CalcSampleWindow.cs

using UnityEditor;
using UnityEngine;

/// <summary>
/// Tools - CalcSampleWindow に追加されるウィンドウ
/// サンプリングレート、BPM、拍子からサンプル数を計算する
/// 大抵の場合サンプリングレートは44100Hzで良い
/// </summary>
public class CalcSampleWindow : EditorWindow
{
    
    private readonly GUIContent[] _popupDisplayOptions = new[]
    {
        new GUIContent("44100 Hz"),
        new GUIContent("48000 Hz"),
    };
    private int _popupIndex = 0;
    private string _bpmString = "120";
    private int _bpm = 120;
    
    private string _beatString = "4";
    private int _beat = 4;

    private int _barSamples = 0;
    private int _beatSamples = 0;

    private const double OneMinute = 60.0;
    
    private const int LabelWidth = 130;

    [MenuItem("Tools/CalcSampleWindow")]
    static void Init()
    {
        var window = (CalcSampleWindow)EditorWindow.GetWindow(t:typeof(CalcSampleWindow), utility:false, title:"CalcSampleWindow");
        window.CalcSamples();
        window.Show();
    }


    void OnGUI()
    {
        EditorGUILayout.BeginVertical();

        var popupIndex = UnityEditor.EditorGUILayout.Popup(
            label: new UnityEngine.GUIContent("サンプリングレート"),
            selectedIndex: _popupIndex,
            displayedOptions: _popupDisplayOptions
        );
        if (_popupIndex != popupIndex)
        {
            _popupIndex = popupIndex;
            CalcSamples();
        }

        EditorGUILayout.BeginHorizontal();
        {
            GUILayout.Label("BPM",GUILayout.Width(LabelWidth));
            _bpmString = GUILayout.TextField(_bpmString);
            if(int.TryParse(_bpmString, out var bpm))
            {
                if(_bpm != bpm)
                {
                    _bpm = bpm;
                    CalcSamples();
                }
            }
        }
        EditorGUILayout.EndHorizontal();
        
        EditorGUILayout.BeginHorizontal();
        {
            GUILayout.Label("拍子(Beats)", GUILayout.Width(LabelWidth));
            _beatString = GUILayout.TextField(_beatString);
            if(int.TryParse(_beatString, out var beat))
            {
                if(_beat != beat)
                {
                    _beat = beat;
                    CalcSamples();
                }
            }
        }
        EditorGUILayout.EndHorizontal();

        EditorGUILayout.Space(8);
        
        EditorGUILayout.BeginHorizontal();
        {
            GUILayout.Label("1小節(Bar)", GUILayout.Width(LabelWidth));
            GUILayout.Label(_barSamples.ToString());
        }
        EditorGUILayout.EndHorizontal();
        
        EditorGUILayout.BeginHorizontal();
        {
            GUILayout.Label("4分音符(Beat)", GUILayout.Width(LabelWidth));
            GUILayout.Label(_beatSamples.ToString());
        }
        EditorGUILayout.EndHorizontal();

        EditorGUILayout.EndVertical();

    }

    private void CalcSamples()
    {
        var sampleRate = 44100;
        if (_popupIndex == 1)
        {
            sampleRate = 48000;
        }
        
        var barSeconds = OneMinute / _bpm * _beat;
        _barSamples = (int)(barSeconds * sampleRate);
        _beatSamples = _barSamples / _beat;
    }
}