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;
}