Я создаю пользовательское приложение камеры. Проблема, с которой я сталкиваюсь, заключается в том, что предварительный просмотр камеры зависает, когда я переключаюсь между передней и задней камерой. При запуске упражнения с передней или задней камеры по телефону

boolean opened = safeCameraOpenInView(view, Camera.CameraInfo.CAMERA_FACING_BACK)

в методе OnCreateView фрагмента обе камеры будут отображаться при запуске, как и ожидалось. Как только я вызываю тот же метод в прослушивателе по нажатию кнопки переключения, камера сразу же зависает.

Это новая реализация, которую я попробовал, когда весь код находится внутри одного фрагмента вместо пользовательского класса, основываясь на следующем вопросе:Предварительный просмотр камеры пользовательского класса зависает при переключении камеры но результат точно такой же. Я почти уверен, что мне нужно что-то сделать с видом поверхности, чтобы связать это с новой камерой, но я не знаю, как это сделать. У кого-нибудь есть указатели?

Моя деятельность:

public class Camera2ActivityFragment extends Fragment {

    // Native camera.
    private Camera mCamera;


    // View to display the camera output.
    private CameraPreview mPreview;

    // Reference to the containing view.
    private View mCameraView;

    /**
     * Default empty constructor.
     */
    public Camera2ActivityFragment(){
        super();
    }

    /**
     * Static factory method
     * @param sectionNumber
     * @return
     */
    public static Camera2ActivityFragment newInstance(int sectionNumber) {
        Camera2ActivityFragment fragment = new Camera2ActivityFragment();
        //Bundle args = new Bundle();
        //args.putInt(ARG_SECTION_NUMBER, sectionNumber);
        //fragment.setArguments(args);
        return fragment;
    }

    /**
     * OnCreateView fragment override
     * @param inflater
     * @param container
     * @param savedInstanceState
     * @return
     */
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_camera2, container, false);
        boolean opened = safeCameraOpenInView(view, Camera.CameraInfo.CAMERA_FACING_BACK);

        if(opened == false){
            Log.d("CameraGuide","Error, Camera failed to open");
            return view;
        }

        // Trap the capture button.
        Button captureButton = (Button) view.findViewById(R.id.btnCameraStart);
        captureButton.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        // get an image from the camera
                        mCamera.takePicture(null, null, mPicture);
                    }
                }
        );

        Button switchCameraButton = (Button) view.findViewById(R.id.btnSwitchCamera);
        switchCameraButton.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        safeCameraOpenInView(getView(), Camera.CameraInfo.CAMERA_FACING_FRONT); //ISSUE OCCURS HERE!
                    }
                }
        );

        return view;
    }

    /**
     * Recommended "safe" way to open the camera.
     * @param view
     * @return
     */
    private boolean safeCameraOpenInView(View view, int camID) {
        boolean qOpened = false;
        releaseCameraAndPreview();
        //mCamera = getCameraInstance(Camera.CameraInfo.CAMERA_FACING_BACK);
        mCamera = getCameraInstance(camID);
        mCameraView = view;
        qOpened = (mCamera != null);

        if(qOpened == true){
            mPreview = new CameraPreview(getActivity().getBaseContext(), mCamera,view);
            FrameLayout preview = (FrameLayout) view.findViewById(R.id.camera_view);
            preview.addView(mPreview);
            mPreview.startCameraPreview();
        }
        return qOpened;
    }

    /**
     * Safe method for getting a camera instance.
     * @return
     */
    public static Camera getCameraInstance(int camID){
        Camera c = null;
        try {
            c = Camera.open(camID); // attempt to get a Camera instance
        }
        catch (Exception e){
            e.printStackTrace();
        }
        return c; // returns null if camera is unavailable
    }

    @Override
    public void onPause() {
        super.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        releaseCameraAndPreview();
    }

    /**
     * Clear any existing preview / camera.
     */
    private void releaseCameraAndPreview() {

        if (mCamera != null) {
            mCamera.stopPreview();
            mCamera.release();
            mCamera = null;
        }
        if(mPreview != null){
            mPreview.destroyDrawingCache();
            mPreview.mCamera = null;
        }
    }

    /**
     * Surface on which the camera projects it's capture results. This is derived both from Google's docs and the
     * excellent StackOverflow answer provided below.
     *
     * Reference / Credit: https://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
     */
    class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {

        // SurfaceHolder
        private SurfaceHolder mHolder;

        // Our Camera.
        private Camera mCamera;

        // Parent Context.
        private Context mContext;

        // Camera Sizing (For rotation, orientation changes)
        private Camera.Size mPreviewSize;

        // List of supported preview sizes
        private List<Camera.Size> mSupportedPreviewSizes;

        // Flash modes supported by this camera
        private List<String> mSupportedFlashModes;

        // View holding this camera.
        private View mCameraView;

        public CameraPreview(Context context, Camera camera, View cameraView) {
            super(context);

            // Capture the context
            mCameraView = cameraView;
            mContext = context;
            setCamera(camera);

            // Install a SurfaceHolder.Callback so we get notified when the
            // underlying surface is created and destroyed.
            mHolder = getHolder();
            mHolder.addCallback(this);
            mHolder.setKeepScreenOn(true);
            // deprecated setting, but required on Android versions prior to 3.0
            mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        }

        /**
         * Begin the preview of the camera input.
         */
        public void startCameraPreview()
        {
            try{
                mCamera.setPreviewDisplay(mHolder);
                mCamera.startPreview();
            }
            catch(Exception e){
                e.printStackTrace();
            }
        }

        /**
         * Extract supported preview and flash modes from the camera.
         * @param camera
         */
        private void setCamera(Camera camera)
        {
            // Source: https://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
            mCamera = camera;
            mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
            mSupportedFlashModes = mCamera.getParameters().getSupportedFlashModes();

            // Set the camera to Auto Flash mode.
            if (mSupportedFlashModes != null && mSupportedFlashModes.contains(Camera.Parameters.FLASH_MODE_AUTO)){
                Camera.Parameters parameters = mCamera.getParameters();
                parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
                parameters.setRotation(90);
                //parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
                mCamera.setParameters(parameters);
                mCamera.setDisplayOrientation(90);
            }

            requestLayout();
        }

        /**
         * The Surface has been created, now tell the camera where to draw the preview.
         * @param holder
         */
        public void surfaceCreated(SurfaceHolder holder) {
            try {
                mCamera.setPreviewDisplay(holder);

                //mCam = Camera.open();
                //mCam.setPreviewDisplay(holder);

            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        /**
         * Dispose of the camera preview.
         * @param holder
         */
        public void surfaceDestroyed(SurfaceHolder holder) {
            if (mCamera != null){
                mCamera.stopPreview();
            }
        }

        /**
         * React to surface changed events
         * @param holder
         * @param format
         * @param w
         * @param h
         */
        public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {

            //Log.e(TAG, "surfaceChanged => w=" + w + ", h=" + h);
            // If your preview can change or rotate, take care of those events here.
            // Make sure to stop the preview before resizing or reformatting it.
            if (mHolder.getSurface() == null){
                // preview surface does not exist
                return;
            }

            // stop preview before making changes
            try {
                mCamera.stopPreview();
                //mCamera.release();
            } catch (Exception e){
                // ignore: tried to stop a non-existent preview
            }

            // set preview size and make any resize, rotate or reformatting changes here
            // start preview with new settings
            try {
                Camera.Parameters parameters = mCamera.getParameters();
                parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
                parameters.setRotation(90);
                parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
                mCamera.setParameters(parameters);
                mCamera.setDisplayOrientation(90);
                mCamera.setPreviewDisplay(mHolder);
                mCamera.enableShutterSound(true);
                mCamera.startPreview();

            } catch (Exception e){
                //Log.d(TAG, "Error starting camera preview: " + e.getMessage());
            }
        }

        /**
         * Calculate the measurements of the layout
         * @param widthMeasureSpec
         * @param heightMeasureSpec
         */
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
        {
            /*
            // Source: https://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
            final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
            final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
            setMeasuredDimension(width, height);

            if (mSupportedPreviewSizes != null){
                mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
            }
            */
            final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
            final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);

            if (mSupportedPreviewSizes != null) {
                mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
            }

            float ratio;
            if(mPreviewSize.height >= mPreviewSize.width)
                ratio = (float) mPreviewSize.height / (float) mPreviewSize.width;
            else
                ratio = (float) mPreviewSize.width / (float) mPreviewSize.height;

            // One of these methods should be used, second method squishes preview slightly
            setMeasuredDimension(width, (int) (width * ratio));
//        setMeasuredDimension((int) (width * ratio), height);
        }

        /**
         * Update the layout based on rotation and orientation changes.
         * @param changed
         * @param left
         * @param top
         * @param right
         * @param bottom
         */
        @Override
        protected void onLayout(boolean changed, int left, int top, int right, int bottom)
        {
            // Source: https://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
            if (changed) {
                final int width = right - left;
                final int height = bottom - top;

                int previewWidth = width;
                int previewHeight = height;

                if (mPreviewSize != null){
                    Display display = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();

                    switch (display.getRotation())
                    {
                        case Surface.ROTATION_0:
                            previewWidth = mPreviewSize.height;
                            previewHeight = mPreviewSize.width;
                            mCamera.setDisplayOrientation(90);
                            break;
                        case Surface.ROTATION_90:
                            previewWidth = mPreviewSize.width;
                            previewHeight = mPreviewSize.height;
                            break;
                        case Surface.ROTATION_180:
                            previewWidth = mPreviewSize.height;
                            previewHeight = mPreviewSize.width;
                            break;
                        case Surface.ROTATION_270:
                            previewWidth = mPreviewSize.width;
                            previewHeight = mPreviewSize.height;
                            mCamera.setDisplayOrientation(180);
                            break;
                    }
                }

                final int scaledChildHeight = previewHeight * width / previewWidth;
                mCameraView.layout(0, height - scaledChildHeight, width, height);
            }
        }

        /**
         *
         * @param sizes
         * @param width
         * @param height
         * @return
         */
        private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int width, int height)
        {
            final double ASPECT_TOLERANCE = 0.1;
            double targetRatio = (double) height / width;

            if (sizes == null)
                return null;

            Camera.Size optimalSize = null;
            double minDiff = Double.MAX_VALUE;

            int targetHeight = height;

            for (Camera.Size size : sizes) {
                double ratio = (double) size.height / size.width;
                if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
                    continue;

                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }

            if (optimalSize == null) {
                minDiff = Double.MAX_VALUE;
                for (Camera.Size size : sizes) {
                    if (Math.abs(size.height - targetHeight) < minDiff) {
                        optimalSize = size;
                        minDiff = Math.abs(size.height - targetHeight);
                    }
                }
            }

            return optimalSize;
        }
    }

    /**
     * Picture Callback for handling a picture capture and saving it out to a file.
     */
    private Camera.PictureCallback mPicture = new Camera.PictureCallback() {

        @Override
        public void onPictureTaken(byte[] data, Camera camera) {

            File pictureFile = getOutputMediaFile();
            if (pictureFile == null){
                Toast.makeText(getActivity(), "Image retrieval failed.", Toast.LENGTH_SHORT)
                        .show();
                return;
            }

            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    };

    /**
     * Used to return the camera File output.
     * @return
     */
    private File getOutputMediaFile(){

        File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "Pocket Booth");

        if (! mediaStorageDir.exists()){
            if (! mediaStorageDir.mkdirs()){
                Log.d("Camera Guide", "Required media storage does not exist");
                return null;
            }
        }

        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        File mediaFile;
        mediaFile = new File(mediaStorageDir.getPath() + File.separator +
                "IMG_"+ timeStamp + ".jpg");

        //DialogHelper.showDialog( "Success!","Your picture has been saved!",getActivity());

        return mediaFile;
    }
}