MessageBoxDrawer.cs

using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(MessageBoxBehaviour))]
public class MessageBoxDrawer : PropertyDrawer
{
    Vector2 scrollPos;

    public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
    {
        int fieldCount = 0;
        return fieldCount * EditorGUIUtility.singleLineHeight;
    }

    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        SerializedProperty type = property.FindPropertyRelative("messageType");

        SerializedProperty DialogueTextDisplay = property.FindPropertyRelative("DialogueTextDisplay");
        SerializedProperty CanvasObject = property.FindPropertyRelative("CanvasObject");
        SerializedProperty DialogueTextColor = property.FindPropertyRelative("DialogueTextColor");
        SerializedProperty DialogueString = property.FindPropertyRelative("DialogueString");

        SerializedProperty OptionText = property.FindPropertyRelative("OptionText");
        SerializedProperty OptionContent = property.FindPropertyRelative("OptionContent");
        SerializedProperty OptionEvent = property.FindPropertyRelative("OptionEvent");



        EditorGUI.BeginProperty(position, label, property);
        var indent = EditorGUI.indentLevel;
        EditorGUI.indentLevel = 0;

        var typeRect = new Rect(position.x, position.y, 500, EditorGUIUtility.singleLineHeight);
        var DialogueTextDisplayRect = new Rect(position.x, position.y + EditorGUIUtility.singleLineHeight + 8, position.width, EditorGUIUtility.singleLineHeight);
        var CanvasObjectRect = new Rect(position.x, position.y + (EditorGUIUtility.singleLineHeight + 8) * 2, position.width, EditorGUIUtility.singleLineHeight);
        var DialogueTextColorRect = new Rect(position.x, position.y + (EditorGUIUtility.singleLineHeight + 8) * 3, position.width, EditorGUIUtility.singleLineHeight);
        var DialogueStringRect = new Rect(position.x, position.y + (EditorGUIUtility.singleLineHeight + 8) * 4, position.width, EditorGUIUtility.singleLineHeight);

        EditorGUI.PropertyField(typeRect, type, new GUIContent("Message Type"));
        EditorGUILayout.Space();
        EditorGUI.PropertyField(DialogueTextDisplayRect, DialogueTextDisplay, new GUIContent("DialogueTextDisplay"));
        EditorGUI.PropertyField(CanvasObjectRect, CanvasObject, new GUIContent("CanvasObject"));
        EditorGUI.PropertyField(DialogueTextColorRect, DialogueTextColor, new GUIContent("DialogueTextColor"));
        EditorGUI.PropertyField(DialogueStringRect, DialogueString, new GUIContent("DialogueString"));


        switch ((UIMessageType)type.enumValueIndex)
        {
            case UIMessageType.Notify:
                break;
            case UIMessageType.Option:

                float offset = string.IsNullOrEmpty(DialogueString.stringValue) ? EditorGUIUtility.singleLineHeight * 2 : 0;

                //int maxT = OptionText.arraySize;
                int maxC = OptionContent.arraySize;

                //EditorGUI.indentLevel += 1;
                //for (int i = 0; i < max; i++)
                //{
                //    EditorGUI.PropertyField(OptionTextRect, OptionText.GetArrayElementAtIndex(i));
                //}
                //scrollPos = EditorGUILayout.BeginScrollView(scrollPos, GUILayout.Width(position.width), GUILayout.Height(1000));


                //var OptionTextRect = new Rect(position.x, position.y + (EditorGUIUtility.singleLineHeight + 8) * 5, position.width, EditorGUIUtility.singleLineHeight * maxT);

                //EditorGUI.PropertyField(OptionTextRect, OptionText, new GUIContent("OptionText"), true);

                var OptionContentRect = new Rect(position.x,
                                                                     position.y + (EditorGUIUtility.singleLineHeight + 8) * 5 + offset,
                                                                     position.width,
                                                                     EditorGUIUtility.singleLineHeight * maxC);
                EditorGUI.PropertyField(OptionContentRect, OptionContent, new GUIContent("OptionContent"), true);

                var OptionEventRect = new Rect(position.x,
                                                                  OptionContentRect.y + (EditorGUIUtility.singleLineHeight + 8) * (maxC + 2),
                                                                  position.width,
                                                                  EditorGUIUtility.singleLineHeight * maxC);
                EditorGUI.PropertyField(OptionEventRect, OptionEvent, new GUIContent("OptionEvent"), true);
                //EditorGUILayout.EndScrollView();

                break;
            case UIMessageType.Model:
                break;
            default:
                break;
        }

        EditorGUI.indentLevel = indent;
        EditorGUI.EndProperty();

    }
}