[移动开发]Camera framework/HAL（二）

接着上一遍文章，我们将理解CameraService的获取与构造。

CameraService的启动：

av/camera/cameraserver/Android.bp

->av/camera/cameraserver/cameraserver.rc

->av/camera/cameraserver/main_cameraserver.cpp

• Andorid.mk将cameraserver.rc打包到system/etc/init目录下，并指定源代码为main_cameraserver.cpp；
• Android架构启动时启动init.rc进程，启动了位于system/etc/init目录下的cameraserver.rc。值得一提的是，同时也会启动zygote进程（第一个Java层进程，也是Java层所有进程的父进程）、ServiceManager、mediaserver（多媒体服务进程，Android7.0之前cameraserver属于mediaserver，和mediaserver位于同一进程）、surfaceflinger（屏幕渲染相关的进程）等。之后zygote会孵化出启动system_server进程，Android framework里面的所有service（ActivityManagerService、WindowManagerService等）都是由system_server启动。关于system_server启动暂不讲述。
• 启动cameraserver.rc时，执行main_cameraserver.cpp中的main方法，通过CameraServe::instantiaicte()初始化CameraService

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OpenCamera中使用CameraService.

如何传递到CameraService.cpp中

base/core/java/android/hardware/camera2/CameraManager.java

connectDevice->

av/camera/aidl/android/hardware/ICameraService.aidl

connectDevice->

av/services/camera/libcameraservice/hidl/HidlCameraService.cpp

connectDevice->

av/services/camera/libcameraservice/CameraService.cpp

connectDevice->

    ret = connectHelper<hardware::camera2::ICameraDeviceCallbacks,CameraDeviceClient>(cameraCb, id,
            /*api1CameraId*/-1,
            CAMERA_HAL_API_VERSION_UNSPECIFIED, clientPackageNameAdj, clientFeatureId,
            clientUid, USE_CALLING_PID, API_2, /*shimUpdateOnly*/ false, /*out*/client);

cameraCb;ICameraDeviceCallbacks
clientPackageNameAdj:getOpPackageName包名
id:cameraId
client:CameraDeviceClient

//此处传入参数mCameraProviderManager暂未分析，

        if(!(ret = makeClient(this, cameraCb, clientPackageName, clientFeatureId,
                cameraId, api1CameraId, facing,
                clientPid, clientUid, getpid(),
                halVersion, deviceVersion, effectiveApiLevel,
                /*out*/&tmp)).isOk()) {
            return ret;
        }

....
        err = client->initialize(mCameraProviderManager, mMonitorTags);

makeClient:

            else { // Camera2 API route
                sp<hardware::camera2::ICameraDeviceCallbacks> tmp =
                        static_cast<hardware::camera2::ICameraDeviceCallbacks*>(cameraCb.get());
                *client = new CameraDeviceClient(cameraService, tmp, packageName, featureId,
                        cameraId, facing, clientPid, clientUid, servicePid);
            }

ICameraDeviceCallbacks

CameraDeviceClient

CameraDeviceClient->Camera2ClientBase->

CameraDeviceClient::CameraDeviceClient(const sp<CameraService>& cameraService,
        const sp<hardware::camera2::ICameraDeviceCallbacks>& remoteCallback,//回调函数
        const String16& clientPackageName,
        const std::unique_ptr<String16>& clientFeatureId,
        const String8& cameraId,
        int cameraFacing,
        int clientPid,
        uid_t clientUid,
        int servicePid) :
    Camera2ClientBase(cameraService, remoteCallback, clientPackageName, clientFeatureId,
                cameraId, /*API1 camera ID*/ -1,
                cameraFacing, clientPid, clientUid, servicePid),
    mInputStream(),
    mStreamingRequestId(REQUEST_ID_NONE),
    mRequestIdCounter(0) {

    ATRACE_CALL();
    ALOGI("CameraDeviceClient %s: Opened", cameraId.string());
}


template <typename TClientBase>
Camera2ClientBase<TClientBase>::Camera2ClientBase(
        const sp<CameraService>& cameraService,
        const sp<TCamCallbacks>& remoteCallback,
        const String16& clientPackageName,
        const std::unique_ptr<String16>& clientFeatureId,
        const String8& cameraId,
        int api1CameraId,
        int cameraFacing,
        int clientPid,
        uid_t clientUid,
        int servicePid):
        TClientBase(cameraService, remoteCallback, clientPackageName, clientFeatureId,
                cameraId, api1CameraId, cameraFacing, clientPid, clientUid, servicePid),
        mSharedCameraCallbacks(remoteCallback),
        mDeviceVersion(cameraService->getDeviceVersion(TClientBase::mCameraIdStr)),
        mDevice(new Camera3Device(cameraId)),
        mDeviceActive(false), mApi1CameraId(api1CameraId)
{
    ALOGI("Camera %s: Opened. Client: %s (PID %d, UID %d)", cameraId.string(),
            String8(clientPackageName).string(), clientPid, clientUid);

    mInitialClientPid = clientPid;
    LOG_ALWAYS_FATAL_IF(mDevice == 0, "Device should never be NULL here.");
}

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