安卓camera拍照时序

转自：http://blog.csdn.net/tankai19880619/article/details/17147125

一、看看调用时序图

1.拍照命令时序图

2.拍照数据回调时序图

二、看看源码分析

hardware/amlogic/camera/CameraHal.cpp

 status_t CameraHal::takePicture( ){
   ret = mCameraAdapter->sendCommand(CameraAdapter::CAMERA_START_IMAGE_CAPTURE,  (int) &mStartCapture);
 }

调用父类方法：

hardware/amlogic/camera/BaseCameraAdapter.cpp

 status_t BaseCameraAdapter::sendCommand(CameraCommands operation, int value1, int value2, int value3){
   switch ( operation ) {
     case CameraAdapter::CAMERA_START_IMAGE_CAPTURE:
       ret = takePicture();
   }
 }

调用子类方法：

hardware/amlogic/camera/V4LCameraAdapter/V4LCameraAdapter.cpp

 status_t V4LCameraAdapter::takePicture(){
   if (createThread(beginPictureThread, this) == false)
     return -1;
 }
 /*static*/ int V4LCameraAdapter::beginPictureThread(void *cookie){
   V4LCameraAdapter *c = (V4LCameraAdapter *)cookie;
   return c->pictureThread();
 }
 int V4LCameraAdapter::pictureThread(){
   ret = sendFrameToSubscribers(&frame);
 }

调用父类方法：

hardware/amlogic/camera/BaseCameraAdapter.cpp

 status_t BaseCameraAdapter::sendFrameToSubscribers(CameraFrame *frame){
   ret = __sendFrameToSubscribers(frame, &mImageSubscribers, CameraFrame::IMAGE_FRAME);
 /*
 //如上callback的设置
 hardware/amlogic/camera/CameraHal.cpp
 status_t CameraHal::initialize(CameraProperties::Properties* properties){
   mAppCallbackNotifier->setEventProvider(eventMask, mCameraAdapter);
   mAppCallbackNotifier->setFrameProvider(mCameraAdapter);
 }

 hardware/amlogic/camera/AppCallbackNotifier.cpp
 void AppCallbackNotifier::setFrameProvider(FrameNotifier *frameNotifier){
   mFrameProvider = new FrameProvider(frameNotifier, this, frameCallbackRelay);
   mFrameProvider->enableFrameNotification(CameraFrame::IMAGE_FRAME);
   mFrameProvider->enableFrameNotification(CameraFrame::RAW_FRAME);
 }

 hardware/amlogic/camera/inc/CamerHal.h
 class FrameProvider{
   public:
     FrameProvider(FrameNotifier *fn, void* cookie, frame_callback frameCallback)
                   :mFrameNotifier(fn), mCookie(cookie),mFrameCallback(frameCallback) { }
 }
 hardware/amlogic/camera/CameraHalUtilClasses.cpp
 int FrameProvider::enableFrameNotification(int32_t frameTypes){
   mFrameNotifier->enableMsgType(frameTypes<<MessageNotifier::FRAME_BIT_FIELD_POSITION
                                 , mFrameCallback
                                 , NULL
                                 , mCookie);
 }
 hardware/amlogic/camera/BaseCameraAdapter.cpp
 void BaseCameraAdapter::enableMsgType(int32_t msgs, frame_callback callback, event_callback eventCb, void* cookie){
   if ( CameraFrame::PREVIEW_FRAME_SYNC == msgs ){
     mFrameSubscribers.add((int) cookie, callback);
   }
   else if ( CameraFrame::IMAGE_FRAME == msgs){
     mImageSubscribers.add((int) cookie, callback);
   }
   else if ( CameraFrame::RAW_FRAME == msgs){
     mRawSubscribers.add((int) cookie, callback);
   }
 }
 //以下callback就是frameCallbackRelay
 //callbak-》subscribers-》mImageSubscribers-》mImageSubscribers.add((int) cookie, callback)-》mFrameCallback-》frameCallbackRelay
 */
 }
 status_t BaseCameraAdapter::__sendFrameToSubscribers(CameraFrame* frame,
      KeyedVector<int, frame_callback> *subscribers,
      CameraFrame::FrameType frameType){
   callback = (frame_callback) subscribers->valueAt(k);
   callback(frame);
 }

该回调函数即是：

hardware/amlogic/camera/AppCallbackNotifier.cpp

 void AppCallbackNotifier::frameCallbackRelay(CameraFrame* caFrame){
   appcbn->frameCallback(caFrame);
 }
 void AppCallbackNotifier::frameCallback(CameraFrame* caFrame){
   msg.command = AppCallbackNotifier::NOTIFIER_CMD_PROCESS_FRAME;
   msg.arg1 = frame;
   mFrameQ.put(&msg);
 }
 void AppCallbackNotifier::notifyFrame(){
   mFrameQ.get(&msg);
   sp<Encoder_libjpeg> encoder = new Encoder_libjpeg(main_jpeg, tn_jpeg,
     AppCallbackNotifierEncoderCallback,
     (CameraFrame::FrameType)frame->mFrameType,
     this,raw_picture,exif_data);
 }

补充——拍照是声音的回调如下：

frameworks/av/services/camera/libcameraservice/CameraClient.cpp

 void CameraClient::handleShutter(void) {
   mCameraService->playSound(CameraService::SOUND_SHUTTER);
 }

frameworks/av/services/camera/libcameraservice/CameraService.cpp

 //mSoundPlayer[SOUND_SHUTTER] = newMediaPlayer("/system/media/audio/ui/camera_click.ogg");
 void CameraService::playSound(sound_kind kind) {

 }

源码中位置：

frameworks/base/data/sounds/OriginalAudio.mk

 $(LOCAL_PATH)/effects/camera_click.ogg:system/media/audio/ui/camera_click.ogg

frameworks/base/data/sounds/effects/camera_click.ogg

三、项目问题

拍照后，应用程序不调用startPreview导致预览界面不再刷新：

1.看看预览部分CameraHAL的处理

hardware/amlogic/camera/V4LCameraAdapter/V4LCameraAdapter.cpp

 int V4LCameraAdapter::previewThread(){
   frame.mFrameMask |= CameraFrame::PREVIEW_FRAME_SYNC;
   ret = sendFrameToSubscribers(&frame);
 }

hardware/amlogic/camera/BaseCameraAdapter.cpp

 status_t BaseCameraAdapter::sendFrameToSubscribers(CameraFrame *frame){
   ret = __sendFrameToSubscribers(frame, &mFrameSubscribers, CameraFrame::PREVIEW_FRAME_SYNC);
 }
 status_t BaseCameraAdapter::__sendFrameToSubscribers(CameraFrame* frame,
                                                       KeyedVector<int, frame_callback> *subscribers,
                                                       CameraFrame::FrameType frameType){
   while(k<subscribers->size()){
     callback = (frame_callback) subscribers->valueAt(k);
     for(uint32_t i = 0; i<subscribers_ref.size();i++){
       if((frame->mCookie == ( void * ) subscribers_ref.keyAt(i))&&(subscribers_ref.valueAt(i) == 0)){
       subscribers_ref.replaceValueFor((uint32_t)frame->mCookie,1);
       //CAMHAL_LOGDB("Frame callbback is available, cookie:0x%x, callback:0x%x",(uint32_t)frame->mCookie,(uint32_t)callback);
       callback(frame);
       k = 0;
       is_find = true;
       break;
     }
   }
 }
 /*
 //如上callback的设置
 hardware/amlogic/camera/CameraHal.cpp
 //设置APP回调函数
 status_t CameraHal::initialize(CameraProperties::Properties* properties){
   mAppCallbackNotifier->setEventProvider(eventMask, mCameraAdapter);
   mAppCallbackNotifier->setFrameProvider(mCameraAdapter);
 }
 //设置刷屏回调函数
 status_t CameraHal::setPreviewWindow(struct preview_stream_ops *window){
   mDisplayAdapter->setFrameProvider(mCameraAdapter);
   mDisplayAdapter->setErrorHandler(mAppCallbackNotifier.get());
   ret  = mDisplayAdapter->setPreviewWindow(window);
 }
 status_t CameraHal::startPreview(){
   ret = mDisplayAdapter->enableDisplay(width, height, NULL, isS3d ? &s3dParams : NULL);
 }

 //设置APP回调函数
 hardware/amlogic/camera/AppCallbackNotifier.cpp
 void AppCallbackNotifier::setFrameProvider(FrameNotifier *frameNotifier){
   mFrameProvider = new FrameProvider(frameNotifier, this, frameCallbackRelay);
   mFrameProvider->enableFrameNotification(CameraFrame::IMAGE_FRAME);
   mFrameProvider->enableFrameNotification(CameraFrame::RAW_FRAME);
 }

 //设置刷屏回调函数
 hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp
 int ANativeWindowDisplayAdapter::setFrameProvider(FrameNotifier *frameProvider){
   mFrameProvider = new FrameProvider(frameProvider, this, frameCallbackRelay);
 }
 int ANativeWindowDisplayAdapter::enableDisplay(int width, int height, struct timeval *refTime, S3DParameters *s3dParams){
   mFrameProvider->enableFrameNotification(CameraFrame::PREVIEW_FRAME_SYNC);
 }

 //最终设置地方
 hardware/amlogic/camera/inc/CamerHal.h
 class FrameProvider{
   public:
     FrameProvider(FrameNotifier *fn, void* cookie, frame_callback frameCallback)
                   :mFrameNotifier(fn), mCookie(cookie),mFrameCallback(frameCallback) { }
 }
 hardware/amlogic/camera/CameraHalUtilClasses.cpp
 int FrameProvider::enableFrameNotification(int32_t frameTypes){
   mFrameNotifier->enableMsgType(frameTypes<<MessageNotifier::FRAME_BIT_FIELD_POSITION
                                 , mFrameCallback
                                 , NULL
                                 , mCookie);
 }
 hardware/amlogic/camera/BaseCameraAdapter.cpp
 void BaseCameraAdapter::enableMsgType(int32_t msgs, frame_callback callback, event_callback eventCb, void* cookie){
   if ( CameraFrame::PREVIEW_FRAME_SYNC == msgs ){
     mFrameSubscribers.add((int) cookie, callback);
   }
   else if ( CameraFrame::IMAGE_FRAME == msgs){
     mImageSubscribers.add((int) cookie, callback);
   }
   else if ( CameraFrame::RAW_FRAME == msgs){
     mRawSubscribers.add((int) cookie, callback);
 }
 }
 */

如上callback即是ANativeWindowDisplayAdapter.cpp/AppCallbackNotifier.cpp中的frameCallbackRelay，我们分析预览画面只需要关心ANativeWindowDisplayAdapter.cpp（AppCallbackNotifier.cpp是例如拍照和录像，需要将数据送给APP）：

hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp

 void ANativeWindowDisplayAdapter::frameCallbackRelay(CameraFrame* caFrame){
   da->frameCallback(caFrame);
 }
 void ANativeWindowDisplayAdapter::frameCallback(CameraFrame* caFrame){
   PostFrame(df);
 }
 status_t ANativeWindowDisplayAdapter::PostFrame(ANativeWindowDisplayAdapter::DisplayFrame &dispFrame){
   LOGD("TK----->>>>mPaused is %d\n",mPaused);//add by tankai
   if ( mDisplayState == ANativeWindowDisplayAdapter::DISPLAY_STARTED &&
                 (!mPaused ||  CameraFrame::CameraFrame::SNAPSHOT_FRAME == dispFrame.mType) &&
                 !mSuspend){
     ret = mANativeWindow->enqueue_buffer(mANativeWindow, mBufferHandleMap[i]);
     mFramesWithCameraAdapterMap.removeItem((int) dispFrame.mBuffer);
   }
   else{
     ret = mANativeWindow->cancel_buffer(mANativeWindow, mBufferHandleMap[i]);
     mFramesWithCameraAdapterMap.removeItem((int) dispFrame.mBuffer);
   }
 }

2.问题分析

从如上可以看出：mPaused为true表示暂停刷屏，mPaused为false表示开始刷屏；我们的问题就出在这里。

hardware/camera/CameraHal.cpp

 status_t CameraHal::startPreview(){
   if( (mDisplayAdapter.get() != NULL) && ( !mPreviewEnabled ) && ( mDisplayPaused ) ){
     CAMHAL_LOGDA("Preview is in paused state");
     mDisplayPaused = false;
     mPreviewEnabled = true;
     if ( NO_ERROR == ret ){
       ret = mDisplayAdapter->pauseDisplay(mDisplayPaused); //重新开始预览
 /*
 hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp
 status_t ANativeWindowDisplayAdapter::pauseDisplay(bool pause){
   mPaused = pause;
 }
 */
       if ( NO_ERROR != ret ){
         CAMHAL_LOGEB("Display adapter resume failed %x", ret);
       }
     }
     //restart preview callbacks
     if(mMsgEnabled & CAMERA_MSG_PREVIEW_FRAME){
       mAppCallbackNotifier->enableMsgType (CAMERA_MSG_PREVIEW_FRAME);
     }
     return ret;
   }
 }
 //拍照时将mPaused置为false，暂停刷屏：
 status_t CameraHal::takePicture( ){
   if (NO_ERROR == ret &&
     NULL != mDisplayAdapter.get() && burst < 1) {
     if (mCameraAdapter->getState() != CameraAdapter::VIDEO_STATE) {
       mDisplayPaused = true;
       mPreviewEnabled = false;
       ret = mDisplayAdapter->pauseDisplay(mDisplayPaused); //暂停预览
 /*
 hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp
 status_t ANativeWindowDisplayAdapter::pauseDisplay(bool pause){
   mPaused = pause;
 }
 */
       // since preview is paused we should stop sending preview frames too
       if(mMsgEnabled & CAMERA_MSG_PREVIEW_FRAME) {
         mAppCallbackNotifier->disableMsgType (mMsgEnabled & CAMERA_MSG_POSTVIEW_FRAME);
         CAMHAL_LOGDA("disable MSG_PREVIEW_FRAME");
       }
     }

 #if PPM_INSTRUMENTATION || PPM_INSTRUMENTATION_ABS
      mDisplayAdapter->setSnapshotTimeRef(&mStartCapture);
 #endif
   }

 }

3.问题解决

应用层在take_picture之后主动调用startpreview将mPaused改为false；

如果不需要应用主动调用，则需要在HAL将startpreview设为false。

4.如何在应用层取消掉拍照的回调

 camera.takePicture(shutterCallback, rawCallback, jpegCallback);
 改为
 camera.takePicture(null, null, jpegCallback);

原理如下：

frameworks/base/core/java/android/hardware/Camera.java

 public final void takePicture(ShutterCallback shutter, PictureCallback raw,
             PictureCallback postview, PictureCallback jpeg) {
         mShutterCallback = shutter;
         mRawImageCallback = raw;
         mPostviewCallback = postview;
         mJpegCallback = jpeg;

         // If callback is not set, do not send me callbacks.
         int msgType = 0;
         if (mShutterCallback != null) {
             msgType |= CAMERA_MSG_SHUTTER;
         }
         if (mRawImageCallback != null) {
             msgType |= CAMERA_MSG_RAW_IMAGE;
         }
         if (mPostviewCallback != null) {
             msgType |= CAMERA_MSG_POSTVIEW_FRAME;
         }
         if (mJpegCallback != null) {
             msgType |= CAMERA_MSG_COMPRESSED_IMAGE;
         }

         native_takePicture(msgType);
         mFaceDetectionRunning = false;
     }