Android P Camera2相机简单解析（一、openCamera）
openCamera
CameraManager
文件路径：/frameworks/base/core/java/android/hardware/camera2/CameraManager.java
上层调用的API有两个，分别如下：
@RequiresPermission(android.Manifest.permission.CAMERA)
public void openCamera(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @Nullable Handler handler)
throws CameraAccessException {
openCameraForUid(cameraId, callback, CameraDeviceImpl.checkAndWrapHandler(handler),
USE_CALLING_UID);
}
@RequiresPermission(android.Manifest.permission.CAMERA)
public void openCamera(@NonNull String cameraId,
@NonNull @CallbackExecutor Executor executor,
@NonNull final CameraDevice.StateCallback callback)
throws CameraAccessException {
if (executor == null) {
throw new IllegalArgumentException("executor was null");
}
openCameraForUid(cameraId, callback, executor, USE_CALLING_UID);
}
但是两种实际都是调用了 openCameraForUid(cameraId, callback, executor, USE_CALLING_UID)这个方法，这个方法实际上也是在此文件中，具体实现如下：
public void openCameraForUid(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @NonNull Executor executor,
int clientUid)
throws CameraAccessException {
if (cameraId == null) {
throw new IllegalArgumentException("cameraId was null");
} else if (callback == null) {
throw new IllegalArgumentException("callback was null");
}
if (CameraManagerGlobal.sCameraServiceDisabled) {
throw new IllegalArgumentException("No cameras available on device");
}
openCameraDeviceUserAsync(cameraId, callback, executor, clientUid);
}
这里做了容错性判断，紧接着调用了 openCameraDeviceUserAsync(cameraId, callback, executor, clientUid)，此方法也是在当前文件中，实现如下：
private CameraDevice openCameraDeviceUserAsync(String cameraId,
CameraDevice.StateCallback callback, Executor executor, 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,
executor,
characteristics,
mContext.getApplicationInfo().targetSdkVersion);
ICameraDeviceCallbacks callbacks = deviceImpl.getCallbacks();
try {
if (supportsCamera2ApiLocked(cameraId)) {
// Use cameraservice's cameradeviceclient implementation for HAL3.2+ devices
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;
}
这里主要关注上面的代码不仅仅23-31行中的cameraService.connectDevice，这仅仅是Connect到我们的Camera设备，并不能打开我们的Camera，所以第9行的ICameraDeviceUser cameraUser = null和第82行的deviceImpl.setRemoteDevice(cameraUser)也是非常重要的，这里对应了CameraDeviceImpl .java文件。但是这里我们还是先看cameraService.connectDevice实现，实际上是ICameraService.connectDevice，这里需要注意的是ICameraService实际上是aidl文件，也是就是说CameraManager通过通过 Binder 机制调用了 connectDevice 方法，这个connectDevice方法的实现在CameraService 中。
CameraService
文件路径：/frameworks/av/services/camera/libcameraservice/CameraService.cpp
代码如下：
Status CameraService::connectDevice(
const sp& cameraCb,
const String16& cameraId,
const String16& clientPackageName,
int clientUid,
/*out*/
sp* device) {
ATRACE_CALL();
Status ret = Status::ok();
String8 id = String8(cameraId);
sp client = nullptr;
ret = connectHelper(cameraCb, id,
/*api1CameraId*/-1,
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;
}
*device = client;
return ret;
}
不难发现这里第13行调用了connectHelper来实现连接相机的逻辑，具体代码如下：
Status CameraService::connectHelper(const sp& cameraCb, const String8& cameraId,
int api1CameraId, int halVersion, const String16& clientPackageName, int clientUid,
int clientPid, apiLevel effectiveApiLevel, bool legacyMode, bool shimUpdateOnly,
/*out*/sp& 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(effectiveApiLevel));
sp client = nullptr;
{
// Acquire mServiceLock and prevent other clients from connecting
std::unique_ptr 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 clientTmp = nullptr;
std::shared_ptr>> 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(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 tmp = nullptr;
if(!(ret = makeClient(this, cameraCb, clientPackageName,
cameraId, api1CameraId, facing,
clientPid, clientUid, getpid(), legacyMode,
halVersion, deviceVersion, effectiveApiLevel,
/*out*/&tmp)).isOk()) {
return ret;
}
client = static_cast(tmp.get());
LOG_ALWAYS_FATAL_IF(client.get() == nullptr, "%s: CameraService in invalid state",
__FUNCTION__);
err = client->initialize(mCameraProviderManager, mMonitorTags);
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 shimClient = reinterpret_cast(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
// Important: release the mutex here so the client can call back into the service from its
// destructor (can be at the end of the call)
device = client;
return ret;
}
在connectHelper中我们通过makeClient方法完成了client的生成并初始化，具体实现如下：
Status CameraService::makeClient(const sp& cameraService,
const sp& cameraCb, const String16& packageName, const String8& cameraId,
int api1CameraId, int facing, int clientPid, uid_t clientUid, int servicePid,
bool legacyMode, int halVersion, int deviceVersion, apiLevel effectiveApiLevel,
/*out*/sp* 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 tmp = static_cast(cameraCb.get());
*client = new CameraClient(cameraService, tmp, packageName,
api1CameraId, 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 tmp = static_cast(cameraCb.get());
*client = new Camera2Client(cameraService, tmp, packageName,
cameraId, api1CameraId,
facing, clientPid, clientUid,
servicePid, legacyMode);
} else { // Camera2 API route
sp tmp =
static_cast(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 tmp = static_cast(cameraCb.get());
*client = new CameraClient(cameraService, tmp, packageName,
api1CameraId, 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();
}
这一块儿基本就是根据API版本和Device版本来实例化Client的，在Android P 和Camera2的框架上，这里需要跟进的是38-39行，这里CameraDeviceClient方法是由CameraDeviceClient.cpp实现的。
CameraDeviceClient.cpp
文件路径：/frameworks/av/services/camera/libcameraservice/api2/CameraDeviceClient.cpp
CameraDeviceClient::CameraDeviceClient(const sp& cameraService,
const sp& remoteCallback,
const String16& clientPackageName,
const String8& cameraId,
int cameraFacing,
int clientPid,
uid_t clientUid,
int servicePid) :
Camera2ClientBase(cameraService, remoteCallback, clientPackageName,
cameraId, /*API1 camera ID*/ -1,
cameraFacing, clientPid, clientUid, servicePid),
mInputStream(),
mStreamingRequestId(REQUEST_ID_NONE),
mRequestIdCounter(0) {
ATRACE_CALL();
ALOGI("CameraDeviceClient %s: Opened", cameraId.string());
}
这里关注第9行，发现又调用了Camera2ClientBase方法，实现代码如下：
Camera2ClientBase::Camera2ClientBase(
const sp& cameraService,
const sp& remoteCallback,
const String16& clientPackageName,
const String8& cameraId,
int api1CameraId,
int cameraFacing,
int clientPid,
uid_t clientUid,
int servicePid):
TClientBase(cameraService, remoteCallback, clientPackageName,
cameraId, api1CameraId, cameraFacing, clientPid, clientUid, servicePid),
mSharedCameraCallbacks(remoteCallback),
mDeviceVersion(cameraService->getDeviceVersion(TClientBase::mCameraIdStr)),
mDeviceActive(false), mApi1CameraId(api1CameraId)
{
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.");
}
好吧，第21行mDevice = new Camera3Device(cameraId)才是重点，是由Camera3Device.cpp实现的。
Camera3Device.cpp
文件路径：/frameworks/av/services/camera/libcameraservice/device3/Camera3Device.cpp
Camera3Device::Camera3Device(const String8 &id):
mId(id),
mOperatingMode(NO_MODE),
mIsConstrainedHighSpeedConfiguration(false),
mStatus(STATUS_UNINITIALIZED),
mStatusWaiters(0),
mUsePartialResult(false),
mNumPartialResults(1),
mTimestampOffset(0),
mNextResultFrameNumber(0),
mNextReprocessResultFrameNumber(0),
mNextShutterFrameNumber(0),
mNextReprocessShutterFrameNumber(0),
mListener(NULL),
mVendorTagId(CAMERA_METADATA_INVALID_VENDOR_ID),
mLastTemplateId(-1)
{
ATRACE_CALL();
camera3_callback_ops::notify = &sNotify;
camera3_callback_ops::process_capture_result = &sProcessCaptureResult;
ALOGV("%s: Created device for camera %s", __FUNCTION__, mId.string());
}
到此CameraService.cpp中的makeClient工作就已经完成了并构造了"CameraDeviceClient"，接下来就是connectHelper中的client->initialize这块儿了，从上面分析我们知道这里的client 指的对象就是Camera3Device了，所以我们继续找到Camera3Device中的initialize方法，代码如下：
status_t Camera3Device::initialize(sp manager, const String8& monitorTags) {
ATRACE_CALL();
Mutex::Autolock il(mInterfaceLock);
Mutex::Autolock l(mLock);
ALOGV("%s: Initializing HIDL device for camera %s", __FUNCTION__, mId.string());
if (mStatus != STATUS_UNINITIALIZED) {
CLOGE("Already initialized!");
return INVALID_OPERATION;
}
if (manager == nullptr) return INVALID_OPERATION;
sp session;
ATRACE_BEGIN("CameraHal::openSession");
status_t res = manager->openSession(mId.string(), this,
/*out*/ &session);
ATRACE_END();
if (res != OK) {
SET_ERR_L("Could not open camera session: %s (%d)", strerror(-res), res);
return res;
}
res = manager->getCameraCharacteristics(mId.string(), &mDeviceInfo);
if (res != OK) {
SET_ERR_L("Could not retrive camera characteristics: %s (%d)", strerror(-res), res);
session->close();
return res;
}
std::shared_ptr queue;
auto requestQueueRet = session->getCaptureRequestMetadataQueue(
[&queue](const auto& descriptor) {
queue = std::make_shared(descriptor);
if (!queue->isValid() || queue->availableToWrite() <= 0) {
ALOGE("HAL returns empty request metadata fmq, not use it");
queue = nullptr;
// don't use the queue onwards.
}
});
if (!requestQueueRet.isOk()) {
ALOGE("Transaction error when getting request metadata fmq: %s, not use it",
requestQueueRet.description().c_str());
return DEAD_OBJECT;
}
std::unique_ptr& resQueue = mResultMetadataQueue;
auto resultQueueRet = session->getCaptureResultMetadataQueue(
[&resQueue](const auto& descriptor) {
resQueue = std::make_unique(descriptor);
if (!resQueue->isValid() || resQueue->availableToWrite() <= 0) {
ALOGE("HAL returns empty result metadata fmq, not use it");
resQueue = nullptr;
// Don't use the resQueue onwards.
}
});
if (!resultQueueRet.isOk()) {
ALOGE("Transaction error when getting result metadata queue from camera session: %s",
resultQueueRet.description().c_str());
return DEAD_OBJECT;
}
IF_ALOGV() {
session->interfaceChain([](
::android::hardware::hidl_vec<::android::hardware::hidl_string> interfaceChain) {
ALOGV("Session interface chain:");
for (auto iface : interfaceChain) {
ALOGV(" %s", iface.c_str());
}
});
}
mInterface = new HalInterface(session, queue); //新建硬件抽象层接口实例
std::string providerType;
mVendorTagId = manager->getProviderTagIdLocked(mId.string());
mTagMonitor.initialize(mVendorTagId);
if (!monitorTags.isEmpty()) {
mTagMonitor.parseTagsToMonitor(String8(monitorTags));
}
return initializeCommonLocked();
}
代码中第15行 res = manager->openSession 就是走向open的地方了，但是还是需要继续到一个方法，不难发现openSession方法由CameraProviderManager.cpp实现。此外在这里我们还需要注意第31和47行，第31行是请求队列，47行是结果队列在下一篇中将使用到。
CameraProviderManager.cpp
文件路径：***/frameworks/av/services/camera/libcameraservice/common/CameraProviderManager.cpp***
具体代码如下：
status_t CameraProviderManager::openSession(const std::string &id,
const sp& callback,
/*out*/
sp *session) {
std::lock_guard lock(mInterfaceMutex);
auto deviceInfo = findDeviceInfoLocked(id,
/*minVersion*/ {3,0}, /*maxVersion*/ {4,0});
if (deviceInfo == nullptr) return NAME_NOT_FOUND;
auto *deviceInfo3 = static_cast(deviceInfo);
Status status;
hardware::Return ret;
ret = deviceInfo3->mInterface->open(callback, [&status, &session]
(Status s, const sp& cameraSession) {
status = s;
if (status == Status::OK) {
*session = cameraSession;
}
});
if (!ret.isOk()) {
ALOGE("%s: Transaction error opening a session for camera device %s: %s",
__FUNCTION__, id.c_str(), ret.description().c_str());
return DEAD_OBJECT;
}
return mapToStatusT(status);
}
其中第16行ret = deviceInfo3->mInterface->open 实际上通过Hidl指向了CameraDevice::open()，该方法由CameraDevice.cpp实现。
CameraDevice.cpp
文件路径：***/hardware/interfaces/camera/device/3.2/default/CameraDevice.cpp***
代码如下：
Return CameraDevice::open(const sp& callback, open_cb _hidl_cb) {
Status status = initStatus();
sp session = nullptr;
if (callback == nullptr) {
ALOGE("%s: cannot open camera %s. callback is null!",
__FUNCTION__, mCameraId.c_str());
_hidl_cb(Status::ILLEGAL_ARGUMENT, nullptr);
return Void();
}
if (status != Status::OK) {
// Provider will never pass initFailed device to client, so
// this must be a disconnected camera
ALOGE("%s: cannot open camera %s. camera is disconnected!",
__FUNCTION__, mCameraId.c_str());
_hidl_cb(Status::CAMERA_DISCONNECTED, nullptr);
return Void();
} else {
mLock.lock();
ALOGV("%s: Initializing device for camera %d", __FUNCTION__, mCameraIdInt);
session = mSession.promote();
if (session != nullptr && !session->isClosed()) {
ALOGE("%s: cannot open an already opened camera!", __FUNCTION__);
mLock.unlock();
_hidl_cb(Status::CAMERA_IN_USE, nullptr);
return Void();
}
/** Open HAL device */
status_t res;
camera3_device_t *device;
ATRACE_BEGIN("camera3->open");
res = mModule->open(mCameraId.c_str(),
reinterpret_cast(&device));
ATRACE_END();
if (res != OK) {
ALOGE("%s: cannot open camera %s!", __FUNCTION__, mCameraId.c_str());
mLock.unlock();
_hidl_cb(getHidlStatus(res), nullptr);
return Void();
}
/** Cross-check device version */
if (device->common.version < CAMERA_DEVICE_API_VERSION_3_2) {
ALOGE("%s: Could not open camera: "
"Camera device should be at least %x, reports %x instead",
__FUNCTION__,
CAMERA_DEVICE_API_VERSION_3_2,
device->common.version);
device->common.close(&device->common);
mLock.unlock();
_hidl_cb(Status::ILLEGAL_ARGUMENT, nullptr);
return Void();
}
struct camera_info info;
res = mModule->getCameraInfo(mCameraIdInt, &info);
if (res != OK) {
ALOGE("%s: Could not open camera: getCameraInfo failed", __FUNCTION__);
device->common.close(&device->common);
mLock.unlock();
_hidl_cb(Status::ILLEGAL_ARGUMENT, nullptr);
return Void();
}
session = createSession(
device, info.static_camera_characteristics, callback);
if (session == nullptr) {
ALOGE("%s: camera device session allocation failed", __FUNCTION__);
mLock.unlock();
_hidl_cb(Status::INTERNAL_ERROR, nullptr);
return Void();
}
if (session->isInitFailed()) {
ALOGE("%s: camera device session init failed", __FUNCTION__);
session = nullptr;
mLock.unlock();
_hidl_cb(Status::INTERNAL_ERROR, nullptr);
return Void();
}
mSession = session;
IF_ALOGV() {
session->getInterface()->interfaceChain([](
::android::hardware::hidl_vec<::android::hardware::hidl_string> interfaceChain) {
ALOGV("Session interface chain:");
for (auto iface : interfaceChain) {
ALOGV(" %s", iface.c_str());
}
});
}
mLock.unlock();
}
_hidl_cb(status, session->getInterface());
return Void();
}
其中36-37行的res = mModule->open(mCameraId.c_str(), reinterpret_cast
CameraModule.cpp
文件路径：***/hardware/interfaces/camera/common/1.0/default/CameraModule.cpp***
代码如下：
int CameraModule::open(const char* id, struct hw_device_t** device) {
int res;
ATRACE_BEGIN("camera_module->open");
res = filterOpenErrorCode(mModule->common.methods->open(&mModule->common, id, device));
ATRACE_END();
return res;
}
不难发现，mModule->common.methods->open紧接着就是Hal层了，在这里我们需要先把Hal层启动流程弄清楚。在系统启动后，CameraService服务跑起来就是就会启动Hal层。
CameraService
文件路径：***/frameworks/av/services/camera/libcameraservice/CameraService.cpp***
代码如下：
void CameraService::onFirstRef()
{
ALOGI("CameraService process starting");
BnCameraService::onFirstRef();
// Update battery life tracking if service is restarting
BatteryNotifier& notifier(BatteryNotifier::getInstance());
notifier.noteResetCamera();
notifier.noteResetFlashlight();
status_t res = INVALID_OPERATION;
res = enumerateProviders();
if (res == OK) {
mInitialized = true;
}
CameraService::pingCameraServiceProxy();
mUidPolicy = new UidPolicy(this);
mUidPolicy->registerSelf();
}
这里第14行res = enumerateProviders()说明CameraService在初始化时，要先枚举Provider，实现代码如下：
status_t CameraService::enumerateProviders() {
status_t res;
std::vector deviceIds;
{
Mutex::Autolock l(mServiceLock);
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;
}
}
// Setup vendor tags before we call get_camera_info the first time
// because HAL might need to setup static vendor keys in get_camera_info
// TODO: maybe put this into CameraProviderManager::initialize()?
mCameraProviderManager->setUpVendorTags();
if (nullptr == mFlashlight.get()) {
mFlashlight = new CameraFlashlight(mCameraProviderManager, this);
}
res = mFlashlight->findFlashUnits();
if (res != OK) {
ALOGE("Failed to enumerate flash units: %s (%d)", strerror(-res), res);
}
deviceIds = mCameraProviderManager->getCameraDeviceIds();
}
for (auto& cameraId : deviceIds) {
String8 id8 = String8(cameraId.c_str());
onDeviceStatusChanged(id8, CameraDeviceStatus::PRESENT);
}
return OK;
}
这里又先初始化CameraProviderManager，并获取第三方厂家TAG，获取闪光灯，获取相机设备数，其中CameraProviderManager的初始化实现如下。
CameraProviderManager.cpp
文件路径：***/frameworks/av/services/camera/libcameraservice/common/CameraProviderManager.cpp***
具体代码如下：
status_t CameraProviderManager::initialize(wp listener,
ServiceInteractionProxy* proxy) {
std::lock_guard lock(mInterfaceMutex);
if (proxy == nullptr) {
ALOGE("%s: No valid service interaction proxy provided", __FUNCTION__);
return BAD_VALUE;
}
mListener = listener;
mServiceProxy = proxy;
// Registering will trigger notifications for all already-known providers
bool success = mServiceProxy->registerForNotifications(
/* instance name, empty means no filter */ "",
this);
if (!success) {
ALOGE("%s: Unable to register with hardware service manager for notifications "
"about camera providers", __FUNCTION__);
return INVALID_OPERATION;
}
// See if there's a passthrough HAL, but let's not complain if there's not
addProviderLocked(kLegacyProviderName, /*expected*/ false);
addProviderLocked(kExternalProviderName, /*expected*/ false);
return OK;
}
CameraProviderManager初始化中做的事情很明了，这里我们需要关注的是addProviderLocked这里进行查找并保存Provider，实现如下：
status_t CameraProviderManager::addProviderLocked(const std::string& newProvider, bool expected) {
for (const auto& providerInfo : mProviders) {
if (providerInfo->mProviderName == newProvider) {
ALOGW("%s: Camera provider HAL with name '%s' already registered", __FUNCTION__,
newProvider.c_str());
return ALREADY_EXISTS;
}
}
sp interface;
interface = mServiceProxy->getService(newProvider); //获取服务
if (interface == nullptr) {
if (expected) {
ALOGE("%s: Camera provider HAL '%s' is not actually available", __FUNCTION__,
newProvider.c_str());
return BAD_VALUE;
} else {
return OK;
}
}
sp providerInfo =
new ProviderInfo(newProvider, interface, this); //构建
status_t res = providerInfo->initialize(); //初始化
if (res != OK) {
return res;
}
mProviders.push_back(providerInfo); //备份
return OK;
}
这里需要关注 spprovider::V2_4::ICameraProvider interface这里的interface，最终指向了CameraProvider.cpp,不过我们需要先关注上面的构建和初始化providerInfo->initialize()，代码如下：
status_t CameraProviderManager::ProviderInfo::initialize() {
status_t res = parseProviderName(mProviderName, &mType, &mId);
if (res != OK) {
ALOGE("%s: Invalid provider name, ignoring", __FUNCTION__);
return BAD_VALUE;
}
ALOGI("Connecting to new camera provider: %s, isRemote? %d",
mProviderName.c_str(), mInterface->isRemote());
// cameraDeviceStatusChange callbacks may be called (and causing new devices added)
// before setCallback returns
hardware::Return status = mInterface->setCallback(this);
if (!status.isOk()) {
ALOGE("%s: Transaction error setting up callbacks with camera provider '%s': %s",
__FUNCTION__, mProviderName.c_str(), status.description().c_str());
return DEAD_OBJECT;
}
if (status != Status::OK) {
ALOGE("%s: Unable to register callbacks with camera provider '%s'",
__FUNCTION__, mProviderName.c_str());
return mapToStatusT(status);
}
hardware::Return linked = mInterface->linkToDeath(this, /*cookie*/ mId);
if (!linked.isOk()) {
ALOGE("%s: Transaction error in linking to camera provider '%s' death: %s",
__FUNCTION__, mProviderName.c_str(), linked.description().c_str());
return DEAD_OBJECT;
} else if (!linked) {
ALOGW("%s: Unable to link to provider '%s' death notifications",
__FUNCTION__, mProviderName.c_str());
}
// Get initial list of camera devices, if any
std::vector devices;
hardware::Return ret = mInterface->getCameraIdList([&status, &devices](
Status idStatus,
const hardware::hidl_vec& cameraDeviceNames) {
status = idStatus;
if (status == Status::OK) {
for (size_t i = 0; i < cameraDeviceNames.size(); i++) {
devices.push_back(cameraDeviceNames[i]);
}
} });
if (!ret.isOk()) {
ALOGE("%s: Transaction error in getting camera ID list from provider '%s': %s",
__FUNCTION__, mProviderName.c_str(), linked.description().c_str());
return DEAD_OBJECT;
}
if (status != Status::OK) {
ALOGE("%s: Unable to query for camera devices from provider '%s'",
__FUNCTION__, mProviderName.c_str());
return mapToStatusT(status);
}
sp listener = mManager->getStatusListener();
for (auto& device : devices) {
std::string id;
status_t res = addDevice(device,
hardware::camera::common::V1_0::CameraDeviceStatus::PRESENT, &id);//添加device
if (res != OK) {
ALOGE("%s: Unable to enumerate camera device '%s': %s (%d)",
__FUNCTION__, device.c_str(), strerror(-res), res);
continue;
}
}
ALOGI("Camera provider %s ready with %zu camera devices",
mProviderName.c_str(), mDevices.size());
mInitialized = true;
return OK;
}
这里主要关注上面的添加设备这块儿
status_t CameraProviderManager::ProviderInfo::addDevice(const std::string& name,
CameraDeviceStatus initialStatus, /*out*/ std::string* parsedId) {
ALOGI("Enumerating new camera device: %s", name.c_str());
uint16_t major, minor;
std::string type, id;
status_t res = parseDeviceName(name, &major, &minor, &type, &id);
if (res != OK) {
return res;
}
if (type != mType) {
ALOGE("%s: Device type %s does not match provider type %s", __FUNCTION__,
type.c_str(), mType.c_str());
return BAD_VALUE;
}
if (mManager->isValidDeviceLocked(id, major)) {
ALOGE("%s: Device %s: ID %s is already in use for device major version %d", __FUNCTION__,
name.c_str(), id.c_str(), major);
return BAD_VALUE;
}
std::unique_ptr deviceInfo;
switch (major) {
//实例化
case 1:
deviceInfo = initializeDeviceInfo(name, mProviderTagid,
id, minor);
break;
case 3:
deviceInfo = initializeDeviceInfo(name, mProviderTagid,
id, minor);
break;
default:
ALOGE("%s: Device %s: Unknown HIDL device HAL major version %d:", __FUNCTION__,
name.c_str(), major);
return BAD_VALUE;
}
if (deviceInfo == nullptr) return BAD_VALUE;
deviceInfo->mStatus = initialStatus;
bool isAPI1Compatible = deviceInfo->isAPI1Compatible();
mDevices.push_back(std::move(deviceInfo));
mUniqueCameraIds.insert(id);
if (isAPI1Compatible) {
mUniqueAPI1CompatibleCameraIds.push_back(id);
}
if (parsedId != nullptr) {
*parsedId = id;
}
return OK;
}
其中实例化device代码如下：
template
std::unique_ptr
CameraProviderManager::ProviderInfo::initializeDeviceInfo(
const std::string &name, const metadata_vendor_id_t tagId,
const std::string &id, uint16_t minorVersion) const {
Status status;
auto cameraInterface =
getDeviceInterface(name); //获取HAL层远程接口
if (cameraInterface == nullptr) return nullptr;
CameraResourceCost resourceCost;
cameraInterface->getResourceCost([&status, &resourceCost](
Status s, CameraResourceCost cost) {
status = s;
resourceCost = cost;
});
if (status != Status::OK) {
ALOGE("%s: Unable to obtain resource costs for camera device %s: %s", __FUNCTION__,
name.c_str(), statusToString(status));
return nullptr;
}
for (auto& conflictName : resourceCost.conflictingDevices) {
uint16_t major, minor;
std::string type, id;
status_t res = parseDeviceName(conflictName, &major, &minor, &type, &id);
if (res != OK) {
ALOGE("%s: Failed to parse conflicting device %s", __FUNCTION__, conflictName.c_str());
return nullptr;
}
conflictName = id;
}
return std::unique_ptr(
new DeviceInfoT(name, tagId, id, minorVersion, resourceCost,
cameraInterface));
}
其中获取HAL远程接口代码如下：
template<>
sp
CameraProviderManager::ProviderInfo::getDeviceInterface
(const std::string &name) const {
Status status;
sp cameraInterface;
hardware::Return ret;
ret = mInterface->getCameraDeviceInterface_V3_x(name, [&status, &cameraInterface](
Status s, sp interface) {
status = s;
cameraInterface = interface;
});
if (!ret.isOk()) {
ALOGE("%s: Transaction error trying to obtain interface for camera device %s: %s",
__FUNCTION__, name.c_str(), ret.description().c_str());
return nullptr;
}
if (status != Status::OK) {
ALOGE("%s: Unable to obtain interface for camera device %s: %s", __FUNCTION__,
name.c_str(), statusToString(status));
return nullptr;
}
return cameraInterface;
}
到了这里，可以看出ICameraDevice关联到了CameraDevice.cpp，那么providerInfo->initialize()就分析得差不多了，下面的就到了硬件层，回头来我们需要继续分析CameraProvider.cpp这里了，在这里就关注其初始化就可以了。
CameraProvider.cpp
文件路径：***/hardware/interfaces/camera/provider/2.4/default/CameraProvider.cpp***
代码如下：
bool CameraProvider::initialize() {
camera_module_t *rawModule;
int err = hw_get_module(CAMERA_HARDWARE_MODULE_ID,
(const hw_module_t **)&rawModule);
if (err < 0) {
ALOGE("Could not load camera HAL module: %d (%s)", err, strerror(-err));
return true;
}
mModule = new CameraModule(rawModule);
err = mModule->init();
if (err != OK) {
ALOGE("Could not initialize camera HAL module: %d (%s)", err, strerror(-err));
mModule.clear();
return true;
}
ALOGI("Loaded \"%s\" camera module", mModule->getModuleName());
// Setup vendor tags here so HAL can setup vendor keys in camera characteristics
VendorTagDescriptor::clearGlobalVendorTagDescriptor();
if (!setUpVendorTags()) {
ALOGE("%s: Vendor tag setup failed, will not be available.", __FUNCTION__);
}
// Setup callback now because we are going to try openLegacy next
err = mModule->setCallbacks(this);
if (err != OK) {
ALOGE("Could not set camera module callback: %d (%s)", err, strerror(-err));
mModule.clear();
return true;
}
mPreferredHal3MinorVersion =
property_get_int32("ro.vendor.camera.wrapper.hal3TrebleMinorVersion", 3);
ALOGV("Preferred HAL 3 minor version is %d", mPreferredHal3MinorVersion);
switch(mPreferredHal3MinorVersion) {
case 2:
case 3:
// OK
break;
default:
ALOGW("Unknown minor camera device HAL version %d in property "
"'camera.wrapper.hal3TrebleMinorVersion', defaulting to 3",
mPreferredHal3MinorVersion);
mPreferredHal3MinorVersion = 3;
}
mNumberOfLegacyCameras = mModule->getNumberOfCameras();
for (int i = 0; i < mNumberOfLegacyCameras; i++) {
struct camera_info info;
auto rc = mModule->getCameraInfo(i, &info);
if (rc != NO_ERROR) {
ALOGE("%s: Camera info query failed!", __func__);
mModule.clear();
return true;
}
if (checkCameraVersion(i, info) != OK) {
ALOGE("%s: Camera version check failed!", __func__);
mModule.clear();
return true;
}
char cameraId[kMaxCameraIdLen];
snprintf(cameraId, sizeof(cameraId), "%d", i);
std::string cameraIdStr(cameraId);
mCameraStatusMap[cameraIdStr] = CAMERA_DEVICE_STATUS_PRESENT;
addDeviceNames(i);
}
return false; // mInitFailed
}
这里就初始化了CameraMoudle。