Python Menu Class

Creating our own Menu Class to use in Unreal

Menu Classes created with Python can be just as dynamic as those created in C++, we'll first start with a base class then add additional features to it

The Base Class

When creating Editor Menu Entries, this is generally what my base class looks like:

@unreal.uclass()
class PythonMenuTool(unreal.ToolMenuEntryScript):
    name = "programatic_name"
    label = "display Name"
    tool_tip = "tool tip!"
 
    def __init__(self, menu, section=""):
        """
        given a menu object and a section name, 
        initialize this python tool and add it to the menu
        """
        super().__init__()
        
        if section:
            menu.add_section(section, section)

        # Initialize the entry data
        self.init_entry(
            owner_name="custom_owner",
            menu=menu.menu_name,
            section=section,
            name=self.name,
            label=self.label,
            tool_tip = self.tool_tip
        )

        # Add this tool to the desired menu
        menu.add_menu_entry_object(self)

This class will initialize and add itself to the given menu, it won't do anything yet.

We can use the class like so in our code:

ToolMenus= unreal.ToolMenus.get()
menu = ToolMenus.find_menu("LevelEditor.MainMenu.DemoTools")
PythonMenuTool(menu)

and it will show up in our Demo Tools dropdown menu:

Declaring the Execute

To set what we want out button to do, we can override its execute function:

    @unreal.ufunction(override=True)
    def execute(self, context):
        """The Python code to execute when pressed"""
        print(f"Provided context: {context}")

It will now print a message when pressed

Declaring the Execute Condition

To control whether the menu button can run, we can override its can_execute function:

    @unreal.ufunction(override=True)
    def can_execute(self, context):
        """Can the user press this menu entry?"""
        is_ctrl_down = unreal.InputLibrary.modifier_keys_state_is_control_down(
            unreal.InputLibrary.get_modifier_keys_state()
        )
        return is_ctrl_down 

Users must now hold the CTRL key down to use our tool

Dynamic Labels

To set a dynamic label in the menu, we can override its get_label function:

    @unreal.ufunction(override=True)
    def get_label(self, context):
        """Update the Display Name"""
        is_ctrl_down = unreal.InputLibrary.modifier_keys_state_is_control_down(
            unreal.InputLibrary.get_modifier_keys_state()
        )
        return "CTRL is GO!" if is_ctrl_down  else "Press CTRL to use"

The Label will now change depending on whether the user is pressing the CTRL key: