registerForActivityResult(ActivityResultContracts.TakeVideo())总是空的。

Question

我使用以下代码捕获视频。一切都很好，但是在捕获视频之后，registerForActivityResult(ActivityResultContracts.TakeVideo())总是为空。捕获的视频存在于给定的路径中。我能用什么方法解决这个问题？

 private fun openCameraForMovie() {
        val packageManager = requireContext().packageManager
        Intent(MediaStore.ACTION_VIDEO_CAPTURE).also { takeVideoIntent ->
            takeVideoIntent.resolveActivity(packageManager)?.also {
                startRecording()
            }
        }
    }




 private fun startRecording() {
        try {
            val root = File(
                requireContext().getExternalFilesDir(Environment.DIRECTORY_PICTURES)
                    .toString() + "/media/"
            )

            if (!root.exists()) {
                root.mkdir()
            }

            val videoName = "vid_" + System.currentTimeMillis() + ".mp4"
            val sdImageMainDirectory = File(root, videoName)

            var fileUri: Uri? = FileProvider.getUriForFile(
                requireContext(),
                context?.applicationContext?.packageName + ".provider",
                sdImageMainDirectory
            ) ?: return

        
            mViewModel.videoUri.postValue(fileUri)

        } catch (ex: Exception) {
            Timber.d("startRecording ${ex.localizedMessage}")
        }
    }

此代码始终为空：

  private val recordVideoResult =
        registerForActivityResult(ActivityResultContracts.TakeVideo()) { it ->
            try {
                if (it != null) {
                    Timber.d(">>>> Video Bitmap: $it") 
                }
            } catch (ex: Exception) {
                Timber.d(">>>> Video Bitmap: ${ex.localizedMessage}")
            }
        }

Answer 1

发生什么事了呢？

保存到提供的content-**Uri.中的视频的ActivityResultContract 返回一个缩略图。**

源TakeVideo文档，强调地雷。

您不需要缩略图(反正这是可选的)，您需要指向实际视频的Uri。但是您已经知道了Uri，因为您提供了它作为输入。

这次又是什么？

要做到这一点，需要采取几个步骤：

1. 将输入的Uri存储在变量中，并正确处理保存状态，这样应用程序就知道当您从相机应用程序返回时，您一直在录制视频。
2. 编写自定义TakeVideo协议，如果视频捕获成功，它将返回。检查非空预览Bitmap无法使用，因为预览是可选的.

它看起来可能是这样的：

private AtomicReference<Uri> recordingUri = new AtomicReference<>();

private ActivityResultLauncher<Uri> recordVideoResult =
        registerForActivityResult(new TakeVideo2(), success -> {
            final Uri uri = recordingUri.getAndSet(null);
            if (success) {
                // Do something with the video.
            }
        });

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    // ...
    if (savedInstanceState != null) {
        recordingUri.set(savedInstanceState.getParcelable("recordingUri"));
    }
}

@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
    // ...
    outState.putParcelable("recordingUri", recordingUri.get());
}

private void startRecording() {
    final Uri uri = // ...;
    recordingUri.set(uri);
    recordVideoResult.launch(uri);
}

public static class TakeVideo2 extends ActivityResultContract<Uri, Boolean> {

    @CallSuper
    @NonNull
    @Override
    public Intent createIntent(@NonNull Context context, @NonNull Uri input) {
        return new Intent(MediaStore.ACTION_VIDEO_CAPTURE)
                .putExtra(MediaStore.EXTRA_OUTPUT, input);
    }

    @Nullable
    @Override
    public final SynchronousResult<Boolean> getSynchronousResult(@NonNull Context context,
            @NonNull Uri input) {
        return null;
    }

    @Override
    public final Boolean parseResult(int resultCode, @Nullable Intent intent) {
        return resultCode == Activity.RESULT_OK;
    }
}