Android之Camera预览

一、命令流程

1.APP

packages/apps/Camera/src/com/Android/camera/PhotoModule.Java

[java] view plain copy

 

1. private void startPreview() {  
2.   mCameraDevice.setPreviewDisplayAsync(mCameraSurfaceHolder);  
3.   mCameraDevice.startPreviewAsync();  
4. }  

packages/apps/Camera/src/com/android/camera/CameraManager.java

[java] view plain copy

 

1. public void setPreviewDisplayAsync(final SurfaceHolder surfaceHolder) {  
2.   mCameraHandler.obtainMessage(SET_PREVIEW_DISPLAY_ASYNC, surfaceHolder).sendToTarget();  
3. }  
4. public void startPreviewAsync() {  
5.   mCameraHandler.sendEmptyMessage(START_PREVIEW_ASYNC);  
6. }  
7. public void handleMessage(final Message msg) {  
8.   switch (msg.what) {  
9.     case SET_PREVIEW_DISPLAY_ASYNC:  
10.       try {  
11.         mCamera.setPreviewDisplay((SurfaceHolder) msg.obj);  
12.       } catch(IOException e) {  
13.           throw new RuntimeException(e);  
14.       }  
15.       return;  // no need to call mSig.open()  
16.     case START_PREVIEW_ASYNC:  
17.       mCamera.startPreview();  
18.       return;  // no need to call mSig.open()  
19.   }  
20. }  

2.frameworks

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

[java] view plain copy

 

1. public final void setPreviewDisplay(SurfaceHolder holder) throws IOException {  
2.   setPreviewDisplay(holder.getSurface());  
3. }  
4. public native final void startPreview();  

frameworks/base/core/jni/android_hardware_Camera.cpp

[cpp] view plain copy

 

1. static void android_hardware_Camera_setPreviewDisplay(JNIEnv *env, jobject thiz, jobject jSurface){  
2.   sp<Camera> camera = get_native_camera(env, thiz, NULL);  
3.   if (camera->setPreviewDisplay(surface) != NO_ERROR) {  
4.     jniThrowException(env, "java/io/IOException", "setPreviewDisplay failed");  
5.   }  
6. }  
7. static void android_hardware_Camera_startPreview(JNIEnv *env, jobject thiz){  
8.   sp<Camera> camera = get_native_camera(env, thiz, NULL);  
9.   if (camera->startPreview() != NO_ERROR) {  
10.     jniThrowRuntimeException(env, "startPreview failed");  
11.     return;  
12.   }  
13. }  

frameworks/av/camera/Camera.cpp

[cpp] view plain copy

 

1. status_t Camera::setPreviewDisplay(const sp<Surface>& surface){  
2.   sp <ICamera> c = mCamera;  
3.   return c->setPreviewDisplay(surface);  
4. }  
5. status_t Camera::startPreview(){  
6.   sp <ICamera> c = mCamera;  
7.   return c->startPreview();  
8. }  

Binder调用

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

[cpp] view plain copy

 

1. status_t CameraClient::setPreviewDisplay(const sp<Surface>& surface) {  
2.   return setPreviewWindow(binder, window);  
3. }  
4. status_t CameraClient::startPreview() {  
5.   return startCameraMode(CAMERA_PREVIEW_MODE);  
6. }  
7. status_t CameraClient::startCameraMode(camera_mode mode) {  
8.   switch(mode) {  
9.     case CAMERA_PREVIEW_MODE:  
10.       return startPreviewMode();  
11.   }  
12. }  
13. status_t CameraClient::startPreviewMode() {  
14.   mHardware->setPreviewWindow(mPreviewWindow);  
15.   result = mHardware->startPreview();  
16. }  

frameworks/av/services/camera/libcameraservice/CameraHardwareInterface.h

[cpp] view plain copy

 

1. status_t setPreviewWindow(const sp<ANativeWindow>& buf){  
2.   mPreviewWindow = buf;  
3.   /* 
4.   #define anw(n) __to_anw(((struct camera_preview_window *)n)->user) 
5.   static ANativeWindow *__to_anw(void *user){ 
6.     CameraHardwareInterface *__this = 
7.                 reinterpret_cast<CameraHardwareInterface *>(user); 
8.     return __this->mPreviewWindow.get(); 
9.   } 
10.   */  
11.   return mDevice->ops->set_preview_window(mDevice,  
12.                     buf.get() ? &mHalPreviewWindow.nw : 0);  
13.   /* 
14.   void initHalPreviewWindow(){ 
15.     mHalPreviewWindow.nw.cancel_buffer = __cancel_buffer; 
16.     mHalPreviewWindow.nw.lock_buffer = __lock_buffer; 
17.     mHalPreviewWindow.nw.dequeue_buffer = __dequeue_buffer; 
18.     mHalPreviewWindow.nw.enqueue_buffer = __enqueue_buffer; 
19.     mHalPreviewWindow.nw.set_buffer_count = __set_buffer_count; 
20.     mHalPreviewWindow.nw.set_buffers_geometry = __set_buffers_geometry; 
21.     mHalPreviewWindow.nw.set_crop = __set_crop; 
22.     mHalPreviewWindow.nw.set_timestamp = __set_timestamp; 
23.     mHalPreviewWindow.nw.set_usage = __set_usage; 
24.     mHalPreviewWindow.nw.set_swap_interval = __set_swap_interval; 
25.  
26.  
27.     mHalPreviewWindow.nw.get_min_undequeued_buffer_count = 
28.                 __get_min_undequeued_buffer_count; 
29.   } 
30.   */  
31. }  
32. status_t startPreview(){  
33.   return mDevice->ops->start_preview(mDevice);  
34. }  

3.HAL

hardware/amlogic/camera/CameraHal_Module.cpp

[cpp] view plain copy

 

1. int camera_set_preview_window(struct camera_device * device,  
2.         struct preview_stream_ops *window){  
3.   rv = gCameraHals[aml_dev->cameraid]->setPreviewWindow(window);  
4. }  
5. int camera_start_preview(struct camera_device * device){  
6.   rv = gCameraHals[aml_dev->cameraid]->startPreview();  
7. }  

hardware/amlogic/camera/CameraHal.cpp

[cpp] view plain copy

 

1. status_t CameraHal::setPreviewWindow(struct preview_stream_ops *window){  
2.   mDisplayAdapter = new ANativeWindowDisplayAdapter();  
3.   mDisplayAdapter->setFrameProvider(mCameraAdapter); //将frameCallbackRelay设置为BaseCameraAdapter的回调函数  
4.   mDisplayAdapter->setErrorHandler(mAppCallbackNotifier.get()); //设置BaseCameraAdapter错误处理函数  
5.   ret  = mDisplayAdapter->setPreviewWindow(window);//设置post的Surface  
6.   /* 
7.   hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp 
8.   int ANativeWindowDisplayAdapter::setPreviewWindow(preview_stream_ops_t* window){ 
9.     mANativeWindow = window; 
10.   } 
11.   */  
12. }  
13. status_t CameraHal::startPreview(){  
14.   //hardware/amlogic/camera/inc/V4LCameraAdapter/V4LCameraAdapter.h  
15.   //#define DEFAULT_PREVIEW_PIXEL_FORMAT        V4L2_PIX_FMT_NV21  
16.   ret = allocPreviewBufs(mPreviewWidth, mPreviewHeight, mParameters.getPreviewFormat(), required_buffer_count, max_queueble_buffers);  
17.   /* 
18.   status_t CameraHal::allocPreviewBufs(int width, int height, const char* previewFormat, 
19.                                         unsigned int buffercount, unsigned int &max_queueable){ 
20.     mPreviewBufs = (int32_t *) mDisplayAdapter->allocateBuffer(width, height, 
21.                                                                     previewFormat, 
22.                                                                     mPreviewLength, 
23.                                                                     buffercount); 
24.   } 
25.   hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp 
26.   void* ANativeWindowDisplayAdapter::allocateBuffer(int width, int height, const char* format, int &bytes, int numBufs){ 
27.     err = mANativeWindow->set_buffers_geometry( 
28.             mANativeWindow, 
29.             width, 
30.             height, 
31.             mNativeWindowPixelFormat); //NV21 
32.   } 
33.   frameworks/av/services/camera/libcameraservice/CameraHardwareInterface.h 
34.   static int __set_buffers_geometry(struct preview_stream_ops* w, 
35.                        int width, int height, int format){ 
36.     ANativeWindow *a = anw(w); 
37.     //#define anw(n) __to_anw(((struct camera_preview_window *)n)->user) 
38.     //__this->mPreviewWindow.get(); 
39.     return native_window_set_buffers_geometry(a, 
40.                            width, height, format); 
41.   } 
42.   */  
43. }  

二、数据流程

hardware/amlogic/camera/V4LCameraAdapter/V4LCameraAdapter.cpp

[cpp] view plain copy

 

1. int V4LCameraAdapter::previewThread(){  
2.   yuyv422_to_nv21(src,dest,width,height);  
3.   frame.mFrameMask |= CameraFrame::PREVIEW_FRAME_SYNC;  
4.   frame.mPixelFmt = mPixelFormat;  
5.   ret = sendFrameToSubscribers(&frame);  
6. }  

hardware/amlogic/camera/BaseCameraAdapter.cpp

[cpp] view plain copy

 

1. status_t BaseCameraAdapter::sendFrameToSubscribers(CameraFrame *frame){  
2.   ret = __sendFrameToSubscribers(frame, &mFrameSubscribers, CameraFrame::PREVIEW_FRAME_SYNC);  
3. }  
4. status_t BaseCameraAdapter::__sendFrameToSubscribers(CameraFrame* frame,  
5.                                                      KeyedVector<int, frame_callback> *subscribers,  
6.                                                      CameraFrame::FrameType frameType){  
7.   callback = (frame_callback) subscribers->valueAt(k);  
8.   callback(frame);  
9. }  

hardware/amlogic/camera/ANativeWindowDisplayAdapter.cpp

[cpp] view plain copy

 

1. void ANativeWindowDisplayAdapter::frameCallbackRelay(CameraFrame* caFrame){  
2.   ANativeWindowDisplayAdapter *da = (ANativeWindowDisplayAdapter*) caFrame->mCookie;  
3.   da->frameCallback(caFrame);  
4. }  
5. void ANativeWindowDisplayAdapter::frameCallback(CameraFrame* caFrame){  
6.   PostFrame(df);  
7. }  
8. status_t ANativeWindowDisplayAdapter::PostFrame(ANativeWindowDisplayAdapter::DisplayFrame &dispFrame){  
9.   mANativeWindow->set_crop(mANativeWindow, xOff/bytesPerPixel, yOff,  
10.                                      (xOff/bytesPerPixel)+mPreviewWidth, yOff+mPreviewHeight);  
11.   ret = mANativeWindow->enqueue_buffer(mANativeWindow, mBufferHandleMap[i]);  
12. }  

frameworks/av/services/camera/libcameraservice/CameraHardwareInterface.h

[cpp] view plain copy

 

1. static int __set_crop(struct preview_stream_ops *w,  
2.                        int left, int top, int right, int bottom){  
3.   ANativeWindow *a = anw(w);  
4.   return native_window_set_crop(a, &crop);  
5. }  
6. static int __enqueue_buffer(struct preview_stream_ops* w,  
7.                        buffer_handle_t* buffer){  
8.   ANativeWindow *a = anw(w);  
9.   return a->queueBuffer(a,  
10.                    container_of(buffer, ANativeWindowBuffer, handle), -1);  
11. }