简介
frameworks\base\core\java\android\hardware\camera2
Camera2在Android 5.0上首次出现，主要重新定义了一套Camera 的使用接口API，设计思想出现了变化，具体的可自行搜索，此处主要介绍下Camera2的常见类以及使用流程。
CameraCaptureSession 类 会话类，即用户发起操作Camera设备的动作类，如录像拍照等
CaptureRequest类 请求类，用户对Camera发起请求的抽象封装类
CameraDevice类 Camera抽象类，类似于Camaera的一个客户端
CameraCharacteristics类 相机参数类，比如相机支持哪些特性，如分辨率集合等
除此之外这些类中还会存在内部类，内部类的作用是Camera Framework 层完成配置异步返回结果的抽象类
以上几个主要的类都在base/core下面，在对外发布API的时候App均可使用
frameworks\base\media
ImageReader类 相机采集回来的数据承载类，即相机的YUV元数据承载类
在APP层使用相机拍照 录制视频 等过程中上述主要类均离不开，本系列主要围绕关键类，介绍其关键流程，本文主要介绍openCamera流程
1： openCamera 基本流程
Framework层流程也是针对上诉几个关键步骤进行分析的，我们逐个往下分析
首先看下App层在openCamera的时候Framework层发生了什么，做了什么
frameworks\base\core\java\android\hardware\camera2\CameraManager.java
@RequiresPermission(android.Manifest.permission.CAMERA)
public void openCamera(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @Nullable Handler handler)
throws CameraAccessException {
openCameraForUid(cameraId, callback, handler, USE_CALLING_UID);
}
检查参数
public void openCameraForUid(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @Nullable Handler handler,
int clientUid)
throws CameraAccessException {
if(TdDeviceManager.disallowOp(TdDeviceManager.DISABLED_CAMERA)) {
throw new IllegalArgumentException("camera is disabled by MDM");
}
if (cameraId == null) {
throw new IllegalArgumentException("cameraId was null");
} else if (callback == null) {
throw new IllegalArgumentException("callback was null");
} else if (handler == null) {
if (Looper.myLooper() != null) {
handler = new Handler();
} else {
throw new IllegalArgumentException(
"Handler argument is null, but no looper exists in the calling thread");
}
}
openCameraDeviceUserAsync(cameraId, callback, handler, clientUid);
}
关键方法
/**
* Helper for opening a connection to a camera with the given ID.
*
* @param cameraId The unique identifier of the camera device to open
* @param callback The callback for the camera. Must not be null.
* @param handler The handler to invoke the callback on. Must not be null.
* @param uid The UID of the application actually opening the camera.
* Must be USE_CALLING_UID unless the caller is a service
* that is trusted to open the device on behalf of an
* application and to forward the real UID.
*
* @throws CameraAccessException if the camera is disabled by device policy,
* too many camera devices are already open, or the cameraId does not match
* any currently available camera device.
*
* @throws SecurityException if the application does not have permission to
* access the camera
* @throws IllegalArgumentException if callback or handler is null.
* @return A handle to the newly-created camera device.
*
* @see #getCameraIdList
* @see android.app.admin.DevicePolicyManager#setCameraDisabled
*/
private CameraDevice openCameraDeviceUserAsync(String cameraId,
CameraDevice.StateCallback callback, Handler handler, final int uid)
throws CameraAccessException {
CameraCharacteristics characteristics = getCameraCharacteristics(cameraId);
CameraDevice device = null;
synchronized (mLock) {
ICameraDeviceUser cameraUser = null;
android.hardware.camera2.impl.CameraDeviceImpl deviceImpl =
new android.hardware.camera2.impl.CameraDeviceImpl(
cameraId,
callback,
handler,
characteristics,
mContext.getApplicationInfo().targetSdkVersion);
ICameraDeviceCallbacks callbacks = deviceImpl.getCallbacks();
try {
if (supportsCamera2ApiLocked(cameraId)) {
// Use cameraservice's cameradeviceclient implementation for HAL3.2+ devices
//[HSM]
if(!HwSystemManager.allowOp(HwSystemManager.PERMISSION_CAMERA)) {
ServiceSpecificException e = new ServiceSpecificException(ICameraService.ERROR_DISABLED);
throwAsPublicException(e);
}
Log.i(TAG, "open camera: " + cameraId + ", package name: " + mContext.getOpPackageName());
HwSystemManager.notifyBackgroundMgr(mContext.getOpPackageName(),
Binder.getCallingPid(),
Binder.getCallingUid(),
HwSystemManager.CAMARA_SERVICE_NOTIFY,
HwSystemManager.BACKGROUND_POLICY_OPEN);
ICameraService cameraService = CameraManagerGlobal.get().getCameraService();
if (cameraService == null) {
throw new ServiceSpecificException(
ICameraService.ERROR_DISCONNECTED,
"Camera service is currently unavailable");
}
cameraUser = cameraService.connectDevice(callbacks, cameraId,
mContext.getOpPackageName(), uid);
} else {
// Use legacy camera implementation for HAL1 devices
int id;
try {
id = Integer.parseInt(cameraId);
} catch (NumberFormatException e) {
throw new IllegalArgumentException("Expected cameraId to be numeric, but it was: "
+ cameraId);
}
Log.i(TAG, "Using legacy camera HAL.");
cameraUser = CameraDeviceUserShim.connectBinderShim(callbacks, id);
}
} catch (ServiceSpecificException e) {
if (e.errorCode == ICameraService.ERROR_DEPRECATED_HAL) {
throw new AssertionError("Should've gone down the shim path");
} else if (e.errorCode == ICameraService.ERROR_CAMERA_IN_USE ||
e.errorCode == ICameraService.ERROR_MAX_CAMERAS_IN_USE ||
e.errorCode == ICameraService.ERROR_DISABLED ||
e.errorCode == ICameraService.ERROR_DISCONNECTED ||
e.errorCode == ICameraService.ERROR_INVALID_OPERATION) {
// Received one of the known connection errors
// The remote camera device cannot be connected to, so
// set the local camera to the startup error state
deviceImpl.setRemoteFailure(e);
if (e.errorCode == ICameraService.ERROR_DISABLED ||
e.errorCode == ICameraService.ERROR_DISCONNECTED ||
e.errorCode == ICameraService.ERROR_CAMERA_IN_USE) {
// Per API docs, these failures call onError and throw
throwAsPublicException(e);
}
} else {
// Unexpected failure - rethrow
throwAsPublicException(e);
}
} catch (RemoteException e) {
// Camera service died - act as if it's a CAMERA_DISCONNECTED case
ServiceSpecificException sse = new ServiceSpecificException(
ICameraService.ERROR_DISCONNECTED,
"Camera service is currently unavailable");
deviceImpl.setRemoteFailure(sse);
throwAsPublicException(sse);
}
// TODO: factor out callback to be non-nested, then move setter to constructor
// For now, calling setRemoteDevice will fire initial
// onOpened/onUnconfigured callbacks.
// This function call may post onDisconnected and throw CAMERA_DISCONNECTED if
// cameraUser dies during setup.
deviceImpl.setRemoteDevice(cameraUser);
device = deviceImpl;
}
return device;
}
关键部分代码如上，主要干了什么了？
1：创建了Camera Client 即 deviceImpl，此对象也就是返回APP进程中的对象
android.hardware.camera2.impl.CameraDeviceImpl deviceImpl =new android.hardware.camera2.impl.CameraDeviceImpl(cameraId, callback,handler,characteristics,mContext.getApplicationInfo().targetSdkVersion);
2：将第一步创建的Client 和Framework 的Camera Service 联系起来，并且注册了一个回调，在物理Camera实际有什么状态时，及时通知到App层
cameraUser = cameraService.connectDevice(callbacks, cameraId,
mContext.getOpPackageName(), uid);
3:将deviceImpl 和ICameraDeviceUser cameraUser联系起来，即App用户提过deviceImpl下发指令，deviceImpl 通过cameraUser 操作Framework层的 Camera，并且将Framework层的Camera的客户端返回给高层
deviceImpl.setRemoteDevice(cameraUser);
2：openCamera关键步骤
关键步骤1：
在CameraManager openCamera的时候就创建了给APP 用的Client，此Client初始化的参数关注下即可，主要是传了camera 的id（哪个摄像头），摄像头的回调接口callback，此接口在Camera创建完成就返回给APP进程了，handler是App处理相机打卡回调的接收者，此处关键就是Framework 返回App的是CameraDeviceImpl 对象，但是实际接口返回的要求是一个CameraDevice对象，如下：
/**
* The method called when a camera device has finished opening.
*
* <p>At this point, the camera device is ready to use, and
* {@link CameraDevice#createCaptureSession} can be called to set up the first capture
* session.</p>
*
* @param camera the camera device that has become opened
*/
public abstract void onOpened(@NonNull CameraDevice camera); // Must implement
关键步骤2：
此步骤是打开Camera的最关键的一步，首先是获取Framework层的Camera Service，即
ICameraService cameraService
ICameraService cameraService = CameraManagerGlobal.get().getCameraService();
然后就通过 cameraService
cameraUser = cameraService.connectDevice(callbacks, cameraId,
mContext.getOpPackageName(), uid);
主要传了 callback（Cameraservice 回调App的接口），Camera的id 进程号 和包名（下面代码删除了部分，主要说明此回调作用）
public class CameraDeviceCallbacks extends ICameraDeviceCallbacks.Stub {
@Override
public IBinder asBinder() {
return this;
}
@Override
public void onDeviceError(final int errorCode, CaptureResultExtras resultExtras) {
}
@Override
public void onRepeatingRequestError(long lastFrameNumber) {
}
@Override
public void onDeviceIdle() {
}
@Override
public void onCaptureStarted(final CaptureResultExtras resultExtras, final long timestamp) {
}
@Override
public void onResultReceived(CameraMetadataNative result,
}
@Override
public void onPrepared(int streamId) {
}
@Override
public void onRequestQueueEmpty() {
}
}
Callback对象，根据此对象定义可知是通过Binder传递过来的
通过Binder 调用Camera Service的connectDevice，Camera Service是Camera 进程初始化注册到ServicesManager中的，服务的承载代码即CameraService.cpp，因此查看下：
Status CameraService::connectDevice(
const sp<hardware::camera2::ICameraDeviceCallbacks>& cameraCb,
const String16& cameraId,
const String16& clientPackageName,
int clientUid,
/*out*/
sp<hardware::camera2::ICameraDeviceUser>* device) {
ATRACE_CALL();
Status ret = Status::ok();
String8 id = String8(cameraId);
sp<CameraDeviceClient> client = nullptr;
ret = connectHelper<hardware::camera2::ICameraDeviceCallbacks,CameraDeviceClient>(cameraCb, id,
CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageName,
clientUid, USE_CALLING_PID, API_2,
/*legacyMode*/ false, /*shimUpdateOnly*/ false,
/*out*/client);
if(!ret.isOk()) {
logRejected(id, getCallingPid(), String8(clientPackageName),
ret.toString8());
return ret;
}
String8 pid = String8::format("%d", getCallingPid());
POWERPUSH(129, clientName8.string(), id.string(), pid.string());//define in LogPower.java, 129 stand for camera start now
*device = client;
//add for send msg to nfc
char needSendMsg[255];
property_get("ro.config.hw_camera_nfc_switch",needSendMsg,"");
ALOGI("NFC polling %s", needSendMsg);
if (0 == strcmp(needSendMsg, "true")) {
String8 isOpen = String8::format("false");
android::allowNfcPolling(isOpen);
}
ALOGI("%s(), exit.", __FUNCTION__);
return ret;
}
关键函数connectHelper
template<class CALLBACK, class CLIENT>
Status CameraService::connectHelper(const sp<CALLBACK>& cameraCb, const String8& cameraId,
int halVersion, const String16& clientPackageName, int clientUid, int clientPid,
apiLevel effectiveApiLevel, bool legacyMode, bool shimUpdateOnly,
/*out*/sp<CLIENT>& device) {
binder::Status ret = binder::Status::ok();
String8 clientName8(clientPackageName);
int originalClientPid = 0;
ALOGI("CameraService::connect call (PID %d \"%s\", camera ID %s) for HAL version %s and "
"Camera API version %d", clientPid, clientName8.string(), cameraId.string(),
(halVersion == -1) ? "default" : std::to_string(halVersion).c_str(),
static_cast<int>(effectiveApiLevel));
sp<CLIENT> client = nullptr;
{
// Acquire mServiceLock and prevent other clients from connecting
std::unique_ptr<AutoConditionLock> lock =
AutoConditionLock::waitAndAcquire(mServiceLockWrapper, DEFAULT_CONNECT_TIMEOUT_NS);
if (lock == nullptr) {
ALOGE("CameraService::connect (PID %d) rejected (too many other clients connecting)."
, clientPid);
return STATUS_ERROR_FMT(ERROR_MAX_CAMERAS_IN_USE,
"Cannot open camera %s for \"%s\" (PID %d): Too many other clients connecting",
cameraId.string(), clientName8.string(), clientPid);
}
// Enforce client permissions and do basic sanity checks
if(!(ret = validateConnectLocked(cameraId, clientName8,
/*inout*/clientUid, /*inout*/clientPid, /*out*/originalClientPid)).isOk()) {
return ret;
}
// Check the shim parameters after acquiring lock, if they have already been updated and
// we were doing a shim update, return immediately
if (shimUpdateOnly) {
auto cameraState = getCameraState(cameraId);
if (cameraState != nullptr) {
if (!cameraState->getShimParams().isEmpty()) return ret;
}
}
status_t err;
sp<BasicClient> clientTmp = nullptr;
std::shared_ptr<resource_policy::ClientDescriptor<String8, sp<BasicClient>>> partial;
if ((err = handleEvictionsLocked(cameraId, originalClientPid, effectiveApiLevel,
IInterface::asBinder(cameraCb), clientName8, /*out*/&clientTmp,
/*out*/&partial)) != NO_ERROR) {
switch (err) {
case -ENODEV:
return STATUS_ERROR_FMT(ERROR_DISCONNECTED,
"No camera device with ID \"%s\" currently available",
cameraId.string());
case -EBUSY:
return STATUS_ERROR_FMT(ERROR_CAMERA_IN_USE,
"Higher-priority client using camera, ID \"%s\" currently unavailable",
cameraId.string());
default:
return STATUS_ERROR_FMT(ERROR_INVALID_OPERATION,
"Unexpected error %s (%d) opening camera \"%s\"",
strerror(-err), err, cameraId.string());
}
}
if (clientTmp.get() != nullptr) {
// Handle special case for API1 MediaRecorder where the existing client is returned
device = static_cast<CLIENT*>(clientTmp.get());
return ret;
}
// give flashlight a chance to close devices if necessary.
mFlashlight->prepareDeviceOpen(cameraId);
int facing = -1;
int deviceVersion = getDeviceVersion(cameraId, /*out*/&facing);
if (facing == -1) {
ALOGE("%s: Unable to get camera device \"%s\" facing", __FUNCTION__, cameraId.string());
return STATUS_ERROR_FMT(ERROR_INVALID_OPERATION,
"Unable to get camera device \"%s\" facing", cameraId.string());
}
sp<BasicClient> tmp = nullptr;
if(!(ret = makeClient(this, cameraCb, clientPackageName, cameraId, facing, clientPid,
clientUid, getpid(), legacyMode, halVersion, deviceVersion, effectiveApiLevel,
/*out*/&tmp)).isOk()) {
return ret;
}
client = static_cast<CLIENT*>(tmp.get());
ALOGI("%s(), make client for '%s'.", __FUNCTION__, String8{clientPackageName}.string());
LOG_ALWAYS_FATAL_IF(client.get() == nullptr, "%s: CameraService in invalid state",
__FUNCTION__);
err = client->initialize(mCameraProviderManager);
if (err != OK) {
ALOGE("%s: Could not initialize client from HAL.", __FUNCTION__);
// Errors could be from the HAL module open call or from AppOpsManager
switch(err) {
case BAD_VALUE:
return STATUS_ERROR_FMT(ERROR_ILLEGAL_ARGUMENT,
"Illegal argument to HAL module for camera \"%s\"", cameraId.string());
case -EBUSY:
return STATUS_ERROR_FMT(ERROR_CAMERA_IN_USE,
"Camera \"%s\" is already open", cameraId.string());
case -EUSERS:
return STATUS_ERROR_FMT(ERROR_MAX_CAMERAS_IN_USE,
"Too many cameras already open, cannot open camera \"%s\"",
cameraId.string());
case PERMISSION_DENIED:
return STATUS_ERROR_FMT(ERROR_PERMISSION_DENIED,
"No permission to open camera \"%s\"", cameraId.string());
case -EACCES:
return STATUS_ERROR_FMT(ERROR_DISABLED,
"Camera \"%s\" disabled by policy", cameraId.string());
case -ENODEV:
default:
return STATUS_ERROR_FMT(ERROR_INVALID_OPERATION,
"Failed to initialize camera \"%s\": %s (%d)", cameraId.string(),
strerror(-err), err);
}
}
// Update shim paremeters for legacy clients
if (effectiveApiLevel == API_1) {
// Assume we have always received a Client subclass for API1
sp<Client> shimClient = reinterpret_cast<Client*>(client.get());
String8 rawParams = shimClient->getParameters();
CameraParameters params(rawParams);
auto cameraState = getCameraState(cameraId);
if (cameraState != nullptr) {
cameraState->setShimParams(params);
} else {
ALOGE("%s: Cannot update shim parameters for camera %s, no such device exists.",
__FUNCTION__, cameraId.string());
}
}
if (shimUpdateOnly) {
// If only updating legacy shim parameters, immediately disconnect client
mServiceLock.unlock();
client->disconnect();
mServiceLock.lock();
} else {
// Otherwise, add client to active clients list
finishConnectLocked(client, partial);
}
} // lock is destroyed, allow further connect calls
device = client;
return ret;
}
关键函数makeClient
Status CameraService::makeClient(const sp<CameraService>& cameraService,
const sp<IInterface>& cameraCb, const String16& packageName, const String8& cameraId,
int facing, int clientPid, uid_t clientUid, int servicePid, bool legacyMode,
int halVersion, int deviceVersion, apiLevel effectiveApiLevel,
/*out*/sp<BasicClient>* client) {
if (halVersion < 0 || halVersion == deviceVersion) {
// Default path: HAL version is unspecified by caller, create CameraClient
// based on device version reported by the HAL.
switch(deviceVersion) {
case CAMERA_DEVICE_API_VERSION_1_0:
if (effectiveApiLevel == API_1) { // Camera1 API route
sp<ICameraClient> tmp = static_cast<ICameraClient*>(cameraCb.get());
*client = new CameraClient(cameraService, tmp, packageName, cameraIdToInt(cameraId),
facing, clientPid, clientUid, getpid(), legacyMode);
} else { // Camera2 API route
ALOGW("Camera using old HAL version: %d", deviceVersion);
return STATUS_ERROR_FMT(ERROR_DEPRECATED_HAL,
"Camera device \"%s\" HAL version %d does not support camera2 API",
cameraId.string(), deviceVersion);
}
break;
case CAMERA_DEVICE_API_VERSION_3_0:
case CAMERA_DEVICE_API_VERSION_3_1:
case CAMERA_DEVICE_API_VERSION_3_2:
case CAMERA_DEVICE_API_VERSION_3_3:
case CAMERA_DEVICE_API_VERSION_3_4:
if (effectiveApiLevel == API_1) { // Camera1 API route
sp<ICameraClient> tmp = static_cast<ICameraClient*>(cameraCb.get());
*client = new Camera2Client(cameraService, tmp, packageName, cameraIdToInt(cameraId),
facing, clientPid, clientUid, servicePid, legacyMode);
} else { // Camera2 API route
sp<hardware::camera2::ICameraDeviceCallbacks> tmp =
static_cast<hardware::camera2::ICameraDeviceCallbacks*>(cameraCb.get());
*client = new CameraDeviceClient(cameraService, tmp, packageName, cameraId,
facing, clientPid, clientUid, servicePid);
}
break;
default:
// Should not be reachable
ALOGE("Unknown camera device HAL version: %d", deviceVersion);
return STATUS_ERROR_FMT(ERROR_INVALID_OPERATION,
"Camera device \"%s\" has unknown HAL version %d",
cameraId.string(), deviceVersion);
}
} else {
// A particular HAL version is requested by caller. Create CameraClient
// based on the requested HAL version.
if (deviceVersion > CAMERA_DEVICE_API_VERSION_1_0 &&
halVersion == CAMERA_DEVICE_API_VERSION_1_0) {
// Only support higher HAL version device opened as HAL1.0 device.
sp<ICameraClient> tmp = static_cast<ICameraClient*>(cameraCb.get());
*client = new CameraClient(cameraService, tmp, packageName, cameraIdToInt(cameraId),
facing, clientPid, clientUid, servicePid, legacyMode);
} else {
// Other combinations (e.g. HAL3.x open as HAL2.x) are not supported yet.
ALOGE("Invalid camera HAL version %x: HAL %x device can only be"
" opened as HAL %x device", halVersion, deviceVersion,
CAMERA_DEVICE_API_VERSION_1_0);
return STATUS_ERROR_FMT(ERROR_ILLEGAL_ARGUMENT,
"Camera device \"%s\" (HAL version %d) cannot be opened as HAL version %d",
cameraId.string(), deviceVersion, halVersion);
}
}
return Status::ok();
}
在此处有2 个关键步骤
步骤1：创建Camera 的客户端 Client，根据调用出可知是 CameraDeviceClient，创建时同时传入了一个Hal层回调的状态对象，为ICameraDeviceCallbacks 分别对应上面2个函数
makeClient 函数 会根据传入的HAL版本号halVersion 和设备版本号deviceVersion 进行初始化以及API的版本号，初始化了一个CamDeviceClien对象
查看构造函数发现初始化了父类Camera2ClientBase
CameraDeviceClient::CameraDeviceClient(const sp<CameraService>& cameraService,
const sp<hardware::camera2::ICameraDeviceCallbacks>& remoteCallback,
const String16& clientPackageName,
const String8& cameraId,
int cameraFacing,
int clientPid,
uid_t clientUid,
int servicePid) :
Camera2ClientBase(cameraService, remoteCallback, clientPackageName,
cameraId, cameraFacing, clientPid, clientUid, servicePid),
mInputStream(),
mStreamingRequestId(REQUEST_ID_NONE),
mRequestIdCounter(0) {
ATRACE_CALL();
ALOGI("CameraDeviceClient %s: Opened", cameraId.string());
}
继续查看最终发现是初始化了一个 Camera3Device对象，这个就是java APP
在打开 Cmaera 时真正创建的Frameowok 层对象，属于真正干活的
template <typename TClientBase>
Camera2ClientBase<TClientBase>::Camera2ClientBase(
const sp<CameraService>& cameraService,
const sp<TCamCallbacks>& remoteCallback,
const String16& clientPackageName,
const String8& cameraId,
int cameraFacing,
int clientPid,
uid_t clientUid,
int servicePid):
TClientBase(cameraService, remoteCallback, clientPackageName,
cameraId, cameraFacing, clientPid, clientUid, servicePid),
mSharedCameraCallbacks(remoteCallback),
mDeviceVersion(cameraService->getDeviceVersion(TClientBase::mCameraIdStr)),
mDeviceActive(false)
{
ALOGI("Camera %s: Opened. Client: %s (PID %d, UID %d)", cameraId.string(),
String8(clientPackageName).string(), clientPid, clientUid);
mInitialClientPid = clientPid;
mDevice = new Camera3Device(cameraId);
LOG_ALWAYS_FATAL_IF(mDevice == 0, "Device should never be NULL here.");
}
步骤二：
对此CameraDeviceClient 进行初始化，初始化的时候传入了mCameraProviderManager，即
client = static_cast<CLIENT*>(tmp.get());
ALOGI("%s(), make client for '%s'.", __FUNCTION__, String8{clientPackageName}.string());
LOG_ALWAYS_FATAL_IF(client.get() == nullptr, "%s: CameraService in invalid state",
__FUNCTION__);
err = client->initialize(mCameraProviderManager);
sp<CameraProviderManager> mCameraProviderManager，此对象在CameraService 初始化的时候就构造出来了，主要工作之一也是连接HAI层
mCameraProviderManager 是CameraServics 构造函数初始化的时候赋值的
if (nullptr == mCameraProviderManager.get()) {
mCameraProviderManager = new CameraProviderManager();
res = mCameraProviderManager->initialize(this);
if (res != OK) {
ALOGE("%s: Unable to initialize camera provider manager: %s (%d)",
__FUNCTION__, strerror(-res), res);
return res;
}
}
3：通知APP层Camera状态
frameworks\base\core\java\android\hardware\camera2\impl\CameraDeviceImpl.java
通知到APP Camera 已经打开，即在nataive 创建了CameraClient 完成之后CameraManager将native camera device设到java 的CameraDevice 之后即通知了APP，Camera创建好了
deviceImpl.setRemoteDevice(cameraUser);
device = deviceImpl;
/**
* Set remote device, which triggers initial onOpened/onUnconfigured callbacks
*
* <p>This function may post onDisconnected and throw CAMERA_DISCONNECTED if remoteDevice dies
* during setup.</p>
*
*/
public void setRemoteDevice(ICameraDeviceUser remoteDevice) throws CameraAccessException {
synchronized(mInterfaceLock) {
// TODO: Move from decorator to direct binder-mediated exceptions
// If setRemoteFailure already called, do nothing
if (mInError) return;
mRemoteDevice = new ICameraDeviceUserWrapper(remoteDevice);
IBinder remoteDeviceBinder = remoteDevice.asBinder();
// For legacy camera device, remoteDevice is in the same process, and
// asBinder returns NULL.
if (remoteDeviceBinder != null) {
try {
remoteDeviceBinder.linkToDeath(this, /*flag*/ 0);
} catch (RemoteException e) {
CameraDeviceImpl.this.mDeviceHandler.post(mCallOnDisconnected);
throw new CameraAccessException(CameraAccessException.CAMERA_DISCONNECTED,
"The camera device has encountered a serious error");
}
}
mDeviceHandler.post(mCallOnOpened);
mDeviceHandler.post(mCallOnUnconfigured);
}
}
private final Runnable mCallOnOpened = new Runnable() {
@Override
public void run() {
StateCallbackKK sessionCallback = null;
synchronized(mInterfaceLock) {
if (mRemoteDevice == null) return; // Camera already closed
sessionCallback = mSessionStateCallback;
}
if (sessionCallback != null) {
sessionCallback.onOpened(CameraDeviceImpl.this);
}
mDeviceCallback.onOpened(CameraDeviceImpl.this);
}
};
此处是在App层定义了AIDL 接口，但是服务是native层的，为了双方能通信，Aidl的调用客户端是使用java 实现，服务端采用c++实现的，确保了binder通信正常，此处用到的Binder服务关键函数为
connectDevice，因此connectDevice 的通信方式再此跟踪下：
frameworks\av\camera\aidl\android\hardware\ICameraService.aidl
/**
* Open a camera device through the new camera API
* Only supported for device HAL versions >= 3.2
*/
ICameraDeviceUser connectDevice(ICameraDeviceCallbacks callbacks,
String cameraId,
String opPackageName,
int clientUid);
aidl_java.png
aidl_java2.png
服务端实现此函数收到函数请求，如下：
class BpCameraService : public ::android::BpInterface<ICameraService> {
public:
explicit BpCameraService(const ::android::sp<::android::IBinder>& _aidl_impl);
virtual ~BpCameraService() = default;
::android::binder::Status getNumberOfCameras(int32_t type, int32_t* _aidl_return) override;
::android::binder::Status getCameraInfo(int32_t cameraId, ::android::hardware::CameraInfo* _aidl_return) override;
::android::binder::Status connect(const ::android::sp<::android::hardware::ICameraClient>& client, int32_t cameraId, const ::android::String16& opPackageName, int32_t cl
::android::binder::Status connectDevice(const ::android::sp<::android::hardware::camera2::ICameraDeviceCallbacks>& callbacks, const ::android::String16& cameraId, const
::android::binder::Status connectLegacy(const ::android::sp<::android::hardware::ICameraClient>& client, int32_t cameraId, int32_t halVersion, const ::android::String16&
::android::binder::Status addListener(const ::android::sp<::android::hardware::ICameraServiceListener>& listener, ::std::vector<::android::hardware::CameraStatus>* _aidl
::android::binder::Status removeListener(const ::android::sp<::android::hardware::ICameraServiceListener>& listener) override;
::android::binder::Status getCameraCharacteristics(const ::android::String16& cameraId, ::android::hardware::camera2::impl::CameraMetadataNative* _aidl_return) override;
::android::binder::Status getCameraVendorTagDescriptor(::android::hardware::camera2::params::VendorTagDescriptor* _aidl_return) override;
::android::binder::Status getCameraVendorTagCache(::android::hardware::camera2::params::VendorTagDescriptorCache* _aidl_return) override;
::android::binder::Status getLegacyParameters(int32_t cameraId, ::android::String16* _aidl_return) override;
::android::binder::Status supportsCameraApi(const ::android::String16& cameraId, int32_t apiVersion, bool* _aidl_return) override;
::android::binder::Status setTorchMode(const ::android::String16& cameraId, bool enabled, const ::android::sp<::android::IBinder>& clientBinder) override;
::android::binder::Status notifySystemEvent(int32_t eventId, const ::std::vector<int32_t>& args) override;
}; // class BpCameraService
}
services2.png
Status CameraService::connectDevice(
const sp<hardware::camera2::ICameraDeviceCallbacks>& cameraCb,
const String16& cameraId,
const String16& clientPackageName,
int clientUid,
/*out*/
sp<hardware::camera2::ICameraDeviceUser>* device) {
ATRACE_CALL();
Status ret = Status::ok();
String8 id = String8(cameraId);
sp<CameraDeviceClient> client = nullptr;
ret = connectHelper<hardware::camera2::ICameraDeviceCallbacks,CameraDeviceClient>(cameraCb, id,
CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageName,
clientUid, USE_CALLING_PID, API_2,
/*legacyMode*/ false, /*shimUpdateOnly*/ false,
/*out*/client);
if(!ret.isOk()) {
logRejected(id, getCallingPid(), String8(clientPackageName),
ret.toString8());
return ret;
}
String8 pid = String8::format("%d", getCallingPid());
POWERPUSH(129, clientName8.string(), id.string(), pid.string());//define in LogPower.java, 129 stand for camera start now
*device = client;
//add for send msg to nfc
char needSendMsg[255];
property_get("ro.config.hw_camera_nfc_switch",needSendMsg,"");
ALOGI("NFC polling %s", needSendMsg);
if (0 == strcmp(needSendMsg, "true")) {
String8 isOpen = String8::format("false");
android::allowNfcPolling(isOpen);
}
ALOGI("%s(), exit.", __FUNCTION__);
return ret;
}
简单捋顺下调用过程：
CameraManager.Java的connectDevice ICameraService.java(系统编译)的onTransact-
ICameraService.cpp(系统编译)的BpCameraService::connectDevice()ICameraService.cpp(系统编译)的::android::status_t BnCameraService::onTransact-
CameraService.cpp的CameraService::connectDevice()
APP 进程在打开之后就等待nataive 层运行结束，native层直到上节分析的创建成功
CameraDevice对象之后由CameraManager进行给java层的CameraDeviceIml 设置
setRemoteDevice，APP进程打开设备成功，得到了framework给到的CameraDeviceIml对象，可以后续通过此对Camera进行操作
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