300px
        """
        if not _tecutil_connector.connected:
            _tecutil_connector.start()
        d = _tecutil_connector.tecsdkhome
        if d:
            if platform.system() in ['Darwin', 'Mac']:
                d = os.path.normpath(os.path.join(d, '..', '..'))
            return d

    def tecplot_examples_directory():
        """|Tecplot 360| examples directory.

        Examples directory that is typically installed with |Tecplot 360|.
        This may be overridden with the TECPLOT_EXAMPLES environment variable.

        This directory is platform-dependent and by default contains the various
        examples shipped with |Tecplot 360|:

        .. code-block:: python
            :emphasize-lines: 4

            import os
            import tecplot

            examples_dir = tecplot.session.tecplot_examples_directory()
            infile = os.path.join(examples_dir,'SimpleData','F18.lay')
            outfile = 'load_example.png'
            tecplot.load_layout(infile)
            tecplot.export.save_png(outfile, 600, supersample=3)

        .. figure:: /_static/images/load_example.png
            :width: 300px
            :figwidth: 300px
        """
        d = tecplot_install_directory()
        if d:
            return os.environ.get('TECPLOT_EXAMPLES', os.path.join(d, 'examples'))