ndv.views #

def call_later(msec: int, func: Callable[[], None]) -> None:
    """Call `func` after `msec` milliseconds.

    This can be used to enqueue a function to be called after the current event loop
    iteration.  For example, before calling `run_app()`, to ensure that the event
    loop is running before the function is called.

    Parameters
    ----------
    msec : int
        The number of milliseconds to wait before calling `func`.
    func : Callable[[], None]
        The function to call.
    """
    ndv_app().call_later(msec, func)

def get_array_canvas_class(backend: str | None = None) -> type[ArrayCanvas]:
    """Return [`ArrayCanvas`][ndv.views.bases.ArrayCanvas] class for current canvas backend."""  # noqa: E501
    _backend = canvas_backend(backend)
    if _backend not in CANVAS_PROVIDERS:  # pragma: no cover
        raise NotImplementedError(f"No canvas backend found for {_backend}")
    return CANVAS_PROVIDERS[_backend].array_canvas_class()

def get_array_view_class() -> type[ArrayView]:
    """Return [`ArrayView`][ndv.views.bases.ArrayView] class for current GUI frontend."""  # noqa: E501
    return ndv_app().array_view_class()

def get_histogram_canvas_class(backend: str | None = None) -> type[HistogramCanvas]:
    """Return [`HistogramCanvas`][ndv.views.bases.HistogramCanvas] class for current canvas backend."""  # noqa: E501
    _backend = canvas_backend(backend)
    if _backend not in CANVAS_PROVIDERS:  # pragma: no cover
        raise NotImplementedError(f"No canvas backend found for {_backend}")
    return CANVAS_PROVIDERS[_backend].histogram_canvas_class()

def process_events() -> None:
    """Force processing of events for the application."""
    ndv_app().process_events()

def run_app() -> None:
    """Start the active GUI application event loop."""
    ndv_app().run()

def set_canvas_backend(backend: Literal["pygfx", "vispy"] | None = None) -> None:
    """Sets the preferred canvas backend. Cannot be set after the GUI is running."""
    if _APP:
        raise RuntimeError("Cannot change the backend once the app is running")
    if backend is None:
        os.environ.pop(CANVAS_ENV_VAR)
    else:
        os.environ[CANVAS_ENV_VAR] = CanvasBackend(backend).value  # validate

def set_gui_backend(backend: Literal["jupyter", "qt", "wx"] | None = None) -> None:
    """Sets the preferred GUI backend. Cannot be set after the GUI is running."""
    if _APP:
        raise RuntimeError("Cannot change the backend once the app is running")
    if backend is None:
        os.environ.pop(GUI_ENV_VAR)
    else:
        os.environ[GUI_ENV_VAR] = GuiFrontend(backend).value  # validate