Camera Open 流程源码分析
程序员Android
共 13633字，需浏览 28分钟
· 2020-11-27
和你一起终身学习，这里是程序员Android
经典好文推荐，通过阅读本文，您将收获以下知识点:
1.app层 MainActivity.java CameraManager 可以直接调用 其openCamera 方法
getCameraIdList 用来存储可用Camera设备 list， openCamera 成功后会调用CameraDevice.StateCallback#onOpened，
然后会创建Session CameraDevice#createCaptureSession 以及拍照CameraDevice#createCaptureRequest等等。
public class MainActivity extends AppCompatActivity {
protected void onCreate(@Nullable Bundle savedInstanceState) {
... ...
//
CameraManager mCameraManager.openCamera(mCameraId, mStateCallback, mBackgroundHandler);
... ...
}
2.CameraManager.java
(frameworks\base\core\java\android\hardware\camera2)
CameraManager 会根据传递过来的参数不同，调用不同的Opencamera 方法。
@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);
}
// CameraDeviceImpl.checkAndWrapHandler 会将 Handler 封装成Executor 类型
public static Executor checkAndWrapHandler(Handler handler) {
return new CameraHandlerExecutor(checkHandler(handler));
}
@RequiresPermission(android.Manifest.permission.CAMERA)
public void openCamera(@NonNull String cameraId,
@NonNull @CallbackExecutor Executor executor,
@NonNull final CameraDevice.StateCallback callback)
throws CameraAccessException {
openCameraForUid(cameraId, callback, executor, USE_CALLING_UID);
}
从代码中看，openCamera 参数主要区别是 CallbackExecutor 、Handler 这两个，最终都会走到 openCameraForUid 方法。
openCameraForUid 主要是 根据 Camera id 打开一个Camera 连接。
public void openCameraForUid(@NonNull String cameraId,
@NonNull final CameraDevice.StateCallback callback, @NonNull Executor executor,
int clientUid)
throws CameraAccessException {
//
openCameraDeviceUserAsync(cameraId, callback, executor, clientUid);
}
openCameraForUid 会调用 openCameraDeviceUserAsync 方法去帮助opencamera 连接的创建
private CameraDevice openCameraDeviceUserAsync(String cameraId,
CameraDevice.StateCallback callback, Executor executor, final int uid)
throws CameraAccessException {
// 获取 特定camera的特性
CameraCharacteristics characteristics = getCameraCharacteristics(cameraId);
android.hardware.camera2.impl.CameraDeviceImpl deviceImpl = new CameraDeviceImpl();
ICameraDeviceCallbacks callbacks = deviceImpl.getCallbacks()
if (supportsCamera2ApiLocked(cameraId)) {
// Use cameraservice's cameradeviceclient implementation for HAL3.2+ devices
ICameraService cameraService = CameraManagerGlobal.get().getCameraService();
cameraService.connectDevice(callbacks, cameraId,mContext.getOpPackageName(), uid);
}else{
... ...
}
// 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);
}
cameraService是通过Binder 继承 ICameraServiceListener.Stub
private static final class CameraManagerGlobal extends ICameraServiceListener.Stub
implements IBinder.DeathRecipient {
// This must match the ICameraService definition
private static final String CAMERA_SERVICE_BINDER_NAME = "media.camera";
public ICameraService getCameraService() {
synchronized(mLock) {
//
connectCameraServiceLocked();
return mCameraService;
}
}
private void connectCameraServiceLocked() {
IBinder cameraServiceBinder = ServiceManager.getService(CAMERA_SERVICE_BINDER_NAME);
ICameraService cameraService = ICameraService.Stub.asInterface(cameraServiceBinder);
for (CameraStatus c : cameraStatuses) {
onStatusChangedLocked(c.status, c.cameraId);
}
mCameraService = cameraService;
}
}
3.CameraService.cpp
(frameworks\av\services\camera\libcameraservice)
cameraService.connectDevice 通过AIDL 到用到 CameraService.cpp 中的connectDevice 方法。
Status CameraService::connectDevice(
const sp<hardware::camera2::ICameraDeviceCallbacks>& cameraCb,
const String16& cameraId,
const String16& clientPackageName,
int clientUid,
/*out*/
sp<hardware::camera2::ICameraDeviceUser>* device) {
//调用connectHelper 方法
ret = connectHelper<hardware::camera2::ICameraDeviceCallbacks,CameraDeviceClient>(cameraCb, id,
/*api1CameraId*/-1,
CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageNameAdj,
clientUid, USE_CALLING_PID, API_2, /*shimUpdateOnly*/ false, /*out*/client);
}
connectDevice 会调用到 connectHelper 方法
Status CameraService::connectHelper(){
// 闪光灯进入预准备阶段
mFlashlight->prepareDeviceOpen(cameraId);
//获取当前设备的Version
int deviceVersion = getDeviceVersion(cameraId, /*out*/&facing);
// 初始化CameraproviderManager
err = client->initialize(mCameraProviderManager, mMonitorTags);
}
4.CameraProviderManager.cpp
(frameworks\av\services\camera\libcameraservice\common)
status_t CameraProviderManager::initialize(wp<CameraProviderManager::StatusListener> listener,
ServiceInteractionProxy* proxy) {
// 调用 addProviderLocked 方法
for (const auto& instance : mServiceProxy->listServices()) {
this->addProviderLocked(instance);
}
}
status_t CameraProviderManager::addProviderLocked(const std::string& newProvider) {
sp<ProviderInfo> providerInfo = new ProviderInfo(newProvider, this);
status_t res = providerInfo->initialize(interface, mDeviceState);
}
//ProviderInfo::initialize 初始化方法
status_t CameraProviderManager::ProviderInfo::initialize(){
status_t res = addDevice(device, common::V1_0::CameraDeviceStatus::PRESENT, &id);
}
status_t CameraProviderManager::ProviderInfo::addDevice(const std::string& name,
CameraDeviceStatus initialStatus, /*out*/ std::string* parsedId) {
//
deviceInfo = initializeDeviceInfo<DeviceInfo3>(name, mProviderTagid,
id, minor);
}
std::unique_ptr<CameraProviderManager::ProviderInfo::DeviceInfo>
CameraProviderManager::ProviderInfo::initializeDeviceInfo(){
// 后续调用待完善 如何 跳转到 Camera3device.cpp 的initialize 方法
return std::unique_ptr<DeviceInfo>(
new DeviceInfoT(name, tagId, id, minorVersion, resourceCost, this,
mProviderPublicCameraIds, cameraInterface));
}
5.Camera3Device.cpp
(frameworks\av\services\camera\libcameraservice\device3)
status_t Camera3Device::initialize(sp<CameraProviderManager> manager, const String8& monitorTags) {
// 调用 CameraProviderManager openSession
ATRACE_BEGIN("CameraHal::openSession");
status_t res = manager->openSession(mId.string(), this,
/*out*/ &session);
ATRACE_END();
return initializeCommonLocked();
}
6.CameraProviderManager.cpp
(frameworks\av\services\camera\libcameraservice\common)
status_t CameraProviderManager::openSession(const std::string &id,
const sp<device::V3_2::ICameraDeviceCallback>& callback,
/*out*/
sp<device::V3_2::ICameraDeviceSession> *session) {
auto interface = deviceInfo3->startDeviceInterface<
CameraProviderManager::ProviderInfo::DeviceInfo3::InterfaceT>();
ret = interface->open(callback, [&status, &session]
(Status s, const sp<device::V3_2::ICameraDeviceSession>& cameraSession) {
status = s;
if (status == Status::OK) {
*session = cameraSession;
}
});
}
7.ICameraDevice.hal
(hardware\interfaces\camera\device\3.2)
//Power on and initialize this camera device for active use, returning a
//session handle for active operations.
open(ICameraDeviceCallback callback) generates
(Status status, ICameraDeviceSession session);
8.CameraDevice.cpp
(hardware\interfaces\camera\device\3.2\default)
Return<void> CameraDevice::open(const sp<ICameraDeviceCallback>& callback,
ICameraDevice::open_cb _hidl_cb) {
/** Open HAL device */
status_t res;
camera3_device_t *device;
// 1. 开始 open Hal Device
ATRACE_BEGIN("camera3->open");
res = mModule->open(mCameraId.c_str(),
reinterpret_cast<hw_device_t**>(&device));
ATRACE_END();
// 2. 获取Camera 信息
res = mModule->getCameraInfo(mCameraIdInt, &info);
// 3. 创建 CameraDeviceSession
session = createSession(device, info.static_camera_characteristics, callback);
}
CameraModule.cpp
(hardware\interfaces\camera\common\1.0\default)
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;
}
10.Camxhal3entry.cpp
(vendor\qcom\proprietary\camx\src\core\hal)
int open(
const struct hw_module_t* pHwModuleAPI,
const char* pCameraIdAPI,
struct hw_device_t** ppHwDeviceAPI)
{
/// @todo (CAMX-43) - Reload Jumptable from settings
JumpTableHAL3* pHAL3 = static_cast<JumpTableHAL3*>(g_dispatchHAL3.GetJumpTable());
return pHAL3->open(pHwModuleAPI, pCameraIdAPI, ppHwDeviceAPI);
}
11.Camxhal3.cpp
(vendor\qcom\proprietary\camx\src\core\hal)
static int open(){
// 检查CameraId 是否有效
cameraId = OsUtils::StrToUL(pCameraIdAPI, &pNameEnd, 10);
// 检查闪光灯状态，如果 on 状态，需要off
HAL3Module::GetInstance()->ReserveTorchForCamera(
GetCHIAppCallbacks()->chi_remap_camera_id(cameraId, IdRemapTorch), cameraId);
// 调用 Camxhal3module ProcessCameraOpen 方法
result = HAL3Module::GetInstance()->ProcessCameraOpen(logicalCameraId, &extend);
// 创建HalDevice 实例并初始化
pHALDevice = HALDevice::Create(pHwModule, logicalCameraId, cameraId);
}
12.Camxhal3module.cpp
(vendor\qcom\proprietary\camx\src\core\hal)
CamxResult HAL3Module::ProcessCameraOpen(){
result = m_ChiAppCallbacks.chi_extend_open(logicalCameraId, pPriv);
}
13.Chxextensioninterface.cpp
(vendor\qcom\proprietary\chi-cdk\core\chiframework)
static CDKResult chi_extend_open(){
ExtensionModule* pExtensionModule = ExtensionModule::GetInstance();
CHX_LOG_DEBUG("[OP_EXT] OPEN_CAMERA E cameraId %d", cameraId);
CDKResult result = pExtensionModule->ExtendOpen(cameraId, priv);
CHX_LOG_DEBUG("[OP_EXT] OPEN_CAMERA X");
}
14.Chxextensionmodule.cpp
(vendor\qcom\proprietary\chi-cdk\core\chiframework)
CDKResult ExtensionModule::ExtendOpen(){
// 调用 Perflock 提高 opencamera 性能
m_pPerfLockManager[logicalCameraId] = PerfLockManager::Create();
if (PERF_LOCK_OPEN_CAMERA != m_previousPowerHint)
{
m_pPerfLockManager[logicalCameraId]->ReleasePerfLock(m_previousPowerHint);
m_pPerfLockManager[logicalCameraId]->AcquirePerfLock(PERF_LOCK_OPEN_CAMERA, 10000);
m_previousPowerHint = PERF_LOCK_OPEN_CAMERA;
}
// open 结束返回到 camxhal3.cpp
}
15.Camxhal3.cpp
(vendor\qcom\proprietary\camx\src\core\hal)
static int open(){
// 检查CameraId 是否有效
cameraId = OsUtils::StrToUL(pCameraIdAPI, &pNameEnd, 10);
// 检查闪光灯状态，如果 on 状态，需要off
HAL3Module::GetInstance()->ReserveTorchForCamera(
GetCHIAppCallbacks()->chi_remap_camera_id(cameraId, IdRemapTorch), cameraId);
// 调用 Camxhal3module ProcessCameraOpen 方法
result = HAL3Module::GetInstance()->ProcessCameraOpen(logicalCameraId, &extend);
// 创建HalDevice 实例并初始化
pHALDevice = HALDevice::Create(pHwModule, logicalCameraId, cameraId);
}
16.Camxhaldevice.cpp
(vendor\qcom\proprietary\camx\src\core\hal)
HALDevice* HALDevice::Create(){
result = pHALDevice->Initialize(pHwModule, cameraId);
}
CamxResult HALDevice::Initialize(){
... ...
// 初始化完成后，需要返回 CameraDevice.cpp 中继续执行 open 中的方法
}
17.CameraDevice.cpp
(hardware\interfaces\camera\device\3.2\default)
Return<void> CameraDevice::open(const sp<ICameraDeviceCallback>& callback,
ICameraDevice::open_cb _hidl_cb) {
/** Open HAL device */
status_t res;
camera3_device_t *device;
// 1. 开始 open Hal Device
ATRACE_BEGIN("camera3->open");
res = mModule->open(mCameraId.c_str(),
reinterpret_cast<hw_device_t**>(&device));
ATRACE_END();
// 2. 获取Camera 信息
res = mModule->getCameraInfo(mCameraIdInt, &info);
// 3. 创建 CameraDeviceSession
session = createSession(device, info.static_camera_characteristics, callback);
}
//3. 创建 CameraDeviceSession 方法实现
sp<CameraDeviceSession> CameraDevice::createSession(camera3_device_t* device,
const camera_metadata_t* deviceInfo,
const sp<ICameraDeviceCallback>& callback) {
return new CameraDeviceSession(device, deviceInfo, callback);
}
18.CameraDeviceSession.cpp
(hardware\interfaces\camera\device\3.2\default) 62313 2020/8/11
CameraDeviceSession::CameraDeviceSession(){
//调用 initialize 方法
mInitFail = initialize();
}
bool CameraDeviceSession::initialize() {
// 初始化完成之后返回 CameraProviderManager
}
CamxOpen流程（参考网络）
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