Neg_Utils/NEG/UI/UnityUi/Editor/OverridableNavigationDrawer.cs

using NEG.UI.UnityUi.Buttons;
using NEG.Utils.Serialization;
using UnityEditor;
using UnityEditor.UIElements;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.UIElements;
using ObjectField = UnityEditor.Search.ObjectField;

using Toggle = UnityEngine.UIElements.Toggle;

namespace NEG.UI.UnityUi.Editor
{
    [CustomPropertyDrawer(typeof(OverridableNavigation))]
    public class OverridableNavigationDrawer: PropertyDrawer
    {
        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            EditorGUI.BeginProperty(position, label, property);

            // Draw label
            position = EditorGUI.PrefixLabel(position, GUIUtility.GetControlID(FocusType.Passive), label);

            // Don't make child fields be indented
            int indent = EditorGUI.indentLevel;
            EditorGUI.indentLevel = 0;

            // Calculate rects
            var amountRect = new Rect(position.x, position.y, 200, position.height);
            var unitRect = new Rect(position.x + 35, position.y, 200, position.height);

            // Draw fields - pass GUIContent.none to each so they are drawn without labels
            EditorGUI.PropertyField(amountRect, property.FindAutoPropertyRelative(nameof(OverridableNavigation.Override)), GUIContent.none);
            EditorGUI.PropertyField(unitRect, property.FindAutoPropertyRelative(nameof(OverridableNavigation.Selectable)), GUIContent.none);

            // Set indent back to what it was
            EditorGUI.indentLevel = indent;

            EditorGUI.EndProperty();
        }

        public override VisualElement CreatePropertyGUI(SerializedProperty property)
        {
            var container = new VisualElement()
            {
                style =
                {
                    paddingLeft = 3,
                    paddingRight = -2,
                    flexDirection = FlexDirection.Row,
                    justifyContent = Justify.SpaceBetween
                }
            };

            string name = property.name;
            if (name.Length > 0)
            {
                name = $"{char.ToUpper(name[0])}{name[1..]}";
            }

            var innerContainer = new VisualElement()
            {
                style =
                {
                    flexDirection = FlexDirection.Row,
                    justifyContent = Justify.SpaceBetween,
                    marginRight = 2,
                    flexGrow = 1
                }
            };

            var label = new Label(name);

            var enabler = new Toggle();
            enabler.BindProperty(property.FindPropertyRelative("<Override>k__BackingField"));
            
            var field = new ObjectField()
            {
                style =
                {
                    flexGrow = 100
                }
            };

            var selectableField = property.FindAutoPropertyRelative(nameof(OverridableNavigation.Selectable));

            field.BindProperty(selectableField);
            field.objectType = typeof(Selectable);
            
            innerContainer.Add(label);
            innerContainer.Add(enabler);

            container.Add(innerContainer);
            container.Add(field);

            container.RegisterCallback<GeometryChangedEvent>(_ =>
            {
                var panel = container.panel;
                var size = panel.visualTree.contentRect.size;
                
                // magic value measured with ruler, may change in the future!
                field.style.maxWidth = size.x * 0.55f + 15;
            });
            
            field.SetEnabled(enabler.value);
            enabler.RegisterValueChangedCallback(v =>
            {
                field.SetEnabled(v.newValue);
            });
            
            return container;
        }
    }
}