Android4.4-Camera-app初始化分析.doc

Android4.4 Camera app初始化分析Camera app提供的主要功能：预览，拍照，摄影，全景拍摄而这些功能统一组织在CameraActivity这个组件中，并细分到各个模块逐步实现。其中涉及的类如下图PhotoModule：负责与拍照相关的部分VideoModule：负责与视频录制相关的部分WideAnglePanoramaModule：全景照片的拍摄接下来我们分析PhotoModule启动过程，其他两个模块类似。首先给出时序图，结合时序图，分析每一步的实现Step1：CameraActivity.onCreate()当在launcher界面点击camera图标的时候，该函数首先被调用。public void onCreate(Bundle state) setContentView(R.layout.camera_filmstrip);LayoutInflater inflater = getLayoutInflater(); View rootLayout = inflater.inflate(R.layout.camera, null, false); mCameraModuleRootView = rootLayout.findViewById(R.id.camera_app_root); mPanoStitchingPanel = findViewById(R.id.pano_stitching_progress_panel); mBottomProgress = (ProgressBar) findViewById(R.id.pano_stitching_progress_bar); mCameraPreviewData = new CameraPreviewData(rootLayout, FilmStripView.ImageData.SIZE_FULL, FilmStripView.ImageData.SIZE_FULL); / Put a CameraPreviewData at the first position. mWrappedDataAdapter = new FixedFirstDataAdapter( new CameraDataAdapter(new ColorDrawable( getResources().getColor(R.color.photo_placeholder), mCameraPreviewData); setModuleFromIndex(moduleIndex); mCurrentModule.init(this, mCameraModuleRootView);,该函数主要设置activity视图，并根据传过来的intent来判读改启动photomodule还是videomodule，当从launcher启动的时候moduleIndex肯定是0，所以会调用mCurrentModule = new PhotoModule();新建一个PhotoModule对象，该对象就是负责拍照相关的操作。Step2：PhotoModule()，对象创建之后，并没有做实质性的动作，我们接着往下看Step3:mCurrentModule.init(this,mCameraModuleRootView); mCurrentModule就是PhotoModule类的一个实例，public void init(CameraActivity activity, View parent) mActivity = activity; mRootView = parent; mUI = new PhotoUI(activity, this, parent); mPreferences = new ComboPreferences(mActivity); CameraSettings.upgradeGlobalPreferences(mPreferences.getGlobal(); mCameraId = getPreferredCameraId(mPreferences); mContentResolver = mActivity.getContentResolver(); / Surface texture is from camera screen nail and startPreview needs it. / This must be done before startPreview. mIsImageCaptureIntent = isImageCaptureIntent(); mPreferences.setLocalId(mActivity, mCameraId); CameraSettings.upgradeLocalPreferences(mPreferences.getLocal(); / we need to reset exposure for the preview resetExposureCompensation(); initializeControlByIntent(); mQuickCapture = mActivity.getIntent().getBooleanExtra(EXTRA_QUICK_CAPTURE, false); mLocationManager = new LocationManager(mActivity, mUI); mSensorManager = (SensorManager)(mActivity.getSystemService(Context.SENSOR_SERVICE); brightnessProgressBar = (ProgressBar)mRootView.findViewById(R.gress); if (brightnessProgressBar instanceof SeekBar) SeekBar seeker = (SeekBar) brightnessProgressBar; seeker.setOnSeekBarChangeListener(mSeekListener); brightnessProgressBar.setMax(MAXIMUM_BRIGHTNESS); brightnessProgressBar.setProgress(mbrightness); skinToneSeekBar = (SeekBar) mRootView.findViewById(R.id.skintoneseek); skinToneSeekBar.setOnSeekBarChangeListener(mskinToneSeekListener); skinToneSeekBar.setVisibility(View.INVISIBLE); Title = (TextView)mRootView.findViewById(R.id.skintonetitle); RightValue = (TextView)mRootView.findViewById(R.id.skintoneright); LeftValue = (TextView)mRootView.findViewById(R.id.skintoneleft); Storage.setSaveSDCard( mPreferences.getString(CameraSettings.KEY_CAMERA_SAVEPATH, 0).equals(1); 刚才介绍过Photomodule是负责camera照相功能的，主要协调界面的显示，参数的配置，方便用户根据自己的爱好来设置相关参数。参数View parent，是拍照界面的根节点， 即在cameraactivity中inflate 的R.layout.camera的camera_app_root视图。Init函数中做了很多重要的工作。创建UI视图，初始化基本参数，Step4：new PhotoUI(activity, this, parent)视图的真正创建是在PhotoUI对象中，我们接着往下看 public PhotoUI(CameraActivity activity, PhotoController controller, View parent) mActivity = activity; mController = controller; mRootView = parent; mActivity.getLayoutInflater().inflate(R.layout.photo_module, (ViewGroup) mRootView, true); mRenderOverlay = (RenderOverlay) mRootView.findViewById(R.id.render_overlay); mFlashOverlay = mRootView.findViewById(R.id.flash_overlay); mPreviewCover = mRootView.findViewById(R.id.preview_cover); / display the view mTextureView = (TextureView) mRootView.findViewById(R.id.preview_content); mTextureView.setSurfaceTextureListener(this); mTextureView.addOnLayoutChangeListener(mLayoutListener); initIndicators(); mShutterButton = (ShutterButton) mRootView.findViewById(R.id.shutter_button); mSwitcher = (ModuleSwitcher) mRootView.findViewById(R.id.camera_switcher); mSwitcher.setCurrentIndex(ModuleSwitcher.PHOTO_MODULE_INDEX); mSwitcher.setSwitchListener(mActivity); mMenuButton = mRootView.findViewById(R.id.menu); ViewStub faceViewStub = (ViewStub) mRootView .findViewById(R.id.face_view_stub); if (faceViewStub != null) faceViewStub.inflate(); mFaceView = (FaceView) mRootView.findViewById(R.id.face_view); setSurfaceTextureSizeChangedListener(mFaceView); mCameraControls = (CameraControls) mRootView.findViewById(R.id.camera_controls); mAnimationManager = new AnimationManager(); mOrientationResize = false; mPrevOrientationResize = false; 函数首先inflate R.layout.photo_module视图，挂在mRootView节点下，mRootView即是R.layout.camera中的camera_app_root视图，他是photomodule的根视图。photo_module这个视图包括了其他的一些重要视图，其中比较重要的几个mTextureView，mShutterButton，mSwitcher，faceViewStub，mCameraControls，mMenuButton等mTextureView：是TextureView控件，和surfaceview功能差不多，只是实现机制不同，都是用来显示流媒体的。Camera preview数据就在此显示mCameraControls：是个容器，包裹mShutterButton，mSwitcher，PieMenuButton，等控件mShutterButton：拍照按钮，mSwitcher：模式切换，faceViewStub脸部扑捉。mMenuButton：设置参数相关的step5：cameraactivity.onresume()界面和参数的初始化工作完成之后，camera activity进去resume状态,public void onResume() mOrientationListener.enable(); mCurrentModule.onResumeBeforeSuper(); super.onResume(); mCurrentModule.onResumeAfterSuper(); setSwipingEnabled(true); . 这里掉用了一个重要的函数mCurrentModule.onResumeAfterSuper()；到目前为止我们还没有看到camera设备被打开的过程，什么原因，以前在oncreate的时候就打开了camera设备，难道是我们在前面分析的时候漏掉了，客官别急，切往下看。Step6，mCurrentModule.onResumeAfterSuper()调用这个函数之后，又进入到photomodule对象中了，我们来看一下具体实现public void onResumeAfterSuper() String action = mActivity.getIntent().getAction(); if (MediaStore.INTENT_ACTION_STILL_IMAGE_CAMERA.equals(action) | MediaStore.INTENT_ACTION_STILL_IMAGE_CAMERA_SECURE.equals(action) Log.v(TAG, On resume, from lock screen.); mHandler.postDelayed(new Runnable() public void run() onResumeTasks(); , ON_RESUME_TASKS_DELAY_MSEC); else Log.v(TAG, On resume.); onResumeTasks(); mHandler.post(new Runnable() Override public void run() mActivity.updateStorageSpaceAndHint(); );函数先根据action类型做不同的处理，最终都会调用onResumeTasks函数。Step7：onResumeTasks()；private void onResumeTasks() if (mOpenCameraFail | mCameraDisabled) return; mJpegPictureCallbackTime = 0; mZoomValue = 0; resetExposureCompensation(); if (!prepareCamera() / Camera failure. return; 函数接着调用prepareCamera进一步启动camera设备Step8：prepareCamera()private boolean prepareCamera() mCameraDevice = CameraUtil.openCamera( mActivity, mCameraId, mHandler, mActivity.getCameraOpenErrorCallback(); if (mCameraDevice = null) Log.e(TAG, Failed to open camera: + mCameraId); return false; mParameters = mCameraDevice.getParameters(); initializeCapabilities(); if (mFocusManager = null) initializeFocusManager(); setCameraParameters(UPDATE_PARAM_ALL); mHandler.sendEmptyMessage(CAMERA_OPEN_DONE); mCameraPreviewParamsReady = true; startPreview(); mOnResumeTime = SystemClock.uptimeMillis(); checkDisplayRotation(); return true; 这个是很重要的函数，函数先调用CameraUtil.openCamera来获取camera设备，CameraUtil.openCamera我们在上一篇文章中介绍过了，这里不做介绍了。获取到camera设备后，接着设置camera初始化参数，最后调用startPreview();启动预览。在启动预览的时候mHandler.sendEmptyMessage(CAMERA_OPEN_DONE);向mHandler发送了一个CAMERA_OPEN_DONE消息。Camera setting的部分测初始化是在这个阶段完成的。Step10：private void onCameraOpened() View root = mUI.getRootView(); int width = root.getWidth(); int height = root.getHeight(); mFocusManager.setPreviewSize(width, height); openCameraCommon(); resizeForPreviewAspectRatio(); 该函数还是比较简单的，设置mFocusManager区域大小，调用openCameraCommon进一步操作cameraStep11：openCameraCommon();private void openCameraCommon() loadCameraPreferences(); mUI.onCameraOpened(mPreferenceGroup, mPreferences, mParameters, this); if (mIsImageCaptureIntent) mUI.overrideSettings(CameraSettings.KEY_CAMERA_HDR_PLUS, mActivity.getString(R.string.setting_off_value); updateCameraSettings(); showTapToFocusToastIfNeeded();函数首先调用loadCameraPreferences函数，来加载默认初始数据R.xml.camera_preferences，将这些初始数据加载到内存中，最终保存在mPreferenceGroup变量中，被后面的UI空间使用。Step14：mUI.onCameraOpened(mPreferenceGroup, mPreferences, mParameters, this);加载完初始数据之后，下一步便是创建必要的UI控件public void onCameraOpened(PreferenceGroup prefGroup, ComboPreferences prefs, Camera.Parameters params, OnPreferenceChangedListener listener) if (mPieRenderer = null) mPieRenderer = new PieRenderer(mA