Question

我试图将拍摄的照片保存到HoloLens上的磁盘上。尝试根据this example在Unity中保存照片时，我收到以下异常错误。有一段时间我无法获得正确的目录来保存文件，现在我想我终于让那部分工作了（参见下面的getFolderPath函数）。但是，现在我得到了下面引用的这个例外。关于如何解决这个问题的任何想法？

我正在使用Origami示例代码，我只是将此脚本PhotoCaptureTest.cs附加到Unity中的OrigamiCollection游戏对象。有谁知道如何解决这个问题或者我如何更容易地调试它？

抛出异常：＆＃39; System.NullReferenceException＆＃39;在UnityEngine.dll中 NullReferenceException：对象引用未设置为的实例宾语。在 UnityEngine.VR.WSA.WebCam.PhotoCapture.InvokeOnCapturedPhotoToDiskDelegate（OnCapturedToDiskCallback 回调，Int64 hResult）at UnityEngine.VR.WSA.WebCam.PhotoCapture。$ Invoke9（Int64实例，Int64 * args）在UnityEngine.Internal。$ MethodUtility.InvokeMethod（Int64 实例，Int64 * args，IntPtr方法）（文件名：行：0）

using UnityEngine;
using System.Collections;
using UnityEngine.VR.WSA.WebCam;
using System.Linq;
using Windows.Storage;
using System;
using System.IO;

public class PhotoCaptureTest : MonoBehaviour {

    PhotoCapture photoCaptureObject = null;
    string folderPath = "";
    bool haveFolderPath = false;

    // Use this for initialization
    void Start ()
    {
        getFolderPath();
        while (!haveFolderPath)
        {
            Debug.Log("Waiting for folder path...");
        }
        Debug.Log("About to call CreateAsync");
        PhotoCapture.CreateAsync(false, OnPhotoCaptureCreated);
        Debug.Log("Called CreateAsync");
    }

    // Update is called once per frame
    void Update () {

    }

    async void getFolderPath()
    {
        StorageLibrary myPictures = await Windows.Storage.StorageLibrary.GetLibraryAsync(Windows.Storage.KnownLibraryId.Pictures);
        Windows.Storage.StorageFolder savePicturesFolder = myPictures.SaveFolder;
        Debug.Log("savePicturesFolder.Path is " + savePicturesFolder.Path);
        folderPath = savePicturesFolder.Path;
        haveFolderPath = true;
    }

    void OnPhotoCaptureCreated(PhotoCapture captureObject)
    {
        photoCaptureObject = captureObject;

        Resolution cameraResolution = PhotoCapture.SupportedResolutions.OrderByDescending((res) => res.width * res.height).First();

        CameraParameters c = new CameraParameters();
        c.hologramOpacity = 0.0f;
        c.cameraResolutionWidth = cameraResolution.width;
        c.cameraResolutionHeight = cameraResolution.height;
        c.pixelFormat = CapturePixelFormat.BGRA32;

        captureObject.StartPhotoModeAsync(c, false, OnPhotoModeStarted);
    }

    void OnStoppedPhotoMode(PhotoCapture.PhotoCaptureResult result)
    {
        photoCaptureObject.Dispose();
        photoCaptureObject = null;
    }

    private void OnPhotoModeStarted(PhotoCapture.PhotoCaptureResult result)
    {
        if (result.success)
        {
            string filename = string.Format(@"\CapturedImage{0}_n.jpg", Time.time);
            string filePath = folderPath + filename;
            string currentDir = Directory.GetCurrentDirectory();
            Debug.Log("Current working direcotry is " + currentDir);
            Debug.Log("Saving photo to " + filePath);

            try
            {
                photoCaptureObject.TakePhotoAsync(filePath, PhotoCaptureFileOutputFormat.JPG, OnCapturedPhotoToDisk);
            }
            catch (System.ArgumentException e)
            {
                Debug.LogError("System.ArgumentException:\n" + e.Message);
            }
        }
        else
        {
            Debug.LogError("Unable to start photo mode!");
        }
    }

    void OnCapturedPhotoToDisk(PhotoCapture.PhotoCaptureResult result)
    {
        if (result.success)
        {
            Debug.Log("Saved Photo to disk!");
            photoCaptureObject.StopPhotoModeAsync(OnStoppedPhotoMode);
        }
        else
        {
            Debug.Log("Failed to save Photo to disk");
        }
    }
}

Answer 1

确保在保存文件之前将Visual Studio附加到unity并设置断点，并检查引用。我怀疑它即将到来null，同时确保在您的manifest中启用 WebCam +照片支持，这可能会导致null。

Answer 2

我发现捕获和保存照片的代码应该是正确的，我遇到了和你一样的错误。

为避免错误，我可以通过将目录更改为Application.persistentDataPath来保存照片，即将Start()修改为以下

// ...
void Start()
{
    folderPath = Application.persistentDataPath;
    PhotoCapture.CreateAsync(false, OnPhotoCaptureCreated);
}
// ...

然后可以通过路径UserFiles\LocalAppData\<APPNAME>\LocalState\获取照片，该路径可以通过Hololens Device Portal的文件资源管理器找到。

HoloLens - 在Unity中捕获照片并保存到磁盘

2 个答案: