Android50Camera系统源码分析(5)Camera预览3A流程

Android5.0Camera系统源码分析(5)：Camera预览3A流程1.前言本文分析的是AndroidHal层的源码，硬件平台基于mt6735。之前几篇讲的预览流程中3A相关的环节都忽略了，现在重新整理下。3A指的是AutoExposure，AutoFocus，AutoWhiteBalance。这三个一起放上来代码实在太多了，这里将重点记录AF的代码。AF的部分工作是由ISP完成的，而ISP的大部分代码mtk都没有开放给我们，比如ISP是如何计算得到对焦位置信息的，但得到对焦位置之后怎么操作对焦马达的代码我们是看得到的，所以涉及到ISP的一些代码将被略过2.初始化3A3A的初始化在DefaultCam1Device的onInit函数里面开始，之前在camera打开流程里面已经提到过boolDefaultCam1Device::onInit(){......//(1)Open3AmpHal3a=NS3A::IHal3A::createInstance(NS3A::IHal3A::E_Camera_1,getOpenId(),LOG_TAG);......}构造一个Hal3A对象，看下Hal3A::createInstance的实现Hal3A*Hal3A::createInstance(MINT32i4SensorDevId,MINT32i4SensorOpenIndex){switch(i4SensorDevId){caseSENSOR_DEV_MAIN:Hal3ADevSENSOR_DEV_MAIN::getInstance()-init(i4SensorDevId,i4SensorOpenIndex);returnHal3ADevSENSOR_DEV_MAIN::getInstance();break;caseSENSOR_DEV_SUB:Hal3ADevSENSOR_DEV_SUB::getInstance()-init(i4SensorDevId,i4SensorOpenIndex);returnHal3ADevSENSOR_DEV_SUB::getInstance();break;......}}其实这里的Hal3A并没有直接继承IHal3A，也就是说从IHal3A::createInstance到Hal3A::createInstance的调用过程经历了一番波折，但暂时不用关心它。从Hal3A::createInstance可以看到除了实例化以外还会调用init函数。构造函数没什么好看的-略过，直接看init函数MRESULTHal3A::init(MINT32i4SensorDevId,MINT32i4SensorOpenIndex){......//(1)mpStateMgr=newStateMgr(i4SensorDevId);//(2)bRet=postCommand(ECmd_Init);//(3)createThread();//(4)bRet=IspTuningMgr::getInstance().init(m_i4SensorDev,m_i4SensorOpenIdx);//(5)ret=EnableAFThread(1);......returnS_3A_OK;}步骤(1)newStateMgr，构造函数如下StateMgr::StateMgr(MINT32sensorDevId):......{#defineSTATE_INITIALIZE(_state_)\mpIState[eState_##_state_]=newState##_state_(sensorDevId,this);STATE_INITIALIZE(Init);STATE_INITIALIZE(Uninit);STATE_INITIALIZE(CameraPreview);STATE_INITIALIZE(CamcorderPreview);STATE_INITIALIZE(Recording);STATE_INITIALIZE(Precapture);STATE_INITIALIZE(Capture);STATE_INITIALIZE(AF);mpCurrentState=mpIState[eState_Uninit];}初始化3A的状态管理，将各个子状态都保存在mpIState数组里面，并将当前状态设置为Uninit状态步骤(2)postCommandMBOOLHal3A::postCommand(ECmd_TconsteCmd,MINTPTRconsti4Arg){......ERROR_CHECK(mpStateMgr-sendCmd(eCmd))......}MRESULTStateMgr::sendCmd(ECmd_TeCmd){Mutex::Autolocklock(m_Lock);EIntent_TeNewIntent=static_castEIntent_T(eCmd);#defineSEND_INTENT(_intent_)\case_intent_:returnmpCurrentState-sendIntent(intent2type_intent_());\switch(eNewIntent){SEND_INTENT(eIntent_CameraPreviewStart)SEND_INTENT(eIntent_CameraPreviewEnd)SEND_INTENT(eIntent_CaptureStart)SEND_INTENT(eIntent_CaptureEnd)SEND_INTENT(eIntent_RecordingStart)SEND_INTENT(eIntent_RecordingEnd)SEND_INTENT(eIntent_AFUpdate)SEND_INTENT(eIntent_AFStart)SEND_INTENT(eIntent_AFEnd)SEND_INTENT(eIntent_Init)SEND_INTENT(eIntent_Uninit)}return-1;}从步骤(1)可以看出这里的mpCurrentState指向的是StateUninit对象，所以接着看StateUninit的sendIntent函数MRESULTStateUninit::sendIntent(intent2typeeIntent_Init){MY_LOG([StateUninit::sendIntent]eIntent_Init);//AAODMAbufferinitMINT32i4SensorIdx=m_pHal3A-getSensorOpenIdx();if(ENABLE_3A_GENERAL&m_pHal3A-m_3ACtrlEnable){if(ENABLE_AAOBUF&m_pHal3A-m_3ACtrlEnable){//AAODMAbufferinitif(!IAAOBufMgr::getInstance().init(m_SensorDevId,i4SensorIdx)){MY_ERR(IAAOBufMgr::getInstance().init()fail);returnE_3A_ERR;}if(!IAEBufMgr::getInstance().init(m_SensorDevId,i4SensorIdx)){MY_ERR(IAEBufMgr::getInstance().init()fail);returnE_3A_ERR;}}if(ENABLE_AFOBUF&m_pHal3A-m_3ACtrlEnable){//AFODMAbufferinitif(!IAFOBufMgr::getInstance().init(m_SensorDevId,i4SensorIdx)){MY_ERR(IAFOBufMgr::getInstance().init()fail);returnE_3A_ERR;}}}//Statetransition:eState_Uninit--eState_Initm_pStateMgr-transitState(eState_Uninit,eState_Init);returnS_3A_OK;}做了一堆乱七八糟的初始化之后将3A状态从Uninit状态切换到Init状态步骤(3)createThread和步骤(5)EnableAFThreadMVOIDHal3A::createThread(){......pthread_create(&mThread,NULL,onThreadLoop,this);pthread_create(&mPDThread,NULL,PDThreadLoop,this);pthread_create(&mPDVCThread,NULL,PDVCThreadLoop,this);......}MRESULTHal3A::EnableAFThread(MINT32a_bEnable){if(a_bEnable){if(mbAFThreadLoop==0){......pthread_create(&mAFThread,&attr,AFThreadFunc,this);}}else{......}returnret;}一共创建了4个线程，暂时只关心onThreadLoop和AFThreadFunc。onThreadLoop是3A主线程，负责接收处理命令；AFThreadFunc负责实时更新AF参数3.处理PASS1_START_ISP事件前面的3A初始化做的事情并不多，更多的准备工作是在接收到PASS1_START_ISP事件之后做的，PASS1_START_ISP事件是在之前的Camera预览流程控制流中提到的Pass1Node的startHw函数里面发送MBOOLPass1NodeImpl::startHw(listHwPortConfig_t&plPortCfg){......handleNotify(PASS1_START_ISP,newMagicNum,0);......}3.1DefaultCtrlNode接收处理PASS1_START_ISP事件Pass1Node发出的event将在DefaultCtrlNode的onNotify函数中接收处理MBOOLDefaultCtrlNodeImpl::onNotify(MUINT32constmsg,MUINT32constext1,MUINT32constext2){switch(msg){casePASS1_START_ISP:{if(mpHal3a){cmd=ECmd_CameraPreviewStart;......mpHal3a-sendCommand(cmd);}casePASS1_STOP_ISP:{......}casePASS1_EOF:{......}default:{ret=MTRUE;}}returnret;}Hal3a的sendCommand函数会把命令加入到命令队列，然后由主线程onThreadLoop获取MVOID*Hal3A::onThreadLoop(MVOID*arg){while(_this-getCommand(rCmd,bGetCmd,MFALSE)){switch(rCmd.eCmd){caseECmd_PrecaptureStart:{......}caseECmd_Update:{......}default:if(!_this-postCommand(rCmd.eCmd,reinterpret_castMINTPTR(&rCmd.rParamIspProfile))){MY_ERR(Cmd(%d)failed(0x%x),rCmd.eCmd,_this-getErrorCode());AEE_ASSERT_3A_HAL(onThreadLooppos