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项目github地址 前面几篇文章实现了相机的预览，对预览中出现的问题及需要注意的事项进行了梳理。 本篇文章对相机的拍照流程、拍照方向及屏幕旋转时的适配问题进行梳理。 初始化相机和view这里选择最大的相机输出尺寸作为拍照尺寸和预览尺寸。 @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); } 启动/释放相机在 fragment 的 onResume 生命周期函数中启动相机，在 onPause 中释放相机。 @Override public void onResume() { super.onResume(); if (previewView.isAvailable()) { openCamera(); } else { previewView.setSurfaceTextureListener(surfaceTextureListener); } } @Override public void onPause() { releaseCamera(); super.onPause(); } 屏幕旋转时适配预览窗口和方向启动相机时需要根据此时屏幕的显示方向（横屏/竖屏）调整预览窗口的大小和显示方向。 调整预览窗口的大小，可以参考之前解决预览界面拉伸的文章，里面有描述。调整预览方向：计算出预览窗口到相机输出窗口的变换矩阵。 先将两个窗口的中心平移到同一点；设置两窗口缩放模式；计算缩放比例和旋转角度；将变换矩阵应用到预览窗口上。 @SuppressLint("MissingPermission") private void openCamera() { if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { requestCameraPermission(); } else { try { //根据屏幕的显示方向调整预览窗口大小 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()); } //根据屏幕的显示方向调整预览方向 configureTransform(previewView.getWidth(), previewView.getHeight()); cameraManager.openCamera(cameraId, cameraStateCallback, null); } catch (CameraAccessException e) { e.printStackTrace(); Log.d(TAG, "相机访问异常"); } } } 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); }surfaceTextureListener 之前的文章也提过，这里给出代码 TextureView.SurfaceTextureListener surfaceTextureListener = new TextureView.SurfaceTextureListener() { @Override public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) { //启动相机 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) { } };还有相机打开的状态回调监听，成功打开后，初始化预览、拍照用的Surface 以及 保存拍照数据用的 ImageReader。 CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() { @Override public void onOpened(CameraDevice camera) { Log.d(TAG, "相机已启动"); //初始化拍照用的 ImageReader 和 Surface initReaderAndSurface(); cameraDevice = camera; try { //初始化预览 Surface SurfaceTexture surfaceTexture = previewView.getSurfaceTexture(); if (surfaceTexture == null){ return; } surfaceTexture.setDefaultBufferSize(photoSize.getWidth(), photoSize.getHeight());//设置SurfaceTexture缓冲区大小 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, "相机访问异常"); } } @Override public void onDisconnected(CameraDevice camera) { Log.d(TAG, "相机已断开连接"); } @Override public void onError(CameraDevice camera, int error) { Log.d(TAG, "相机打开出错"); } };需要注意的是别忘了给 ImageReader 添加监听器。 当拍照数据可用时会回调该监听，在监听的回调方法中，添加图片的处理保存逻辑即可。 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; } } } }相机会话状态回调之前也说明过，在会话创建成功时，开始重复请求，以获得连续的预览。 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, "相机访问异常"); } } @Override public void onConfigureFailed(CameraCaptureSession session) { Log.d(TAG, "会话注册失败"); } }; 拍照经过上述步骤，可以在屏幕旋转时也能保证正常的预览窗口大小和预览方向。 拍照按钮的点击事件监听函数 takePhoto() 主要有三个步骤。 首先需要根据屏幕显示方向，矫正拍照方向然后停止相机预览，创建拍照请求进行拍照拍照成功后，重启相机预览其中，屏幕显示方向和拍照方向的对应关系用 PHOTO_ORTATION 定义。 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); } 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, "相机访问异常"); } } 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, "相机访问异常"); } } }; 总结整个流程并不是多复杂，主要就是要注意手机屏幕旋转时的预览窗口、方向适配，以及拍照方向的矫正。 到目前为止，相机预览、拍照方面的流程和注意事项基本梳理完毕，后续梳理相机特性控制和录像方面的知识。 |
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