MonoGame.Extended/Source/MonoGame.Extended.Gui/Controls/CheckBox.cs

using Microsoft.Xna.Framework;

namespace MonoGame.Extended.Gui.Controls
{
    public class CheckBox : CompositeControl
    {
        public CheckBox()
        {
            _contentLabel = new Label();
            _checkLabel = new Box {Width = 20, Height = 20};

            _toggleButton = new ToggleButton
            {
                Margin = 0,
                Padding = 0,
                BackgroundColor = Color.Transparent,
                BorderThickness = 0,
                HoverStyle = null,
                CheckedStyle = null,
                PressedStyle = null,
                Content = new StackPanel
                {
                    Margin = 0,
                    Orientation = Orientation.Horizontal,
                    Items =
                    {
                        _checkLabel,
                        _contentLabel
                    }
                }
            };

            _toggleButton.CheckedStateChanged += (sender, args) => OnIsCheckedChanged();
            Template = _toggleButton;
            OnIsCheckedChanged();
        }
        
        private readonly Label _contentLabel;
        private readonly ToggleButton _toggleButton;
        private readonly Box _checkLabel;

        protected override Control Template { get; }

        public override object Content
        {
            get => _contentLabel.Content;
            set => _contentLabel.Content = value;
        }

        public bool IsChecked
        {
            get => _toggleButton.IsChecked;
            set
            {
                _toggleButton.IsChecked = value;
                OnIsCheckedChanged();
            }
        }

        private void OnIsCheckedChanged()
        {
            _checkLabel.FillColor = IsChecked ? Color.White : Color.Transparent;
        }
    }
}