android Camera2Basic源码分析
在Android源码的aosp/developers/build/prebuilts/gradle/目录下有几个camera相关的使用示例APP项目，Camera2Basic，Camera2Raw，Camera2Video，这些APP是google官方写的应用与不同的应用场景camera使用示例，本文讲Camera2Basic示例源码，此示例只能使用后置摄像头。
但最近在项目中要做一个camera功能的老化测试，测试规则是先打后摄像头预览5秒自动拍照，拍完后过5秒自动切换至前摄像头，再过5秒前摄像头自动拍照，拍完过5秒两款自动切至后摄像头，如此循环老化4小时，而此Camera2Basic示例默认只可用后摄像头拍照，所以还得自己再修改一下，之前对camera模块了解甚少，所以得大致了解了一下camera的使用，在此记录下：
CameraManager：
摄像头管理器。这是一个全新的系统管理器，专门用于检测系统摄像头、打开系统摄像头。另外，调用CameraManager的getCameraCharacteristics(String cameraId)方法即可获取指定摄像头的相关特性。
CameraCharacteristics：
摄像头特性。该对象通过CameraManager来获取，用于描述特定摄像头所支持的各种特性。类似与原来的CameraInfo 。
CameraDevice：
代表系统摄像头。该类的功能类似于早期的Camera类。而每个CameraDevice自己会负责创建CameraCaptureSession 以及建立 CaptureRequest。
CameraCaptureSession：
这是一个非常重要的API，当程序需要预览、拍照时，都需要先通过该类的实例创建Session。而且不管预览还是拍照，也都是由该对象的方法进行控制的，其中控制预览的方法为setRepeatingRequest()；控制拍照的方法为capture()。为了监听CameraCaptureSession的创建过程，以及监听CameraCaptureSession的拍照过程，Camera-v2-API为CameraCaptureSession提供了StateCallback、CaptureCallback等内部类。系统向摄像头发送 Capture 请求，而摄像头会返回 CameraMetadata，这一切建立在一个叫作 CameraCaptureSession 的会话中。
CameraCaptureSession.StateCallback状态回调
用于接收有关CameraCaptureSession状态的更新的回调对象，主要回调方法有两个当CameraDevice 完成配置，对应的会话开始处理捕获请求时触发onConfigured(CameraCaptureSession session)方法，反之配置失败时候触发onConfigureFailed(CameraCaptureSession session)方法。
CameraCaptureSession.CaptureCallback捕获回调
用于接收捕获请求状态的回调，当请求触发捕获已启动时；捕获完成时；在捕获图像时发生错误的情况下；都会触发该回调对应的方法。
CameraRequest和CameraRequest.Builder：
当程序调用setRepeatingRequest()方法进行预览时，或调用capture()方法进行拍照时，都需要传入CameraRequest参数。调用stopRepeating()实现停止捕获图像，即停止预览。CameraRequest代表了一次捕获请求，用于描述捕获图片的各种参数设置，比如对焦模式、曝光模式……总之，程序需要对照片所做的各种控制，都通过CameraRequest参数进行设置。CameraRequest.Builder则负责生成CameraRequest对象。
CaptureRequest
主要包括通过createCaptureRequest（int templateType）创建捕获请求，在需要预览、拍照、再次预览的时候都需要通过创建请求来完成。
CaptureResult
描述是从图像传感器捕获单个图像的结果的子集的对象。
上图所示, Camera APP 通过CameraCaptureSession发送CaptureRequest, CameraDevices收到请求后返回对应数据到对应的Surface,预览数据一般都是到TextureView, 拍照数据则在ImageReader中, 整体来说就是一个请求--响应过程, 请求完成后
//相对于SurfaceView, TextureView更适合用于视频和拍摄照片
public class xxxxx extends Fragment {
/**
* Conversion from screen rotation to JPEG orientation.
*/
private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
private static final int REQUEST_CAMERA_PERMISSION = 1;
private static final String FRAGMENT_DIALOG = "dialog";
private CaptureHandler mCaptureHandler;
private static CameraBurnInFragment CameraBurnInFragmentInstance = null;
static {
ORIENTATIONS.append(Surface.ROTATION_0, 90);
ORIENTATIONS.append(Surface.ROTATION_90, 0);
ORIENTATIONS.append(Surface.ROTATION_180, 270);
ORIENTATIONS.append(Surface.ROTATION_270, 180);
}
/**
* Tag for the {@link Log}.
*/
private static final String TAG = "Camera2BasicFragment";
/**
* Camera state: Showing camera preview.
*/
private static final int STATE_PREVIEW = 0;
/**
* Camera state: Waiting for the focus to be locked.
*/
private static final int STATE_WAITING_LOCK = 1;
/**
* Camera state: Waiting for the exposure to be precapture state.
*/
private static final int STATE_WAITING_PRECAPTURE = 2;
/**
* Camera state: Waiting for the exposure state to be something other than precapture.
*/
private static final int STATE_WAITING_NON_PRECAPTURE = 3;
/**
* Camera state: Picture was taken.
*/
private static final int STATE_PICTURE_TAKEN = 4;
/**
* Max preview width that is guaranteed by Camera2 API
*/
private static final int MAX_PREVIEW_WIDTH = 1920;
/**
* Max preview height that is guaranteed by Camera2 API
*/
private static final int MAX_PREVIEW_HEIGHT = 1080;
/**
* {@link TextureView.SurfaceTextureListener} handles several lifecycle events on a
* {@link TextureView}.
*/
private final TextureView.SurfaceTextureListener mSurfaceTextureListener
= new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
openCamera(width, height);
}
@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
configureTransform(width, height);
}
@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
return true;
}
@Override
public void onSurfaceTextureUpdated(SurfaceTexture texture) {
}
};
/**
* ID of the current {@link CameraDevice}.
*/
private String mCameraId;
/**
* An {@link AutoFitTextureView} for camera preview.
*/
private AutoFitTextureView mTextureView;
/**
* A {@link CameraCaptureSession } for camera preview.
*/
private CameraCaptureSession mCaptureSession;
/**
* A reference to the opened {@link CameraDevice}.
*/
private CameraDevice mCameraDevice;
/**
* The {@link Size} of camera preview.
*/
private Size mPreviewSize;
/**
* {@link CameraDevice.StateCallback} is called when {@link CameraDevice} changes its state.
*/
//通过CameraDevice.StateCallback监听摄像头的状态（主要onOpened、onClosed、onDisconnected、onErro四种状态）
//当摄像头被打开之后会回调接口mStateCallback.onOpened
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
// This method is called when the camera is opened. We start camera preview here.
mCameraOpenCloseLock.release();
////回调中得到CameraDevice
mCameraDevice = cameraDevice;
createCameraPreviewSession();
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
Activity activity = getActivity();
if (null != activity) {
activity.finish();
}
}
};
/**
* An additional thread for running tasks that shouldn't block the UI.
*/
private HandlerThread mBackgroundThread;
/**
* A {@link Handler} for running tasks in the background.
*/
private Handler mBackgroundHandler;
/**
* An {@link ImageReader} that handles still image capture.
*/
private ImageReader mImageReader;
/**
* This is the output file for our picture.
*/
private static File mFile;
/**
* This a callback object for the {@link ImageReader}. "onImageAvailable" will be called when a
* still image is ready to be saved.
*/
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener
= new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage()));//// 拿到拍照照片数据
}
};
/**
* {@link CaptureRequest.Builder} for the camera preview
*/
private CaptureRequest.Builder mPreviewRequestBuilder;
/**
* {@link CaptureRequest} generated by {@link #mPreviewRequestBuilder}
*/
private CaptureRequest mPreviewRequest;
/**
* The current state of camera state for taking pictures.
*
* @see #mCaptureCallback
*/
private int mState = STATE_PREVIEW;
/**
* A {@link Semaphore} to prevent the app from exiting before closing the camera.
*/
private Semaphore mCameraOpenCloseLock = new Semaphore(1);
/**
* Whether the current camera device supports Flash or not.
*/
private boolean mFlashSupported;
/**
* Orientation of the camera sensor
*/
private int mSensorOrientation;
/**
* A {@link CameraCaptureSession.CaptureCallback} that handles events related to JPEG capture.
*/
private CameraCaptureSession.CaptureCallback mCaptureCallback = new CameraCaptureSession.CaptureCallback() {
private void process(CaptureResult result) {
switch (mState) {
case STATE_PREVIEW: {
// We have nothing to do when the camera preview is working normally.
break;
}
case STATE_WAITING_LOCK: {
Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
if (afState == null) {
captureStillPicture();
} else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
// CONTROL_AE_STATE can be null on some devices
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
} else {
runPrecaptureSequence();
}
}
break;
}
case STATE_WAITING_PRECAPTURE: {
// CONTROL_AE_STATE can be null on some devices
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
mState = STATE_WAITING_NON_PRECAPTURE;
}
break;
}
case STATE_WAITING_NON_PRECAPTURE: {
// CONTROL_AE_STATE can be null on some devices
Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
mState = STATE_PICTURE_TAKEN;
captureStillPicture();
}
break;
}
}
}
@Override
public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request,
@NonNull CaptureResult partialResult) {
process(partialResult);
}
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
process(result);
}
};
/**
* Shows a {@link Toast} on the UI thread.
*
* @param text The message to show
*/
private void showToast(final String text) {
final Activity activity = getActivity();
if (activity != null) {
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(activity, text, Toast.LENGTH_SHORT).show();
}
});
}
}
/**
* Given {@code choices} of {@code Size}s supported by a camera, choose the smallest one that
* is at least as large as the respective texture view size, and that is at most as large as the
* respective max size, and whose aspect ratio matches with the specified value. If such size
* doesn't exist, choose the largest one that is at most as large as the respective max size,
* and whose aspect ratio matches with the specified value.
*
* @param choices The list of sizes that the camera supports for the intended output
* class
* @param textureViewWidth The width of the texture view relative to sensor coordinate
* @param textureViewHeight The height of the texture view relative to sensor coordinate
* @param maxWidth The maximum width that can be chosen
* @param maxHeight The maximum height that can be chosen
* @param aspectRatio The aspect ratio
* @return The optimal {@code Size}, or an arbitrary one if none were big enough
*/
private static Size chooseOptimalSize(Size[] choices, int textureViewWidth, int textureViewHeight, int maxWidth, int maxHeight, Size aspectRatio) {
// Collect the supported resolutions that are at least as big as the preview Surface
List<Size> bigEnough = new ArrayList<>();
// Collect the supported resolutions that are smaller than the preview Surface
List<Size> notBigEnough = new ArrayList<>();
int w = aspectRatio.getWidth();
int h = aspectRatio.getHeight();
for (Size option : choices) {
if (option.getWidth() <= maxWidth && option.getHeight() <= maxHeight &&
option.getHeight() == option.getWidth() * h / w) {
if (option.getWidth() >= textureViewWidth &&
option.getHeight() >= textureViewHeight) {
bigEnough.add(option);
} else {
notBigEnough.add(option);
}
}
}
// Pick the smallest of those big enough. If there is no one big enough, pick the
// largest of those not big enough.
if (bigEnough.size() > 0) {
return Collections.min(bigEnough, new CompareSizesByArea());
} else if (notBigEnough.size() > 0) {
return Collections.max(notBigEnough, new CompareSizesByArea());
} else {
Log.e(TAG, "Couldn't find any suitable preview size");
return choices[0];
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.camera_fragment, container, false);
}
@Override
public void onViewCreated(final View view, Bundle savedInstanceState) {
mTextureView = (AutoFitTextureView) view.findViewById(R.id.texture);
}
@Override
public void onResume() {
super.onResume();
startBackgroundThread();////开启一个后台线程处理相机数据
if (mTextureView.isAvailable()) {//如何镜头可用就直接open
openCamera(mTextureView.getWidth(), mTextureView.getHeight());
} else {//如果不可用，则开启它的可用时监听。
mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);
}
mCaptureHandler.captureImage();
}
@Override
public void onPause() {
closeCamera();
stopBackgroundThread();
super.onPause();
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == REQUEST_CAMERA_PERMISSION) {
if (grantResults.length != 1 || grantResults[0] != PackageManager.PERMISSION_GRANTED) {
ErrorDialog.newInstance(getString(R.string.request_permission)).show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
} else {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
private void requestCameraPermission() {
if (shouldShowRequestPermissionRationale(Manifest.permission.CAMERA)) {
new ConfirmationDialog().show(getChildFragmentManager(), FRAGMENT_DIALOG);
} else {
requestPermissions(new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
}
}
/**
* Sets up member variables related to camera.
*
* @param width The width of available size for camera preview
* @param height The height of available size for camera preview
*/
@SuppressWarnings("SuspiciousNameCombination")
private void setUpCameraOutputs(int width, int height) {
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
for (String cameraId : manager.getCameraIdList()) {
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
// We don't use a front facing camera in this sample.
Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
//if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
// continue;
//}
//得到该摄像头设备支持的可用流配置；还包括各种格式/尺寸组合的最小帧时长和停顿时长
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
if (map == null) {
continue;
}
// For still image captures, we use the largest available size.
//// 对于静态图像捕获，我们使用最大的可用大小。
Size largest = Collections.max(Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)), new CompareSizesByArea());
//设置ImageReader接收的图片格式，以及允许接收的最大图片数目
mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(), ImageFormat.JPEG, /*maxImages*/2);
//设置图片存储的监听
mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mBackgroundHandler);
// Find out if we need to swap dimension to get the preview size relative to sensor
// coordinate.
int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
//noinspection ConstantConditions
mSensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
boolean swappedDimensions = false;
switch (displayRotation) {
case Surface.ROTATION_0:
case Surface.ROTATION_180:
if (mSensorOrientation == 90 || mSensorOrientation == 270) {
swappedDimensions = true;
}
break;
case Surface.ROTATION_90:
case Surface.ROTATION_270:
if (mSensorOrientation == 0 || mSensorOrientation == 180) {
swappedDimensions = true;
}
break;
default:
Log.e(TAG, "Display rotation is invalid: " + displayRotation);
}
Point displaySize = new Point();
activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
int rotatedPreviewWidth = width;
int rotatedPreviewHeight = height;
int maxPreviewWidth = displaySize.x;
int maxPreviewHeight = displaySize.y;
if (swappedDimensions) {
rotatedPreviewWidth = height;
rotatedPreviewHeight = width;
maxPreviewWidth = displaySize.y;
maxPreviewHeight = displaySize.x;
}
if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
maxPreviewWidth = MAX_PREVIEW_WIDTH;
}
if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
maxPreviewHeight = MAX_PREVIEW_HEIGHT;
}
// Danger, W.R.! Attempting to use too large a preview size could exceed the camera
// bus' bandwidth limitation, resulting in gorgeous previews but the storage of
// garbage capture data.
// 危险！尝试使用太大的预览大小可能会超出相机总线的带宽限制，导致华丽的预览，但会存储垃圾捕获数据
mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
maxPreviewHeight, largest);
// We fit the aspect ratio of TextureView to the size of preview we picked.
// 我们将TextureView的宽高比与我们选择的预览大小相匹配。
int orientation = getResources().getConfiguration().orientation;
if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
mTextureView.setAspectRatio(mPreviewSize.getWidth(), mPreviewSize.getHeight());
} else {
mTextureView.setAspectRatio(mPreviewSize.getHeight(), mPreviewSize.getWidth());
}
// Check if the flash is supported.
Boolean available = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
mFlashSupported = available == null ? false : available;
mCameraId = cameraId;
return;
}
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (NullPointerException e) {
// Currently an NPE is thrown when the Camera2API is used but not supported on the
// device this code runs.
ErrorDialog.newInstance(getString(R.string.camera_error))
.show(getChildFragmentManager(), FRAGMENT_DIALOG);
}
}
/**
* Opens the camera specified by {@link CameraBurnInFragment#mCameraId}.
*/
//打开相机成功的话，获取CameraDevice，然后创建会话–createCameraPreviewSession()，通过mTextureView获取SurfaceTexture，
//通过SurafceTexture获得Surface对象，在CaptureRequest.Builder中添加Surface然后创建会话，
//获得CaptureRequest对象，通过CaptureRequest发送重复请求捕捉画面，开启预览。
private void openCamera(int width, int height) {
if (activity.checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
requestCameraPermission();
return;
}
setUpCameraOutputs(width, height);
configureTransform(width, height);
Activity activity = getActivity();
CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
try {
if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
throw new RuntimeException("Time out waiting to lock camera opening.");
}
//manager.openCamera 调用此方法会回调进入到mStateCallback对象的匿名类中
// 该方法的第一个参数代表要打开的摄像头ID；
// 第二个参数用于监听摄像头的状态；
// 第三个参数代表执行callback的Handler，如果程序希望直接在当前线程中执行callback，则可将handler参数设为null。
manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
}
}
/**
* Closes the current {@link CameraDevice}.
*/
private void closeCamera() {
try {
mCameraOpenCloseLock.acquire();
if (null != mCaptureSession) {
mCaptureSession.close();
mCaptureSession = null;
}
if (null != mCameraDevice) {
mCameraDevice.close();
mCameraDevice = null;
}
if (null != mImageReader) {
mImageReader.close();
mImageReader = null;
}
} catch (InterruptedException e) {
throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
} finally {
mCameraOpenCloseLock.release();
}
}
/**
* Starts a background thread and its {@link Handler}.
*/
private void startBackgroundThread() {
mCaptureHandler = new CaptureHandler();
mBackgroundThread = new HandlerThread("CameraBackground");
mBackgroundThread.start();
mBackgroundHandler = new Handler(mBackgroundThread.getLooper());
}
/**
* Stops the background thread and its {@link Handler}.
*/
private void stopBackgroundThread() {
if (null != mCaptureHandler) {
mCaptureHandler.removeCallbacksAndEqualMessages(null);
}
mBackgroundThread.quitSafely();
try {
mBackgroundThread.join();
mBackgroundThread = null;
mBackgroundHandler = null;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
/**
* Creates a new {@link CameraCaptureSession} for camera preview.
*/
private void createCameraPreviewSession() {
try {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
assert texture != null;
// We configure the size of default buffer to be the size of camera preview we want.
//我们将默认缓冲区的大小配置为所需的相机预览大小。
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// This is the output Surface we need to start preview.
Surface surface = new Surface(texture);
// We set up a CaptureRequest.Builder with the output Surface.
////创建预览需要的CaptureRequest.Builder设置拍照的各种参数，比如对焦模式、曝光模式等
//该方法支持TEMPLATE_PREVIEW（预览）、TEMPLATE_RECORD（拍摄视频）、TEMPLATE_STILL_CAPTURE（拍照）等参数
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
//将SurfaceTexture的surface作为CaptureRequest.Builder的目标
mPreviewRequestBuilder.addTarget(surface);
// Here, we create a CameraCaptureSession for camera preview.
//创建CameraCaptureSession，该对象负责管理处理预览请求和拍照请求
//第一个参数是一个List集合，封装了所有需要从该摄像头获取图片的Surface，//一个用于预览、一个用于拍照。有几个显示载体，就需要几个输出流
//第二个参数用于监听CameraCaptureSession的创建过程；
//第三个参数代表执行callback的Handler，如果程序希望直接在当前线程中执行callback，则可将handler参数设为null。
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// The camera is already closed
if (null == mCameraDevice) {
return;
}
// When the session is ready, we start displaying the preview.
// 当摄像头已经准备好时，开始显示预览
mCaptureSession = cameraCaptureSession;
try {
// Auto focus should be continuous for camera preview.
// 自动对焦
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
// Flash is automatically enabled when necessary.
setAutoFlash(mPreviewRequestBuilder);// 打开闪光灯
// 显示预览
// Finally, we start displaying the camera preview.
mPreviewRequest = mPreviewRequestBuilder.build();
//// 最后，我们开始显示相机预览。setRepeatingRequest表示可以不断发送请求.
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed( @NonNull CameraCaptureSession cameraCaptureSession) {
showToast("Failed");
}
}, null );
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* Configures the necessary {@link Matrix} transformation to `mTextureView`.
* This method should be called after the camera preview size is determined in
* setUpCameraOutputs and also the size of `mTextureView` is fixed.
*
* @param viewWidth The width of `mTextureView`
* @param viewHeight The height of `mTextureView`
*/
private void configureTransform(int viewWidth, int viewHeight) {
Activity activity = getActivity();
if (null == mTextureView || null == mPreviewSize || 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, mPreviewSize.getHeight(), mPreviewSize.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 / mPreviewSize.getHeight(),
(float) viewWidth / mPreviewSize.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);
}
mTextureView.setTransform(matrix);
}
/**
* Initiate a still image capture.
*/
private void takePicture() {
lockFocus();
}
/**
* Lock the focus as the first step for a still image capture.
*/
private void lockFocus() {
try {
// This is how to tell the camera to lock focus.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
// Tell #mCaptureCallback to wait for the lock.
mState = STATE_WAITING_LOCK;
//capture只发一次请求
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* Run the precapture sequence for capturing a still image. This method should be called when
* we get a response in {@link #mCaptureCallback} from {@link #lockFocus()}.
*/
private void runPrecaptureSequence() {
try {
// This is how to tell the camera to trigger.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER, CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START);
// Tell #mCaptureCallback to wait for the precapture sequence to be set.
mState = STATE_WAITING_PRECAPTURE;
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* Capture a still picture. This method should be called when we get a response in
* {@link #mCaptureCallback} from both {@link #lockFocus()}.
*/
private void captureStillPicture() {
try {
final Activity activity = getActivity();
if (null == activity || null == mCameraDevice) {
return;
}
// This is the CaptureRequest.Builder that we use to take a picture.
// 创建拍照需要的CaptureRequest.Builder
final CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
// 将imageReader的surface作为CaptureRequest.Builder的目标
captureBuilder.addTarget(mImageReader.getSurface());
// Use the same AE and AF modes as the preview.
// 自动对焦
captureBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
//自动曝光
setAutoFlash(captureBuilder);
// Orientation// 获取手机方向
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
// 根据设备方向计算设置照片的方向
captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, getOrientation(rotation));
CameraCaptureSession.CaptureCallback CaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session,
@NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
showToast("Saved: " + mFile);
////恢复预览
unlockFocus();
}
};
mCaptureSession.stopRepeating();
mCaptureSession.abortCaptures();
//拍照
mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
/**
* Retrieves the JPEG orientation from the specified screen rotation.
*
* @param rotation The screen rotation.
* @return The JPEG orientation (one of 0, 90, 270, and 360)
*/
private int getOrientation(int rotation) {
// Sensor orientation is 90 for most devices, or 270 for some devices (eg. Nexus 5X)
// We have to take that into account and rotate JPEG properly.
// For devices with orientation of 90, we simply return our mapping from ORIENTATIONS.
// For devices with orientation of 270, we need to rotate the JPEG 180 degrees.
return (ORIENTATIONS.get(rotation) + mSensorOrientation + 270) % 360;
}
/**
* Unlock the focus. This method should be called when still image capture sequence is
* finished.
*/
private void unlockFocus() {
try {
// Reset the auto-focus trigger
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
setAutoFlash(mPreviewRequestBuilder);
mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
// After this, the camera will go back to the normal state of preview.
mState = STATE_PREVIEW;
mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
private void setAutoFlash(CaptureRequest.Builder requestBuilder) {
if (mFlashSupported) {
requestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
}
}
/**
* Saves a JPEG {@link Image} into the specified {@link File}.
*/
private static class ImageSaver implements Runnable {
/**
* The JPEG image
*/
private final Image mImage;
ImageSaver(Image image) {
mImage = image;
}
@Override
public void run() {
String picName = new SimpleDateFormat("yyyyMMddHHmmss'_buinin.jpg'").format(new Date());
mFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), picName);
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();//// 拿到拍照照片数据
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(mFile);
output.write(bytes);
} catch (IOException e) {
e.printStackTrace();
} finally {
mImage.close();
if (null != output) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
scanFile(mFile);
}
private void scanFile(File visibleFile) {
final Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
intent.setData(Uri.fromFile(visibleFile));
activity.sendBroadcast(intent);
}
}
/**
* Compares two {@code Size}s based on their areas.
*/
static class CompareSizesByArea implements Comparator<Size> {
@Override
public int compare(Size lhs, Size rhs) {
// We cast here to ensure the multiplications won't overflow
return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
(long) rhs.getWidth() * rhs.getHeight());
}
}
/**
* Shows an error message dialog.
*/
public static class ErrorDialog extends DialogFragment {
private static final String ARG_MESSAGE = "message";
public static ErrorDialog newInstance(String message) {
ErrorDialog dialog = new ErrorDialog();
Bundle args = new Bundle();
args.putString(ARG_MESSAGE, message);
dialog.setArguments(args);
return dialog;
}
@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Activity activity = getActivity();
return new AlertDialog.Builder(activity)
.setMessage(getArguments().getString(ARG_MESSAGE))
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
activity.finish();
}
}).create();
}
}
/**
* Shows OK/Cancel confirmation dialog about camera permission.
*/
public static class ConfirmationDialog extends DialogFragment {
@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
final Fragment parent = getParentFragment();
return new AlertDialog.Builder(getActivity())
.setMessage(R.string.request_permission)
.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
parent.requestPermissions(new String[]{Manifest.permission.CAMERA},
REQUEST_CAMERA_PERMISSION);
}
})
.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Activity activity = parent.getActivity();
if (activity != null) {
activity.finish();
}
}
}).create();
}
}
}参考文献：
camera2 Google官方demo android-Camera2Basic解读
版权声明：如无特殊标注，文章均为本站原创，转载时请以链接形式注明文章出处。
评论