SampleQRReader.cs

using Cysharp.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;

public class SampleQRReader : MonoBehaviour
{
    private string _result = "";
    private WebCamTexture _webCam;

    void Awake()
    {
        ReadyWebCamAsync().Forget();
    }

    void Update()
    {
        if (_webCam != null && QRCodeHelper.TryRead(_webCam, out var result))
        {
            _result = result;
        }
        else
        {
            _result = "ERROR";
        }

        CheckDebugMode();
    }

    private async UniTask ReadyWebCamAsync()
    {
        await Application.RequestUserAuthorization(UserAuthorization.WebCam);

        if (Application.HasUserAuthorization(UserAuthorization.WebCam) == false)
        {
            return;
        }

        WebCamDevice[] devices = WebCamTexture.devices;

        if (devices == null || devices.Length == 0)
        {
            return;
        }

        _webCam = new WebCamTexture(devices[0].name, Screen.width, Screen.height, 12);
        _webCam.Play();
    }

    void OnGUI()
    {
        _isDebug = GUILayout.Toggle(_isDebug, "DEBUGモード", GUILayout.Height(100f), GUILayout.Width(100f));
        GUILayout.Label(_result, GUILayout.Width(300f), GUILayout.Height(200f));
    }

    #region Debug

    private bool _isDebug = true;
    private bool _isDebugMode;
    private GameObject _debugView;
    
    void CheckDebugMode()
    {
        if (_isDebugMode != _isDebug)
        {
            _isDebugMode = _isDebug;
            if (_isDebugMode)
                ShowDebugView();
            else
                HideDebugView();
        }
    }

    /// <summary>
    /// 画面右上にWebCamを表示させる
    /// </summary>
    void ShowDebugView()
    {
        if (_debugView != null) return;

        _debugView = new GameObject("DebugQR");
        var debugRawObj = new GameObject("Raw");
        debugRawObj.transform.SetParent(_debugView.transform, false);
        var rawImage = debugRawObj.AddComponent<RawImage>();
        var c = _debugView.AddComponent<Canvas>();
        c.renderMode = RenderMode.ScreenSpaceOverlay;
        rawImage.texture = _webCam;
        float w = 200f;
        float h = w * Screen.width / Screen.height;
        rawImage.rectTransform.sizeDelta = new Vector2(w, h);
        rawImage.rectTransform.anchorMax = new Vector2(1f, 1f);
        rawImage.rectTransform.anchorMin = new Vector2(1f, 1f);
        rawImage.rectTransform.anchoredPosition = new Vector2(-w * 0.5f, -h * 0.5f);
    }

    void HideDebugView()
    {
        Destroy(_debugView);
        _debugView = null;
    }

    #endregion
}