kotlin - 如何在CameraX上的相机预览中裁剪图像矩形

Question

我有一个自定义的相机应用，该应用具有居中的矩形 View ，如下所示:



拍照时，我想忽略矩形外的所有内容。这是我的XML布局:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/black_50">

    <TextureView
        android:id="@+id/viewFinder"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:layout_margin="16dp"
        android:background="@drawable/rectangle"
        app:layout_constraintBottom_toTopOf="@+id/cameraBottomView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/cameraBottomView"
        android:layout_width="match_parent"
        android:layout_height="130dp"
        android:background="@color/black_50"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <ImageButton
        android:id="@+id/cameraCaptureImageButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@android:color/transparent"
        android:src="@drawable/ic_capture_image"
        app:layout_constraintBottom_toBottomOf="@id/cameraBottomView"
        app:layout_constraintEnd_toEndOf="@id/cameraBottomView"
        app:layout_constraintStart_toStartOf="@id/cameraBottomView"
        app:layout_constraintTop_toTopOf="@id/cameraBottomView"
        tools:ignore="ContentDescription" />

</androidx.constraintlayout.widget.ConstraintLayout>

这是我的cameraX预览的kotlin代码:

class CameraFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_camera, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        viewFinder.post { setupCamera() }
    }

    private fun setupCamera() {
        CameraX.unbindAll()
        CameraX.bindToLifecycle(
            this,
            buildPreviewUseCase(),
            buildImageCaptureUseCase(),
            buildImageAnalysisUseCase()
        )
    }

    private fun buildPreviewUseCase(): Preview {
        val preview = Preview(
            UseCaseConfigBuilder.buildPreviewConfig(
                viewFinder.display
            )
        )
        preview.setOnPreviewOutputUpdateListener { previewOutput ->
            updateViewFinderWithPreview(previewOutput)
            correctPreviewOutputForDisplay(previewOutput.textureSize)
        }
        return preview
    }

    private fun updateViewFinderWithPreview(previewOutput: Preview.PreviewOutput) {
        val parent = viewFinder.parent as ViewGroup
        parent.removeView(viewFinder)
        parent.addView(viewFinder, 0)
        viewFinder.surfaceTexture = previewOutput.surfaceTexture
    }

    /**
     * Corrects the camera/preview's output to the display, by scaling
     * up/down and/or rotating the camera/preview's output.
     */
    private fun correctPreviewOutputForDisplay(textureSize: Size) {
        val matrix = Matrix()

        val centerX = viewFinder.width / 2f
        val centerY = viewFinder.height / 2f

        val displayRotation = getDisplayRotation()
        val (dx, dy) = getDisplayScalingFactors(textureSize)

        matrix.postRotate(displayRotation, centerX, centerY)
        matrix.preScale(dx, dy, centerX, centerY)

        // Correct preview output to account for display rotation and scaling
        viewFinder.setTransform(matrix)
    }

    private fun getDisplayRotation(): Float {
        val rotationDegrees = when (viewFinder.display.rotation) {
            Surface.ROTATION_0 -> 0
            Surface.ROTATION_90 -> 90
            Surface.ROTATION_180 -> 180
            Surface.ROTATION_270 -> 270
            else -> throw IllegalStateException("Unknown display rotation ${viewFinder.display.rotation}")
        }
        return -rotationDegrees.toFloat()
    }

    private fun getDisplayScalingFactors(textureSize: Size): Pair<Float, Float> {
        val cameraPreviewRation = textureSize.height / textureSize.width.toFloat()
        val scaledWidth: Int
        val scaledHeight: Int
        if (viewFinder.width > viewFinder.height) {
            scaledHeight = viewFinder.width
            scaledWidth = (viewFinder.width * cameraPreviewRation).toInt()
        } else {
            scaledHeight = viewFinder.height
            scaledWidth = (viewFinder.height * cameraPreviewRation).toInt()
        }
        val dx = scaledWidth / viewFinder.width.toFloat()
        val dy = scaledHeight / viewFinder.height.toFloat()
        return Pair(dx, dy)
    }

    private fun buildImageCaptureUseCase(): ImageCapture {
        val capture = ImageCapture(
            UseCaseConfigBuilder.buildImageCaptureConfig(
                viewFinder.display
            )
        )
        cameraCaptureImageButton.setOnClickListener {
            capture.takePicture(
                FileCreator.createTempFile(JPEG_FORMAT),
                Executors.newSingleThreadExecutor(),
                object : ImageCapture.OnImageSavedListener {
                    override fun onImageSaved(file: File) {
                        requireActivity().runOnUiThread {
                            launchGalleryFragment(file.absolutePath)
                        }
                    }

                    override fun onError(
                        imageCaptureError: ImageCapture.ImageCaptureError,
                        message: String,
                        cause: Throwable?
                    ) {
                        Toast.makeText(requireContext(), "Error: $message", Toast.LENGTH_LONG)
                            .show()
                        Log.e("CameraFragment", "Capture error $imageCaptureError: $message", cause)
                    }
                })
        }
        return capture
    }

    private fun buildImageAnalysisUseCase(): ImageAnalysis {
        val analysis = ImageAnalysis(
            UseCaseConfigBuilder.buildImageAnalysisConfig(
                viewFinder.display
            )
        )
        analysis.setAnalyzer(
            Executors.newSingleThreadExecutor(),
            ImageAnalysis.Analyzer { image, rotationDegrees ->
                Log.d(
                    "CameraFragment",
                    "Image analysis: $image - Rotation degrees: $rotationDegrees"
                )
            })
        return analysis
    }

    private fun launchGalleryFragment(path: String) {
        val action = CameraFragmentDirections.actionLaunchGalleryFragment(path)
        findNavController().navigate(action)
    }

}

当我拍摄照片并将其发送到新页面(GalleryPage)时，它将显示相机预览中的所有屏幕，如下所示:



这是kotlin代码，用于从cameraX预览中获取图片并将其显示到ImageView中:

class GalleryFragment : Fragment() {

    private lateinit var imageView: ImageView


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_gallery, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        imageView = view.findViewById(R.id.img)

        val imageFilePath = GalleryFragmentArgs.fromBundle(arguments!!).data
        val bitmap = BitmapFactory.decodeFile(imageFilePath)
        val rotatedBitmap = bitmap.rotate(90)

        if (imageFilePath.isBlank()) {
            Log.i(
                "GalleryFragment",
                "Image is Null or Empty"
            )
        } else {
            Glide.with(activity!!)
                .load(rotatedBitmap)
                .into(imageView)
        }

    }

    private fun Bitmap.rotate(degree:Int):Bitmap{
        // Initialize a new matrix
        val matrix = Matrix()

        // Rotate the bitmap
        matrix.postRotate(degree.toFloat())

        // Resize the bitmap
        val scaledBitmap = Bitmap.createScaledBitmap(
            this,
            width,
            height,
            true
        )

        // Create and return the rotated bitmap
        return Bitmap.createBitmap(
            scaledBitmap,
            0,
            0,
            scaledBitmap.width,
            scaledBitmap.height,
            matrix,
            true
        )
    }

}

有人可以帮助我如何正确裁剪图像吗？因为我已经搜索并研究了如何做，但仍然感到困惑，对我不起作用。

Answer 1

正如您所提到的，这是我如何裁剪由cameraX拍摄的图像的示例。我不知道这是否是最好的方法，我很想知道其他解决方案。

camerax_version =“1.0.0-alpha07”

CameraFragment.java

初始化cameraX:

// Views
private PreviewView previewView;
// CameraX
private ProcessCameraProvider cameraProvider;
private ListenableFuture<ProcessCameraProvider> cameraProviderFuture;
private CameraSelector cameraSelector;
private Executor executor;
private ImageCapture imageCapture;

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    cameraProviderFuture = ProcessCameraProvider.getInstance(getContext());
    executor = ContextCompat.getMainExecutor(getContext());
    cameraSelector = new CameraSelector.Builder().requireLensFacing(LensFacing.BACK).build();
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    previewView = view.findViewById(R.id.preview);
    ImageButton btnCapture = view.findViewById(R.id.btn_capture);
    // Wait for the view to be properly laid out
    previewView.post(() ->{
        //Initialize CameraX
        cameraProviderFuture.addListener(() -> {
            if(cameraProvider != null) cameraProvider.unbindAll();
            try {
                cameraProvider = cameraProviderFuture.get();
                // Set up the preview use case to display camera preview
                Preview preview = new Preview.Builder()
                        .setTargetAspectRatio(AspectRatio.RATIO_4_3)
                        .setTargetRotation(previewView.getDisplay().getRotation())
                        .build();

                preview.setPreviewSurfaceProvider(previewView.getPreviewSurfaceProvider());

                // Set up the capture use case to allow users to take photos
                imageCapture = new ImageCapture.Builder()
                        .setCaptureMode(ImageCapture.CaptureMode.MINIMIZE_LATENCY)
                        .setTargetRotation(previewView.getDisplay().getRotation())
                        .setTargetAspectRatio(AspectRatio.RATIO_4_3)
                        .build();

                // Apply declared configs to CameraX using the same lifecycle owner
                cameraProvider.bindToLifecycle(this, cameraSelector, preview,imageCapture);
            } catch (ExecutionException | InterruptedException e) {
                e.printStackTrace();
            }
        }, ContextCompat.getMainExecutor(getContext()));
    });

    btnCapture.setOnClickListener(v -> {
        String format = "yyyy-MM-dd-HH-mm-ss-SSS";
        SimpleDateFormat fmt = new SimpleDateFormat(format, Locale.US);
        String date = fmt.format(System.currentTimeMillis());

        File file = new File(getContext().getCacheDir(), date+".jpg");
        imageCapture.takePicture(file, executor, imageSavedListener);
    });
}

拍摄完照片后，打开通过照片路径的画廊片段:

private ImageCapture.OnImageSavedCallback imageSavedListener = new ImageCapture.OnImageSavedCallback() {
    @Override
    public void onImageSaved(@NonNull File photoFile) {
        // Create new fragment and transaction
        Fragment newFragment = new GalleryFragment();
        FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
        // Set arguments
        Bundle args = new Bundle();
        args.putString("KEY_PATH", Uri.fromFile(photoFile).toString());
        newFragment.setArguments(args);
        // Replace whatever is in the fragment_container view with this fragment,
        transaction.replace(R.id.fragment_container, newFragment,null);
        transaction.addToBackStack(null);
        // Commit the transaction
        transaction.commit();
    }

    @Override
    public void onError(int imageCaptureError, @NonNull String message, @Nullable Throwable cause) {
        if (cause != null) {
            cause.printStackTrace();
        }
    }
};

目前，照片尚未裁剪，我不知道是否可以直接用cameraX进行照片裁剪。

GalleryFragment.java

加载传递给片段的参数。

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    String path = getArguments().getString("KEY_PATH");
    sourceUri = Uri.parse(path);
}

在ImageView中向Uri加载滑行，然后对其进行裁剪。

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    // Initialize the views
    ImageView imageView = view.findViewById(R.id.image_view);
    View cropArea = view.findViewById(R.id.crop_area);
    // Display the image
    Glide.with(this).load(sourceUri).listener(new RequestListener<Drawable>() {
        @Override
        public boolean onLoadFailed(@Nullable GlideException e, Object model, Target<Drawable> target, boolean isFirstResource) {
            return false;
        }

        @Override
        public boolean onResourceReady(Drawable resource, Object model, Target<Drawable> target, DataSource dataSource, boolean isFirstResource) {
            // Get original bitmap
            sourceBitmap = ((BitmapDrawable)resource).getBitmap();

            // Create a new bitmap corresponding to the crop area
            int[] cropAreaXY = new int[2];
            int[] placeHolderXY = new int[2];
            Rect rect = new Rect();
            imageView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener(){
                @Override
                public boolean onPreDraw() {
                    try {
                        imageView.getLocationOnScreen(placeHolderXY);

                        cropArea.getLocationOnScreen(cropAreaXY);
                        cropArea.getGlobalVisibleRect(rect);

                        croppedBitmap = Bitmap.createBitmap(sourceBitmap, cropAreaXY[0], cropAreaXY[1] - placeHolderXY[1], rect.width(), rect.height());
                        // Save the croppedBitmap if you wish

                        getActivity().runOnUiThread(() -> imageView.setImageBitmap(croppedBitmap));
                        return true;
                    }finally {
                        imageView.getViewTreeObserver().removeOnPreDrawListener(this);
                    }
                }
            });
            return false;
        }
    }).into(imageView);
}

fragment_camera.xml

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black">

    <androidx.camera.view.PreviewView
        android:id="@+id/preview"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintDimensionRatio="3:4"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/crop_area"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="8dp"
        android:background="@drawable/rectangle_round_corners"
        app:layout_constraintBottom_toBottomOf="@+id/preview"
        app:layout_constraintDimensionRatio="4.5:3"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/cameraBottomView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@android:color/black"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/preview" />


    <ImageButton
        android:id="@+id/btn_capture"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:layout_marginTop="8dp"
        android:layout_marginBottom="8dp"
        android:background="@drawable/ic_shutter"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/preview" />
</androidx.constraintlayout.widget.ConstraintLayout>

fragment_gallery.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/layout_main"
    android:background="@android:color/black"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/image_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:visibility="visible"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/crop_area"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="4.5:3"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>