概要

using System;
using System.Collections.Generic;
using System.Reflection;
using UnityEditor;
using UnityEditor.Tilemaps;
using UnityEngine;

// Tile Palette で使用できるすべてのブラシを管理するクラス
public static class GridPaletteBrushesUtils
{
    private const BindingFlags BINDING_ATTR = BindingFlags.Static | BindingFlags.Public;

    private static readonly Assembly     m_assembly = typeof( GridPaintingState ).Assembly;
    private static readonly Type         m_type     = m_assembly.GetType( "UnityEditor.Tilemaps.GridPaletteBrushes" );
    private static readonly PropertyInfo m_property = m_type.GetProperty( "brushes", BINDING_ATTR );

    public static List<GridBrushBase> brushes => m_property.GetValue( null ) as List<GridBrushBase>;
}

[InitializeOnLoad]
public static class Example
{
    static Example()
    {
        // 選択中のブラシが変更された時に呼び出される
        GridPaintingState.brushChanged += OnChanged;
    }

    [MenuItem( "Tools/Log" )]
    private static void Log()
    {
        // 選択中のブラシを取得する
        Debug.Log( GridPaintingState.gridBrush );

        // 選択中のブラシを変更する
        var brushes = GridPaletteBrushesUtils.brushes;
        var brush   = brushes.Find( c => c.name.Contains( "Line Brush" ) );
        GridPaintingState.gridBrush = brush;
    }

    private static void OnChanged( GridBrushBase brush )
    {
        Debug.Log( brush.name );
    }
}