Asynchronous event support#

Every attribute change may have an event callback associated with it. This example explores different connection mechanisms and different mechanisms for getting data values.

Start an EnSight session#

Launch and connect to an instance of EnSight. This example uses a local EnSight installation.

from urllib.parse import parse_qs, urlparse

from IPython.display import display
from ansys.pyensight.core import LocalLauncher
from ipywidgets import widgets

session = LocalLauncher().start()

Register an event callback#

The simplest case for registering an event callback is for a specific attribute on a specific object. This example registers an event callback to the ensight.objs.core object. Whenever the PARTS attribute changes, the callback function is called when a dataset is loaded. Every callback function includes a string that is returned as a parameter to the callback function.

partlist_disp = widgets.HTML()
display(partlist_disp)


def part_list(name: str):
    partlist_disp.value = f"Event: {name}"


session.add_callback(session.ensight.objs.core, "partlist_name", ["PARTS"], part_list)

Load a dataset#

This code loads some data included in the EnSight installation and brings up an interactive viewer for the scene.

../../_images/00_events_0.png

The callback string is grpc://.../partlist_name?enum=PARTS&uid=220. The callback is in the form of a URI, where “partlist_name” is the string from the call to the add_callback method. The name of the attribute is always returned in enum, and the ID of the object is returned in uid.

session.load_data(f"{session.cei_home}/ensight{session.cei_suffix}/data/guard_rail/crash.case")
render = session.show("remote")

Register an event callback on a class#

Events can be associated with classes as well. This code associates a callback with all part objects, listening to both the VISIBLE and COLORBYRGB attributes. The urllib module is used to parse out the returned value.

../../_images/00_events_1.png

After running this code, the cell value calls out the change in the color of the windshield.

part_disp = widgets.HTML()
display(part_disp)


def part_event(uri: str):
    p = urlparse(uri)
    q = parse_qs(p.query)
    obj = session.ensight.objs.wrap_id(int(q["uid"][0]))
    value = obj.getattr(q["enum"][0])
    part_disp.value = f"Part: {obj}, Attribute: {q['enum'][0]} Value: {value}"


attribs = [session.ensight.objs.enums.VISIBLE, session.ensight.objs.enums.COLORBYRGB]
session.add_callback("'ENS_PART'", "partattr", attribs, part_event)

session.ensight.objs.core.PARTS["hood"][0].COLORBYRGB = [1.0, 0.0, 0.0]

Trigger with the VISIBLE attribute#

This code triggers the same callback when changes are madee to the VISIBLE attribute.

../../_images/00_events_2.png
session.ensight.objs.core.parts["windshields"].set_attr(session.ensight.objs.enums.VISIBLE, True)

Trigger with a callback macro#

This code extends the previous example by using the macro mechanism to capture both visibility and RGB color values. The name string includes a mechanism for including target object values directly in the returned URI. This mechanism avoids the need to make PyEnSight calls from within a callback function. This can avoid reentrancy and performance issues. This approach is more efficient than the approach used in the previous example.

../../_images/00_events_3.png
macro_disp = widgets.HTML()
display(macro_disp)


def macro_event(uri: str):
    p = urlparse(uri)
    q = parse_qs(p.query)
    obj = session.ensight.objs.wrap_id(int(q["uid"][0]))
    obj.getattr(q["enum"][0])
    macro_disp.value = f"Part: {obj}, Attr: {q['enum'][0]} Visible: {q['visible']}  RGB: {q['rgb']}"


attribs = [session.ensight.objs.enums.VISIBLE, session.ensight.objs.enums.COLORBYRGB]
name = "partmacro?visible={{VISIBLE}}&rgb={{COLORBYRGB}}"
session.add_callback("'ENS_PART'", name, attribs, macro_event)

session.ensight.objs.core.PARTS["hood"][0].COLORBYRGB = [0.0, 1.0, 0.0]

Close the session#

Close the connection and shut down the EnSight instance.

# sphinx_gallery_thumbnail_path = '_static/00_events_3.png'
session.close()

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