android-camera2相機開發【6】-拍照&屏幕旋轉適配

時間  2019-11-30
標籤 android camera2 camera 相機 開發 拍照 屏幕 旋轉 適配 欄目 Android 简体版
原文   原文鏈接

前面幾篇文章實現了相機的預覽，對預覽中出現的問題及須要注意的事項進行了梳理。java

本篇文章對相機的拍照流程、拍照方向及屏幕旋轉時的適配問題進行梳理。android

初始化相機和view

這裏選擇最大的相機輸出尺寸做爲拍照尺寸和預覽尺寸。git

@Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        initCamera();

        initViews(view);
    }
    
    private void initCamera() {
        cameraManager = CameraUtils.getInstance().getCameraManager();
        cameraId = CameraUtils.getInstance().getBackCameraId();
        outputSizes = CameraUtils.getInstance().getCameraOutputSizes(cameraId, SurfaceTexture.class);
        photoSize = outputSizes.get(0);
    }

    private void initViews(View view) {
        btnPhoto = view.findViewById(R.id.btn_photo);
        btnPhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takePhoto();
            }
        });

        previewView = view.findViewById(R.id.preview_view);
    }
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啓動/釋放相機

在 fragment 的 onResume 生命週期函數中啓動相機，在 onPause 中釋放相機。github

@Override
    public void onResume() {
        super.onResume();
        if (previewView.isAvailable()) {
            openCamera();
        } else {
            previewView.setSurfaceTextureListener(surfaceTextureListener);
        }
    }

    @Override
    public void onPause() {
        releaseCamera();
        super.onPause();
    }
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屏幕旋轉時適配預覽窗口和方向

啓動相機時須要根據此時屏幕的顯示方向（橫屏/豎屏）調整預覽窗口的大小和顯示方向。session

  • 調整預覽窗口的大小，能夠參考以前解決預覽界面拉伸的文章，裏面有描述。
  • 調整預覽方向：計算出預覽窗口到相機輸出窗口的變換矩陣。
    • 先將兩個窗口的中心平移到同一點；
    • 設置兩窗口縮放模式；
    • 計算縮放比例和旋轉角度；
    • 將變換矩陣應用到預覽窗口上。
@SuppressLint("MissingPermission")
    private void openCamera() {
        if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA)
                != PackageManager.PERMISSION_GRANTED) {
            requestCameraPermission();
        } else {
            try {
                //根據屏幕的顯示方向調整預覽窗口大小
                displayRotation = ((Activity) getContext()).getWindowManager().getDefaultDisplay().getOrientation();
                if (displayRotation == Surface.ROTATION_0 || displayRotation == Surface.ROTATION_180) {
                    previewView.setAspectRation(photoSize.getHeight(), photoSize.getWidth());
                }else {
                    previewView.setAspectRation(photoSize.getWidth(), photoSize.getHeight());
                }
                //根據屏幕的顯示方向調整預覽方向
                configureTransform(previewView.getWidth(), previewView.getHeight());
                cameraManager.openCamera(cameraId, cameraStateCallback, null);
            } catch (CameraAccessException e) {
                e.printStackTrace();
                Log.d(TAG, "相機訪問異常");
            }
        }
    }
    
    private void configureTransform(int viewWidth, int viewHeight) {
        Activity activity = getActivity();
        if (null == previewView || null == photoSize || null == activity) {
            return;
        }
        int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
        Matrix matrix = new Matrix();
        RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
        RectF bufferRect = new RectF(0, 0, photoSize.getHeight(), photoSize.getWidth());
        float centerX = viewRect.centerX();
        float centerY = viewRect.centerY();
        if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
            bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
            matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
            float scale = Math.max(
                    (float) viewHeight / photoSize.getHeight(),
                    (float) viewWidth / photoSize.getWidth());
            matrix.postScale(scale, scale, centerX, centerY);
            matrix.postRotate(90 * (rotation - 2), centerX, centerY);
        } else if (Surface.ROTATION_180 == rotation) {
            matrix.postRotate(180, centerX, centerY);
        }
        previewView.setTransform(matrix);
    }
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surfaceTextureListener 以前的文章也提過，這裏給出代碼app

TextureView.SurfaceTextureListener surfaceTextureListener = new TextureView.SurfaceTextureListener() {
        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
            //啓動相機
            openCamera();
        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
            configureTransform(width, height);
        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
            return false;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture surface) {

        }
    };
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還有相機打開的狀態回調監聽，成功打開後，初始化預覽、拍照用的Surface 以及 保存拍照數據用的 ImageReader。ide

CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(CameraDevice camera) {
            Log.d(TAG, "相機已啓動");
            //初始化拍照用的 ImageReader 和 Surface
            initReaderAndSurface();

            cameraDevice = camera;
            try {
                //初始化預覽 Surface
                SurfaceTexture surfaceTexture = previewView.getSurfaceTexture();
                if (surfaceTexture == null){
                    return;
                }

                surfaceTexture.setDefaultBufferSize(photoSize.getWidth(), photoSize.getHeight());//設置SurfaceTexture緩衝區大小
                previewSurface = new Surface(surfaceTexture);

                previewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                previewRequestBuilder.addTarget(previewSurface);
                previewRequest = previewRequestBuilder.build();

                cameraDevice.createCaptureSession(Arrays.asList(previewSurface, photoSurface), sessionsStateCallback, null);
            } catch (CameraAccessException e) {
                e.printStackTrace();
                Log.d(TAG, "相機訪問異常");
            }
        }

        @Override
        public void onDisconnected(CameraDevice camera) {
            Log.d(TAG, "相機已斷開鏈接");
        }

        @Override
        public void onError(CameraDevice camera, int error) {
            Log.d(TAG, "相機打開出錯");
        }
    };
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須要注意的是別忘了給 ImageReader 添加監聽器。 當拍照數據可用時會回調該監聽，在監聽的回調方法中，添加圖片的處理保存邏輯便可。函數

private void initReaderAndSurface() {

        //初始化拍照 ImageReader
        photoReader = ImageReader.newInstance(photoSize.getWidth(), photoSize.getHeight(), ImageFormat.JPEG, 2);
        photoReader.setOnImageAvailableListener(photoReaderImgListener, null);
        photoSurface = photoReader.getSurface();
    }
    
    ImageReader.OnImageAvailableListener photoReaderImgListener = new ImageReader.OnImageAvailableListener() {
        @Override
        public void onImageAvailable(ImageReader reader) {
            writeImageToFile();
        }
    };
    
    private void writeImageToFile() {
        if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) {
            requestStoragePermission();
        } else {
            String filePath = Environment.getExternalStorageDirectory() + "/DCIM/Camera/001.jpg";
            Image image = photoReader.acquireNextImage();
            if (image == null) {
                return;
            }
            ByteBuffer byteBuffer = image.getPlanes()[0].getBuffer();
            byte[] data = new byte[byteBuffer.remaining()];
            byteBuffer.get(data);
            FileOutputStream fos = null;
            try {
                fos = new FileOutputStream(new File(filePath));
                fos.write(data);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    fos.close();
                    fos = null;
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    image.close();
                    image = null;
                }
            }
        }
    }
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相機會話狀態回調以前也說明過，在會話建立成功時，開始重複請求，以得到連續的預覽。post

CameraCaptureSession.StateCallback sessionsStateCallback = new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(CameraCaptureSession session) {
            if (null == cameraDevice) {
                return;
            }

            captureSession = session;
            try {
                captureSession.setRepeatingRequest(previewRequest, null, null);
            } catch (CameraAccessException e) {
                e.printStackTrace();
                Log.d(TAG, "相機訪問異常");
            }
        }

        @Override
        public void onConfigureFailed(CameraCaptureSession session) {
            Log.d(TAG, "會話註冊失敗");
        }
    };
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拍照

通過上述步驟，能夠在屏幕旋轉時也能保證正常的預覽窗口大小和預覽方向。ui

拍照按鈕的點擊事件監聽函數 takePhoto() 主要有三個步驟。

  • 首先須要根據屏幕顯示方向，矯正拍照方向
  • 而後中止相機預覽，建立拍照請求進行拍照
  • 拍照成功後，重啓相機預覽

其中，屏幕顯示方向和拍照方向的對應關係用 PHOTO_ORTATION 定義。

private static final SparseIntArray PHOTO_ORITATION = new SparseIntArray();

    static {
        PHOTO_ORITATION.append(Surface.ROTATION_0, 90);
        PHOTO_ORITATION.append(Surface.ROTATION_90, 0);
        PHOTO_ORITATION.append(Surface.ROTATION_180, 270);
        PHOTO_ORITATION.append(Surface.ROTATION_270, 180);
    }
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private void takePhoto() {
        try {
            photoRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
            cameraOritation = PHOTO_ORITATION.get(displayRotation);
            photoRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, cameraOritation);
            photoRequestBuilder.addTarget(photoSurface);
            photoRequest = photoRequestBuilder.build();

            captureSession.stopRepeating();
            captureSession.capture(photoRequest, sessionCaptureCallback, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
            Log.d(TAG, "相機訪問異常");
        }
    }
    

    CameraCaptureSession.CaptureCallback sessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {
        @Override
        public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
            try {
                captureSession.setRepeatingRequest(previewRequest, null, null);
            } catch (CameraAccessException e) {
                e.printStackTrace();
                Log.d(TAG, "相機訪問異常");
            }
        }
    };
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總結

整個流程並非多複雜，主要就是要注意手機屏幕旋轉時的預覽窗口、方向適配，以及拍照方向的矯正。

到目前爲止，相機預覽、拍照方面的流程和注意事項基本梳理完畢，後續梳理相機特性控制和錄像方面的知識。

項目github地址

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