android - 使用 cameraX 的 PreviewView 捕获叠加层

Question

我正在尝试使用图像捕获中包含的叠加层来捕获图片。我能够将覆盖设置为 previewView使用 cameraView.overlay.add(binding.textView) .但是，当尝试使用 imageCapture 保存图像时，它没有保存。只有图片被保存而不是覆盖。如何使用 PreviewView 保存包含叠加层的图像相机 x。
请不要将此标记为重复。我研究了很多，大多数在线示例都使用旧的 camera不适用于相机 x 库的 api。任何帮助表示赞赏。提前致谢。
这是我的代码

           <FrameLayout
                android:id="@+id/camera_wrapper"
                android:layout_width="match_parent"
                android:layout_height="0dp"
                app:layout_constraintTop_toTopOf="@id/space1"
                app:layout_constraintBottom_toBottomOf="@id/space">
    
                <androidx.camera.view.PreviewView
                    android:id="@+id/camera_view"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />
    
                <TextView
                    android:id="@+id/text_view"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:text="Hello world"
                    android:textSize="42sp"
                    android:textColor="@android:color/holo_green_dark"/>
    
            </FrameLayout>

  private lateinit var outputDirectory: File
  private lateinit var cameraExecutor: ExecutorService
  private var preview: Preview? = null
  private var lensFacing: Int = CameraSelector.LENS_FACING_FRONT
  private var imageCapture: ImageCapture? = null
  private var camera: Camera? = null
  private var cameraProvider: ProcessCameraProvider? = null

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    outputDirectory = getOutputDirectory()
    cameraExecutor = Executors.newSingleThreadExecutor()
  }

  private fun setupCamera() {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(requireContext())

    cameraProviderFuture.addListener(
      Runnable {
        // Used to bind the lifecycle of cameras to the lifecycle owner
        cameraProvider = cameraProviderFuture.get()

        // Get screen metrics used to setup camera for full screen resolution
        val metrics = DisplayMetrics().also { binding.cameraView.display.getRealMetrics(it) }
        Timber.d("Screen metrics: ${metrics.widthPixels} x ${metrics.heightPixels}")

        val screenAspectRatio = aspectRatio(metrics.widthPixels, metrics.heightPixels)
        Timber.d("Preview aspect ratio: $screenAspectRatio")

        val rotation = binding.cameraView.display.rotation

        // CameraProvider
        val cameraProvider = cameraProvider
          ?: throw IllegalStateException("Camera initialization failed.")

        // CameraSelector
        val cameraSelector = CameraSelector.Builder().requireLensFacing(lensFacing).build()

        // add text overlay *---------*
        binding.cameraView.overlay.add(binding.textView)

        // Preview
        preview = Preview.Builder()
          // We request aspect ratio but no resolution
          .setTargetAspectRatio(screenAspectRatio)
          // Set initial target rotation
          .setTargetRotation(rotation)
          .build()

        // ImageCapture
        imageCapture = ImageCapture.Builder()
          .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
          // We request aspect ratio but no resolution to match preview config, but letting
          // CameraX optimize for whatever specific resolution best fits our use cases
          .setTargetAspectRatio(screenAspectRatio)
          // Set initial target rotation, we will have to call this again if rotation changes
          // during the lifecycle of this use case
          .setTargetRotation(rotation)
          .build()

        // Must unbind the use-cases before rebinding them
        cameraProvider.unbindAll()

        try {
          // A variable number of use-cases can be passed here -
          // camera provides access to CameraControl & CameraInfo
          camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview, imageCapture)
          // Attach the viewfinder's surface provider to preview use case
          preview?.setSurfaceProvider(binding.cameraView.surfaceProvider)
        } catch (exc: Exception) {
          Toast.makeText(requireContext(), "Something went wrong. Please try again.", Toast.LENGTH_SHORT).show()
          findNavController().navigateUp()
        }
      },
      ContextCompat.getMainExecutor(requireContext())
    )
  }

private fun takePhoto() {
    imageCapture?.let { imageCapture ->

      // Create output file to hold the image
      val photoFile = createFile(outputDirectory, FILENAME, PHOTO_EXTENSION)

      // Setup image capture metadata
      val metadata = ImageCapture.Metadata().apply {

        // Mirror image when using the front camera
        isReversedHorizontal = lensFacing == CameraSelector.LENS_FACING_FRONT
      }

      // Create output options object which contains file + metadata
      val outputOptions = ImageCapture.OutputFileOptions.Builder(photoFile)
          .setMetadata(metadata)
          .build()

      // Setup image capture listener which is triggered after photo has been taken
      imageCapture.takePicture(outputOptions, cameraExecutor, object : ImageCapture.OnImageSavedCallback {
        override fun onError(exc: ImageCaptureException) {
          Timber.e(exc, "Photo capture failed: ${exc.message}")
        }

        override fun onImageSaved(output: ImageCapture.OutputFileResults) {
          val savedUri = output.savedUri ?: Uri.fromFile(photoFile)
          Timber.d("Photo capture succeeded: $savedUri")

          // Implicit broadcasts will be ignored for devices running API level >= 24
          // so if you only target API level 24+ you can remove this statement
          if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
            requireActivity()
                .sendBroadcast(Intent(android.hardware.Camera.ACTION_NEW_PICTURE, savedUri))
          }


          // If the folder selected is an external media directory, this is
          // unnecessary but otherwise other apps will not be able to access our
          // images unless we scan them using [MediaScannerConnection]
          val mimeType = MimeTypeMap.getSingleton()
              .getMimeTypeFromExtension(savedUri.toFile().extension)
          MediaScannerConnection.scanFile(
              context,
              arrayOf(savedUri.toFile().absolutePath),
              arrayOf(mimeType)
          ) { _, uri ->
            Timber.d("Image capture scanned into media store: $uri")
          }
        }
      })
    }

  }

Answer 1

您必须自己将文本覆盖在图像上。我建议使用 takePicture(Executor, …)将 Jpeg 放入内存中；然后，使用其中一个库(不是 Android 框架的一部分，也不是 Jetpack 的一部分)覆盖您的文本，并将结果保存在文件中。
如果您可以在图像质量上妥协，您可以在位图 Canvas 上绘制 Jpeg，然后在顶部绘制文本。