UI and signals

A signal reports an event, such as a button press. In C#, subscribe a method to the corresponding event rather than checking the button every frame.

1. Create the interface

Create a separate document with a Control root, name it Counter and save as Counter.rscene. Control elements are designed for interfaces, with dimensions, anchors and layout rules.

Counter (Control)
├── CountLabel (Label)
└── AddButton (Button)

Select the root and choose Full Rect in the Layout tools. Keep the children anchored at the top left. Set these Layout properties in the inspector:

If the inspector shows Offsets, the button's equivalent bounds are Left 32, Top 96, Right 232, Bottom 144. This document needs no camera or light.

2. Add Counter.cs

Attach Scripts/Counter.cs to the Counter root, not the button. Use this complete code:

using Reckfell;

public partial class Counter : Control
{
    private int _count;
    private Label _label = null!;
    private Button _button = null!;

    public override void _EnterTree()
    {
        _label = GetEntity<Label>("CountLabel");
        _button = GetEntity<Button>("AddButton");
        _button.Pressed += AddOne;
        _label.Text = _count.ToString();
    }

    public override void _ExitTree()
    {
        if (ReckfellObject.IsInstanceValid(_button))
            _button.Pressed -= AddOne;
    }

    private void AddOne()
    {
        _count += 1;
        _label.Text = _count.ToString();
    }
}

Save, build C# and run the current document using F6. Press the button several times: the label should show 1, 2, 3 and so on.

How the pieces connect

_count stores an integer and starts at zero. _label and _button hold child references. On tree entry, _EnterTree() finds the already constructed children and connects the handler. If you need data calculated by a child's _Ready(), use the parent's _Ready(): children may not be ready during _EnterTree().

Pressed += AddOne means “call AddOne when the button reports a press.” Write AddOne without parentheses here: you are passing an event handler rather than calling it immediately.

_count += 1 increments the counter. ToString() converts the number to text for Label.Text. private marks a field or method as internal to this class. null! allows later initialization; it does not create a Label or fix a misspelled CountLabel name.

Why the subscription has a matching removal

Pressed -= AddOne disconnects the same method connected with +=. _ExitTree() performs this cleanup: an interface removed from the level stops receiving events. IsInstanceValid() also accounts for the button being deleted separately.

Adding the same Counter back with AddChild() makes _EnterTree() reconnect the handler and preserves _count. This differs from deletion with QueueFree(): a new instance starts at zero. The _EnterTree() / _ExitTree() pair also works on reentry, when _Ready() does not repeat automatically.

Do not connect Pressed both through this code and through the editor: one press could add two. Do not subscribe every frame in _Process(). Use a named method when you need to unsubscribe; a new lambda passed to -= is not the previously connected lambda.

Check mouse and keyboard activation

1. After launch, click the button three times: the label should read 3.
2. Move focus to the button with Tab and activate ui_accept — Enter or Space by default. The counter should increase by one.
3. If the project changes built-in input actions, check ui_accept in Input Map. The button also needs an enabled focus mode.

Use Pressed for one action per activation. For a switch, use Toggle Mode and Toggled; do not reconstruct its state by counting clicks.

A separate screen or a HUD

This document is a separate screen. In a game with a moving world camera, a HUD usually goes in a CanvasLayer containing a Control tree. This keeps the camera from moving the counter off-screen.

Use containers such as VBoxContainer and HBoxContainer, plus anchors, for resizable layouts instead of scaling text with Scale.

The counter resets on each run: this example has no disk persistence. Reference: Control, Button, Label.