android-camera2相机开发-6-拍照&屏幕旋转适配 android相机开发

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 = https://www.it610.com/article/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。
【android-camera2相机开发-6-拍照&屏幕旋转适配】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。