Accessing UI Elements at Runtime

Once a UI canvas loads, you can communicate with its UI elements at runtime by creating Script Canvas graphs, Lua scripts or by using EBuses directly from C++.

Communicating with components attached to other UI elements

You can communicate with a UI element only after it has been activated. If you have a Script Canvas graph or Lua script attached to a UI element that needs to get or set information on another UI element or its owning UI canvas, your script should wait until all UI elements activate and their parent and UI canvas references are initialized. It is recommended to connect to the UI Activation bus and wait for the In-game Post-activate event before requesting the relevant information.

Important:
To ensure that UI elements are not accessed before they have been activated, connect to the UI Activation bus and subscribe to the In-game Post-activate event, which only executes after all UI elements activate and their parent and UI canvas references are initialized.

The following example shows how to use the UI Initialization bus in a Lua script attached to a UI element.

function samplescript:OnActivate()
    -- Connect to the UI Initialization bus to receive events
    self.initializationHandler = UiInitializationBus.Connect(self, self.entityId);
end

function samplescript:InGamePostActivate()
    -- All UI elements have now been activated and their parent and UI canvas references initialized
    self.initializationHandler:Disconnect()
    self.StartButtonHandler = UiButtonNotificationBus.Connect(self, self.Properties.StartButton)
end

The following example shows how to use the UI Initialization bus in a Script Canvas graph attached to a UI element.

UI Activation Node