Python Usage Examples

Creating Custom Stage Column Delegates

A custom StageColumnDelegate can be created by subclassing from AbstractStageColumnDelegate and implementing the abstract methods. Here’s an example from the built-in VisibilityColumnDelegate. For more details, please refer to omni.kit.widget.stage.VisibilityColumnDelegate.

class VisibilityColumnDelegate(AbstractStageColumnDelegate):
    """The column delegate that represents the visibility column"""

    def __init__(self):
        super().__init__()
        self.__visibility_layout = None
        self.__items_sort_policy = VisibilityColumnSortPolicy.DEFAULT
        self.__stage_model: StageModel = None

    def destroy(self):
        if self.__visibility_layout:
            self.__visibility_layout.set_mouse_pressed_fn(None)
            self.__visibility_layout = None

        self.__stage_model = None

    @property
    def initial_width(self):
        """The width of the column"""
        return ui.Pixel(24)

    def build_header(self, **kwargs):
        """Build the header"""
        stage_model = kwargs.get("stage_model", None)
        self.__stage_model = stage_model
        self.__initialize_policy_from_model()
        if stage_model:
            self.__visibility_layout = ui.HStack(style=_get_header_styles())
            with self.__visibility_layout:
                ui.Spacer()
                with ui.VStack(width=0):
                    ui.Spacer()
                    ui.Image(width=22, height=14, name="visibility_header", style_type_name_override="TreeView.Header")
                    ui.Spacer()
                ui.Spacer()

            self.__visibility_layout.set_mouse_pressed_fn(self.__on_visiblity_clicked)
        else:
            with ui.HStack(style=_get_header_styles()):
                ui.Spacer()
                with ui.VStack(width=0):
                    ui.Spacer()
                    ui.Image(width=22, height=14, name="visibility_header", style_type_name_override="TreeView.Header")
                    ui.Spacer()
                ui.Spacer()

    async def build_widget(self, _, **kwargs):
        """Build the eye widget"""
        item = kwargs.get("stage_item", None)
        if not item or not item.prim or not item.prim.IsA(UsdGeom.Imageable):
            return

        with ui.ZStack(height=20, style=_get_widget_styles()):
            # Min size
            ui.Spacer(width=22)
            # TODO the way to make this widget grayed out
            ui.ToolButton(item.visibility_model, enabled=not item.instance_proxy and item.active, name="visibility")

    @property
    def order(self):
        # Ensure it's always to the leftmost column except the name column.
        return -101

    @property
    def sortable(self):
        return True

    def on_stage_items_destroyed(self, items: List[StageItem]):
        pass

    @property
    def minimum_width(self):
        return ui.Pixel(20)

    @property
    def resizable(self):
        return False

Registering Stage Column Delegates

StageColumnDelegateRegistry.register_column_delegate can be used to register a custom StageColumnDelegate, as shown below. It’s important to keep the returned subscription object alive, otherwise the registration will be immediately deregistered.

# Register column delegates
self._name_column_sub = StageColumnDelegateRegistry().register_column_delegate("Name", NameColumnDelegate)
self._type_column_sub = StageColumnDelegateRegistry().register_column_delegate("Type", TypeColumnDelegate)
self._visibility_column_sub = StageColumnDelegateRegistry().register_column_delegate("Visibility", VisibilityColumnDelegate)

Deregistering Stage Column Delegates

Unlike registering, to deregister a StageColumnDelegate, there’s no explicit API calls required. The delegate will automatically be deregistered when the subscription object is destroyed. For example:

self._visibility_column_sub = None
self._type_column_sub = None
self._stage_open_sub = None