[Unity] TakePhotoAsync only working once

Gwendal_Broudin

Hello,

I have a very strange behavior with the locatable camera API on Hololens.
When I trigger capture.TakePhotoAsync, the callback is only called once. On the second time I trigger it, the callback is never called and the opened thread never seems to be closed, it looks like TakePhotoAsync keeps on running. The debugger even failed to close :

However it is working perfectly in the editor.

Here is my code :

using System;
using System.Collections;
using System.Linq;
using HoloToolkit.Unity.InputModule;
using HoloToolkit.Unity;
using UnityEngine;
using UnityEngine.XR.WSA.WebCam;

/// <summary>
/// Manages taking and saving photos.
/// </summary>
public class PhotoManager : Singleton<PhotoManager>
{
    /// <summary>
    /// Actual camera instance.
    /// </summary>
    private PhotoCapture capture;

    /// <summary>
    /// True, if the camera is ready to take photos.
    /// </summary>
    public bool isReady { get; private set; }
    public Resolution resolution { get; private set; }

    #region EVENTS
    public event Action<bool> OnCaptureReady;
    public event Action OnCaptureOff;
    #endregion

    private Coroutine launchedStartCapture;
    private CameraParameters cameraParameters;

    protected override void Awake()
    {
        base.Awake();
        isReady = false;
        // This resolution guarantee that it will have holograms in the whole picture
        resolution = PhotoCapture.SupportedResolutions.OrderByDescending(res => res.width * res.height).ElementAt(1);
        cameraParameters = new CameraParameters(WebCamMode.PhotoMode)
        {
            hologramOpacity = 1.0f,
            cameraResolutionWidth = resolution.width,
            cameraResolutionHeight = resolution.height,
            pixelFormat = CapturePixelFormat.BGRA32
        };
    }

    private void OnDisable()
    {
        StopCapture();
    }

    public void StartCapture(Action<bool> callback = null)
    {
        if (launchedStartCapture != null)
        {
            StopCoroutine(launchedStartCapture);
        }

        launchedStartCapture = StartCoroutine(StartCaptureCoroutine(callback));
    }

    private IEnumerator StartCaptureCoroutine(Action<bool> callback = null)
    {
        bool stopped = false;
        StopCapture(res => stopped = true);

        yield return new WaitUntil(() => stopped);

        if (WebCam.Mode != WebCamMode.None)
        {
            Debug.LogErrorFormat(this, "Can't activate capture, webcam is already in mode {0}", WebCam.Mode);
            if (callback != null) callback(false);
            yield break;
        }

        if (ExakisTools.Utils.HoloLensHelpers.IsStreaming())
        {
            Debug.LogErrorFormat(this, "Can't activate capture, application is in currently streaming");
            if (callback != null) callback(false);
            yield break;
        }

        PhotoCapture.CreateAsync(true, captureObject =>
        {
            capture = captureObject;

            capture.StartPhotoModeAsync(cameraParameters, res => this.OnPhotoModeStarted(res, callback));
        });
    }

    private void OnPhotoModeStarted(PhotoCapture.PhotoCaptureResult result, Action<bool> callback)
    {
        isReady = result.success;
        if (OnCaptureReady != null) OnCaptureReady(isReady);
        if (isReady)
        {
            callback?.Invoke(true);
            // [Quick Fix] Hologramms are not shown on first picture
            // capture.TakePhotoAsync((photoResult, photoCaptureFrame) =>
            // {
            //     photoCaptureFrame.Dispose();
            //     photoCaptureFrame = null;
            //     callback?.Invoke(true);
            // });
            Debug.Log("Camera ready");
        }
        else
        {
            Debug.LogErrorFormat(this, "Failed to activate capture, if you are streaming, please remove it, reason : {0}", result.resultType);
        }
    }

    /// <summary>
    /// Take a picture if the capture is on
    /// </summary>
    /// <param name="photoTaken"> Callback when the picture is taken </param>
    public void TakePhoto(Action<Texture2D> photoTaken = null)
    {
        if (isReady)
        {
            UnityEngine.XR.WSA.HolographicSettings.SetFocusPointForFrame(CameraCache.Main.transform.TransformPoint(0, 0, 1f), -CameraCache.Main.transform.forward);
            capture.TakePhotoAsync((result, photoCaptureFrame) =>
            {
                if (result.success)
                {
                    Texture2D targetTexture = new Texture2D(resolution.width, resolution.height, TextureFormat.BGRA32, false);
                    photoCaptureFrame.UploadImageDataToTexture(targetTexture);
                    photoCaptureFrame.Dispose();
                    photoTaken.Invoke(targetTexture);
                }
                else
                {
                    Debug.LogErrorFormat("Failed to take photo {0}", result.hResult);
                }
            });
        }
        else
        {
            Debug.LogWarning("The camera is not yet ready.");
        }
    }

    /// <summary>
    /// Stop the photo mode.
    /// </summary>
    /// <param name="callback"> return true if the capture has been stopped</param>
    public void StopCapture(Action<bool> callback = null)
    {
        if (capture != null)
        {
            capture.StopPhotoModeAsync(result =>
            {
                capture.Dispose();
                capture = null;
                isReady = false;
                Debug.Log("Camera off");
                if (OnCaptureOff != null) OnCaptureOff();
                if (callback != null) callback(true);
            });
        }
        else
        {
            if (callback != null) callback(false);
        }
    }
}

I am aware there are a lot of problems with photo capture on HoloLens by now but I didn't found anything about this behavior at the moment.

If we have to wait to have it fixed, is there a workaround ? Like using the UWP API maybe ?

Here is my configuration:
Unity 2017.4.11f1 LTS
Scripting runtime : .NET 4.6
Windows SDK: 10.0.17134.0
Hololens OS: RS4 update