> For the complete documentation index, see [llms.txt](https://docs.gamesense.biz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.gamesense.biz/api-reference/callbacks.md).

# Callbacks

Register on\_update and on\_paint event handlers.

Callbacks execute Lua functions when specific events occur.

## Events

| Event       | Description                                                                            |
| ----------- | -------------------------------------------------------------------------------------- |
| `on_update` | Called when game state is updated. Runs on the game thread and supports IL2CPP access. |
| `on_paint`  | Called when a frame is rendered. Intended for rendering-related logic.                 |

## register\_callback

```lua
register_callback(event: string, callback: function)
```

Registers a handler for an event.

| Parameter  | Type       | Description                              |
| ---------- | ---------- | ---------------------------------------- |
| `event`    | `string`   | `"on_update"` or `"on_paint"`            |
| `callback` | `function` | Function to execute when the event fires |

**Example**

```lua
local counter = menu.label("Frames: 0")
local frames = 0

register_callback("on_paint", function()
    frames = frames + 1
    counter:set("Frames: " .. frames)
end)
```

An event may have multiple registered handlers.

## unregister\_callback

```lua
unregister_callback(event: string)
```

Removes **all** handlers for the specified event registered by the current script.

| Parameter | Type     | Description |
| --------- | -------- | ----------- |
| `event`   | `string` | Event name  |

```lua
unregister_callback("on_paint")
```

{% hint style="warning" %}
IL2CPP operations must run on the game thread, inside `on_update`.
{% endhint %}


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