Android Camera调用流程
16lz
2021-01-23
一个流程图画的非常好的文章
http://blog.csdn.net/lushengchu_luis/article/details/11033095
1、Packages/apps/到framework 打开Camera
- ./packages/apps/Camera/src/com/android/camera/Camera.java
进来第一个肯定是onCreate(Bundle icicle) {
这里是开始了一个Camera的线程
//start camera opening processmCameraStartUpThread = new CameraStartUpThread();CameraStarUpThread是一个类/// M: open camera process functions @{ private class CameraStartUpThread extends Thread { //上面的注释就写着open camera process functions 打开相机进程的函数 Util.openCamera(Camera.this, isPIPMode(getCurrentMode())); //这一句就是用Util这个类来打开相机进程了./packages/apps/Camera/src/com/android/camera/Util.java//这里面还有打开摄像头的函数openCamerapublic static void openCamera(Activity activity, boolean isPIP) throws CameraHardwareException, CameraDisabledException { Log.i(TAG,"openCamera begin isPIP = " + isPIP); // Check if device policy has disabled the camera. DevicePolicyManager dpm = (DevicePolicyManager) activity.getSystemService( Context.DEVICE_POLICY_SERVICE); if (dpm.getCameraDisabled(null)) { throw new CameraDisabledException(); } if (isPIP) { retryOpen(activity, OPEN_RETRY_COUNT, CameraHolder.instance().getBackCameraId()); retryOpen(activity, OPEN_RETRY_COUNT, CameraHolder.instance().getFrontCameraId()); } else { int currentCameraId = ((com.android.camera.Camera)activity).getCameraId(); retryOpen(activity, OPEN_RETRY_COUNT, currentCameraId); } Log.i(TAG,"openCamera end"); } //这里面又会调用一个retryOpen函数 private static CameraManager.CameraProxy retryOpen(Activity activity, int count, int cameraId) //这个函数最终会调用open函数来打开摄像头 try { if (activity instanceof ActivityBase) { CameraProxy cameraProxy = CameraHolder.instance().open(cameraId); return cameraProxy; } else { return CameraHolder.instance().open(cameraId); } ........ }２. 这里面的CameraHolder.instance().open调用了下面的open函数
./packages/apps/Camera/src/com/android/camera/CameraHolder.java
public CameraProxy open(int cameraId) throws CameraHardwareException { Log.i(TAG, "CameraHolder open cameraId = " + cameraId); assertError(cameraId != UNKONW_ID); if (mMockCameraInfo == null) { //这里又有一个open函数 return getCameraProxyWrapper(cameraId).open(); } else { if (mMockCamera == null) { throw new RuntimeException(); } getCameraProxyWrapper(cameraId).insertMockCameraProxy(mMockCamera[cameraId]); return mMockCamera[cameraId]; } } public synchronized CameraProxy open() throws CameraHardwareException { Log.i(TAG, "CameraProxyWrapper open mCameraOpened = " + mCameraOpened + " mCameraId = " + mCameraId); assertError(!mCameraOpened); if (mCameraProxy == null) { try { Log.i(TAG, "open camera " + mCameraId); mCameraProxy = mCameraManager.cameraOpen(mCameraId); //现在又跑到一个mCameraManager.cameraOpen里面来了//看一下下面这个函数，这个函数就是app里面最终调用到framework里面的接口// Open camera synchronously. This method is invoked in the context of a // background thread. CameraProxy cameraOpen(int cameraId) { // Cannot open camera in mCameraHandler, otherwise all camera events // will be routed to mCameraHandler looper, which in turn will call // event handler like Camera.onFaceDetection, which in turn will modify // UI and cause exception like this: // CalledFromWrongThreadException: Only the original thread that created // a view hierarchy can touch its views. MMProfileManager.startProfileCameraOpen(); mCamera = FrameworksClassFactory.openCamera(cameraId); MMProfileManager.stopProfileCameraOpen(); if (mCamera != null) { mParametersIsDirty = true; if (mParamsToSet == null) { mParamsToSet = mCamera.getParameters(); } mCameraProxy = new CameraProxy(); return mCameraProxy; } else { return null; } //./packages/apps/Camera/src/com/mediatek/camera/FrameworksClassFactory.java //代码的路径 camera.open这里就是跑到framework里面去了 public static ICamera openCamera(int cameraId) { if (MOCK_CAMERA) { return MockCamera.open(cameraId); } else { Camera camera = Camera.open(cameraId); if (null == camera) { Log.e(TAG, "openCamera:got null hardware camera!"); return null; } // wrap it with ICamera return new AndroidCamera(camera); } }２、Framework open到jni调用流程
- 还是open这个接口
代码路径：./frameworks/base/core/java/android/hardware/Camera.java
public static Camera open(int cameraId) { if (!isPermissionGranted()) { return null; } return new Camera(cameraId); }//这里的return new Camera就是在下面进行了初始化//填充一些参数 Camera(int cameraId) { mShutterCallback = null; mRawImageCallback = null; mJpegCallback = null; mPreviewCallback = null; mPreviewRawDumpCallback = null; mPostviewCallback = null; mUsingPreviewAllocation = false; mZoomListener = null; Looper looper; if ((looper = Looper.myLooper()) != null) { mEventHandler = new EventHandler(this, looper); } else if ((looper = Looper.getMainLooper()) != null) { mEventHandler = new EventHandler(this, looper); } else { mEventHandler = null; } String packageName = ActivityThread.currentPackageName(); native_setup(new WeakReference(this), cameraId, packageName); } //这个native_setup就是打开摄像头的关键了 - jni的调用接口
看到这个native 函数说明这个函数是在jni接口，用的是c++代码实现的，so，我们继续找
private native final void native_setup(Object camera_this, int cameraId,
终于我们在./frameworks/base/core/jni/android_hardware_Camera.cpp
这里面找到了这个函数，然后我们看一下这个函数
static JNINativeMethod camMethods[] = { { "getNumberOfCameras", "()I", (void *)android_hardware_Camera_getNumberOfCameras }, { "_getCameraInfo", "(ILandroid/hardware/Camera$CameraInfo;)V", (void*)android_hardware_Camera_getCameraInfo }, { "native_setup", "(Ljava/lang/Object;ILjava/lang/String;)V", (void*)android_hardware_Camera_native_setup }, //从这里可以看出来，实现这个函数的真正函数是android_hardware_Camera_native_setup //所以我们继续找一下这个函数在哪里 { "native_release", "()V",３. 下面就是打开摄像头的jni代码，app调用open的时候就会调用到这个位置
// connect to camera servicestatic void android_hardware_Camera_native_setup(JNIEnv *env, jobject thiz, jobject weak_this, jint cameraId, jstring clientPackageName){ // Convert jstring to String16 const char16_t *rawClientName = env->GetStringChars(clientPackageName, NULL); jsize rawClientNameLen = env->GetStringLength(clientPackageName); String16 clientName(rawClientName, rawClientNameLen); env->ReleaseStringChars(clientPackageName, rawClientName); sp<Camera> camera = Camera::connect(cameraId, clientName, Camera::USE_CALLING_UID);//不相关的代码就不加进来了//sp camera = Camera::connect(cameraId, clientName, //这句代码应该是从camera jni连接到camera client的关键 上面有个clientName也说明了这点 .......}３、Android camera Client和camera service调用流程
我只知道spCamera>是一个强指针引用，具体是多厉害百度一下更好
从client的代码里面
frameworks/av/camera/Camera.cpp
sp<Camera> Camera::connect(int cameraId, const String16& clientPackageName, int clientUid){ return CameraBaseT::connect(cameraId, clientPackageName, clientUid); //CameraBaseT::connect这个又是从哪里来的，而且都是c++这可是难倒了我 //不太好办}//在./frameworks/av/include/camera/CameraBase.h:113: //typedef CameraBase CameraBaseT; //里面有一个typedef 好了，那我们下一句就应该去找CameraBase这个东西 //找到在这个位置//./frameworks/av/camera/CameraBase.cpp:94:sp CameraBase::connect(int cameraId, sp<TCam> CameraBase<TCam, TCamTraits>::connect(int cameraId, const String16& clientPackageName, int clientUid){ ALOGV("%s: connect", __FUNCTION__); sp<TCam> c = new TCam(cameraId); sp<TCamCallbacks> cl = c; status_t status = NO_ERROR; //下一步就应该到getCameraService这里来了 //这时候我们就要到cameraservice.java里面去看代码了 const sp<ICameraService>& cs = getCameraService(); if (cs != 0) { TCamConnectService fnConnectService = TCamTraits::fnConnectService; status = (cs.get()->*fnConnectService)(cl, cameraId, clientPackageName, clientUid, /*out*/ c->mCamera); } if (status == OK && c->mCamera != 0) { c->mCamera->asBinder()->linkToDeath(c); c->mStatus = NO_ERROR; } else { ALOGW("An error occurred while connecting to camera: %d", cameraId); c.clear(); } return c;}为了查看它的调用流程，我加了一点日志在connect函数里面，加的日志代码如下
template sp CameraBase::connect(int cameraId, const String16& clientPackageName, int clientUid){ ALOGD("%s: weiqifa connect 23", __FUNCTION__); sp c = new TCam(cameraId); sp cl = c; status_t status = NO_ERROR; const sp& cs = getCameraService(); if (cs != 0) { TCamConnectService fnConnectService = TCamTraits::fnConnectService; status = (cs.get()->*fnConnectService)(cl, cameraId, clientPackageName, clientUid, /*out*/ c->mCamera); ALOGD("%s: weiqifa connect 234", __FUNCTION__); //ALOGD("cs.get()->*fnConnectService %s: weiqifawe", *(cs.get()->*fnConnectService)); } if (status == OK && c->mCamera != 0) { c->mCamera->asBinder()->linkToDeath(c); c->mStatus = NO_ERROR; } else { ALOGW("An error occurred while connecting to camera: %d", cameraId); c.clear(); } return c;} 
我们可以看到CameraBase: connect: weiqifa connect 234这句话已经打印出来了
然后我们也可以看到CameraService::connect X 打印出来了
然后我们也可以看到CameraClient: CameraClient::initialize X这个也打印出来了
上面的三个日志还是非常重要的
看一下cameraservice.cpp的connect函数，service是服务端，client是客户端，那么客户端的实现在服务端应该有一个对应的函数
status_t CameraService::connect( const sp& cameraClient, int cameraId, const String16& clientPackageName, int clientUid, ..... switch(deviceVersion) { case CAMERA_DEVICE_API_VERSION_1_0: client = new CameraClient(this, cameraClient, //new CameraClient 这个new了一个这个东西，那么CameraClient里面的东西就会被调用了 clientPackageName, cameraId, facing, callingPid, clientUid, getpid()); ./frameworks/av/services/camera/libcameraservice/api1/CameraClient.cpp:73:status_t CameraClient::initialize(camera_module_t *module) { int callingPid = getCallingPid(); status_t res; // //看到这里的时候我突然看到了open的函数 //但是有个问题很奇怪这个函数是谁调用了呢？谁让他运行的？？？？？？ LOG1("CameraClient::initialize E (pid %d, id %d)", callingPid, mCameraId); res = mHardware->initialize(&module->common); //这句还是比较关键的mHardware->initialize就是要获取硬件设备的一些东东啊 //...... LOG1("CameraClient::initialize X (pid %d, id %d)", callingPid, mCameraId); return OK;./frameworks/av/services/camera/libcameraservice/device1/CameraHardwareInterface.h
status_t initialize(hw_module_t *module) { ALOGI("Opening camera %s", mName.string()); //通过这几句话去打开设备 int rc = module->methods->open(module, mName.string(), (hw_device_t **)&mDevice); if (rc != OK) { ALOGE("Could not open camera %s: %d", mName.string(), rc); return rc; } initHalPreviewWindow(); return rc; } //日志里面也有这样的打印 01-01 22:23:00.999868 191 748 I CameraClient: Opening camera 0 我们下一步就是要去找到hw_module_t这个结构体，找到了这个结构体就可以往下走
libcameraservice.so里面调用
void CameraService::onFirstRef(){ LOG1("CameraService::onFirstRef weiqifa"); BnCameraService::onFirstRef(); if (hw_get_module(CAMERA_HARDWARE_MODULE_ID, (const hw_module_t **)&mModule) < 0) { ALOGE("Could not load camera HAL module"); mNumberOfCameras = 0; } else { ALOGI("Loaded \"%s\" camera module", mModule->common.name); mNumberOfCameras = mModule->get_number_of_cameras(); if (mNumberOfCameras > MAX_CAMERAS) { ALOGE("Number of cameras(%d) > MAX_CAMERAS(%d).", mNumberOfCameras, MAX_CAMERAS); mNumberOfCameras = MAX_CAMERAS; } //for (int i = 0; i < mNumberOfCameras; i++) { for (int i = 0; i < MAX_CAMERAS; i++) { // workaround for MATV LOG1("setCameraFree(%d)", i); setCameraFree(i); } if (mModule->common.module_api_version >= CAMERA_MODULE_API_VERSION_2_1) { mModule->set_callbacks(this); } CameraDeviceFactory::registerService(this); }}hw_get_module(CAMERA_HARDWARE_MODULE_ID这个是加载硬件hardware层对应的东东，具体可以查看链接hw_get_module获取硬件模块
看一下CAMERA_HARDWARE_MODULE_ID
hardware/libhardware/include/hardware/camera_common.h:35:#define CAMERA_HARDWARE_MODULE_ID "camera"看一下我们打印出来的日志
weiqifa@weiqifa-Inspiron-3847:~/weiqifa/log$ grep -wrn "CameraService::onFirstRef" ././mobilelog/APLog_2010_0105_214945/main_log.boot:922:01-05 22:49:08.208839 194 194 D CameraService: CameraService::onFirstRef weiqifaweiqifa@weiqifa-Inspiron-3847:~/weiqifa/log$ ４、Android camera Hardware调用
hardware肯定是属于平台的特性，所以我们这里就要找到平台特性的东西了。
从libcameraservice下来
if (hw_get_module(CAMERA_HARDWARE_MODULE_ID, (const hw_module_t **)&mModule) < 0) { ALOGE("Could not load camera HAL module"); mNumberOfCameras = 0; }hw_get_module这个东西就是获取hardware下面的内容的东西。具体的可以看一下链接
hw_get_module
然后我们就找到了这个地方
./mediatek/hardware/mtkcam/module/module.h
staticcamera_moduleget_camera_module(){ camera_module module = { common: { tag: HARDWARE_MODULE_TAG, module_api_version: CAMERA_MODULE_API_VERSION_2_1, hal_api_version: HARDWARE_HAL_API_VERSION, id: CAMERA_HARDWARE_MODULE_ID, name: "MediaTek Camera Module", author: "MediaTek", methods: get_module_methods(), dso: NULL, reserved: {0}, }, get_number_of_cameras: get_number_of_cameras, get_camera_info: get_camera_info, set_callbacks: set_callbacks, }; return module;}里面的methods: get_module_methods（）这个就是我们hardware的open函数
open_device(hw_module_t const* module, const char* name, hw_device_t** device){ return NSCam::getCamDeviceManager()->open(module, name, device);}statichw_module_methods_t*get_module_methods(){ static hw_module_methods_t _methods = { open: open_device }; return &_methods;}open_device就会找到NScam：：getCamDeviceManager()->open
NSCam这个是一个命名空间，我看了网上的解释，更像是类引用，后面我再跟进去找到open的地方
./mediatek/hardware/mtkcam/devicemgr/CamDeviceManagerBase.cpp
status_tCamDeviceManagerBase::open( hw_module_t const* module, char const* name, hw_device_t** device){ RWLock::AutoWLock _l(mRWLock); // return openDeviceLocked(module, name, device);}这里调用到了openDeviceLocked 我们找到这个地方
./mediatek/hardware/mtkcam/devicemgr/CamDeviceManagerBase.openDevice.cpp
/****************************************************************************** * ******************************************************************************/status_tCamDeviceManagerBase::openDeviceLocked( hw_module_t const* module, char const* name, hw_device_t** device){ status_t status = OK; sp pDevice = NULL; int32_t const i4OpenId = (name != NULL) ? ::atoi(name) : -1; // String8 const s8ClientAppMode = queryClientAppMode(); uint32_t const version = determineOpenDeviceVersionLocked(s8ClientAppMode, i4OpenId); // MY_LOGD("+ mOpenMap.size:%d mEnumMap.size:%d", mOpenMap.size(), mEnumMap.size()); // // [1] check to see whether it's ready to open. if ( OK != (status = validateOpenLocked(i4OpenId)) ) { return status; } // // [2] get platform IPlatform*const pPlatform = getPlatform(); if ( ! pPlatform ) { MY_LOGE("No Platform"); return NAME_NOT_FOUND; } // // [3] create device based on device version. if ( version == CAMERA_DEVICE_API_VERSION_1_0 ) { pDevice = pPlatform->createCam1Device(s8ClientAppMode.string(), i4OpenId); } else if ( version >= CAMERA_DEVICE_API_VERSION_3_0 ) { MY_LOGE("Unsupported version:0x%x >= CAMERA_DEVICE_API_VERSION_3_0", version); return UNKNOWN_ERROR; } else { MY_LOGE("Unsupported version:0x%x", version); return UNKNOWN_ERROR; } // if ( pDevice == 0 ) { MY_LOGE("device creation failure"); return NO_MEMORY; } // // [4] open device successfully. { *device = const_cast(pDevice->get_hw_device()); // pDevice->set_hw_module(module); pDevice->set_module_callbacks(mpModuleCallbacks); pDevice->setDeviceManager(this); // attachDeviceLocked(pDevice); } // return OK;} 更多相关文章
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