com.android.camera.Camera.java，主要的實現Activity，繼承於ActivityBase。
ActivityBase
在ActivityBase中執行流程：
- onCreate中進行判斷是否是平板；
- onResume中判斷是否鎖屏，鎖屏&camera不存在時候，mOnResumePending置為true，否則置為false並執行doOnResume；
- onWindowFocusChanged中判斷是否獲取到焦點&mOnResumePending，滿足的話執行doOnResume；
- onPause中將mOnResumePending置為false；
Camera.java
接下來分析Camera.java，執行流程：
1、onCreate
// 獲得攝像頭的數量，前置和后置 getPreferredCameraId(); // 獲得對焦設置eg：連續對焦或者其它 String[] defaultFocusModes = getResources().getStringArray(R.array.pref_camera_focusmode_default_array); //實例化Focus管理對象 mFocusManager = new FocusManager(mPreferences, defaultFocusModes); // 開啟線程來啟動攝像頭 mCameraOpenThread.start(); // 是否是第三方應用啟動拍照功能 mIsImageCaptureIntent = isImageCaptureIntent(); // 設置UI布局文件 setContentView(R.layout.camera); if (mIsImageCaptureIntent) { // 當第三方其送拍照，需要顯示不同的UI，比如取消鍵盤 mReviewDoneButton = (Rotatable) findViewById(R.id.btn_done); mReviewCancelButton = (Rotatable) findViewById(R.id.btn_cancel); findViewById(R.id.btn_cancel).setVisibility(View.VISIBLE); } else { // 反之顯示縮略圖 mThumbnailView = (RotateImageView) findViewById(R.id.thumbnail); mThumbnailView.enableFilter(false); mThumbnailView.setVisibility(View.VISIBLE); } // 一個能旋轉的dialog.比如相機設置的dialog,這個類實現了旋轉的父類 mRotateDialog = new RotateDialogController(this, R.layout.rotate_dialog); // 設置camera的ID，寫道SharedPreference中 mPreferences.setLocalId(this, mCameraId); // 更新preference CameraSettings.upgradeLocalPreferences(mPreferences.getLocal()); // 獲得相機數 mNumberOfCameras = CameraHolder.instance().getNumberOfCameras(); // 貌似是獲得是否是快速拍照 mQuickCapture = getIntent().getBooleanExtra(EXTRA_QUICK_CAPTURE, false); // 為當前的preview重置曝光值 resetExposureCompensation(); // 隱藏系統導航欄等 Util.enterLightsOutMode(getWindow()); //SurfaceView SurfaceView preview = (SurfaceView) findViewById(R.id.camera_preview); SurfaceHolder holder = preview.getHolder(); holder.addCallback(this); holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); try { // 這個join語句就是為了保證openCamera的線程執行完后，當前的線程才開始運行。主要是為了確保camera設備被打開了 mCameraOpenThread.join(); // 線程執行完后置為空來讓系統回收資源 mCameraOpenThread = null; if (mOpenCameraFail) { // 打開camera失敗，顯示“無法連接到相機” Util.showErrorAndFinish(this, R.string.cannot_connect_camera); return; } else if (mCameraDisabled) { // 由於安全政策限制，相機已被停用 Util.showErrorAndFinish(this, R.string.camera_disabled); return; } } catch (InterruptedException ex) { // ignore } //開啟顯示的子線程 mCameraPreviewThread.start(); if (mIsImageCaptureIntent) { //如果是第三方開啟的 ，setupCaptureParams 設置拍照的參數 setupCaptureParams(); } else { //設置ModePicker mModePicker = (ModePicker) findViewById(R.id.mode_picker); mModePicker.setVisibility(View.VISIBLE); mModePicker.setOnModeChangeListener(this); mModePicker.setCurrentMode(ModePicker.MODE_CAMERA); } mZoomControl = (ZoomControl) findViewById(R.id.zoom_control); mOnScreenIndicators = (Rotatable) findViewById(R.id.on_screen_indicators); mLocationManager = new LocationManager(this, this); //攝像頭ID mBackCameraId = CameraHolder.instance().getBackCameraId(); mFrontCameraId = CameraHolder.instance().getFrontCameraId(); // 在startPreview里面有notify方法 synchronized (mCameraPreviewThread) { try { mCameraPreviewThread.wait(); } catch (InterruptedException ex) { // ignore } } // 初始化各種控制按鈕 initializeIndicatorControl(); //初始化拍照聲音 mCameraSound = new CameraSound(); try { //確保顯示 mCameraPreviewThread.join(); } catch (InterruptedException ex) { // ignore } mCameraPreviewThread = null;
2、surfaceCreated
啥都沒做
3、surfaceChanged
// 確保在holder中有surface if (holder.getSurface() == null) { Log.d(TAG, "holder.getSurface() == null"); return; } // We need to save the holder for later use, even when the mCameraDevice // is null. This could happen if onResume() is invoked after this // function. mSurfaceHolder = holder; if (mCameraDevice == null) return; if (mPausing || isFinishing()) return; // Set preview display if the surface is being created. Preview was // already started. Also restart the preview if display rotation has // changed. Sometimes this happens when the device is held in portrait // and camera app is opened. Rotation animation takes some time and // display rotation in onCreate may not be what we want. if (mCameraState == PREVIEW_STOPPED) { startPreview(); startFaceDetection(); } else { if (Util.getDisplayRotation(this) != mDisplayRotation) { setDisplayOrientation(); } if (holder.isCreating()) { // Set preview display if the surface is being created and preview // was already started. That means preview display was set to null // and we need to set it now. setPreviewDisplay(holder); } } // If first time initialization is not finished, send a message to do // it later. We want to finish surfaceChanged as soon as possible to let // user see preview first. if (!mFirstTimeInitialized) { mHandler.sendEmptyMessage(FIRST_TIME_INIT); } else { initializeSecondTime(); }
如果是第一次加載，則執行mHandler.sendEmptyMessage(FIRST_TIME_INIT); 對應處理的是initializeFirstTime();
/** * 初始化，第一次初始化 * // Snapshots can only be taken after this is called. It should be called * // once only. We could have done these things in onCreate() but we want to * // make preview screen appear as soon as possible. */ private void initializeFirstTime() { if (mFirstTimeInitialized) return; // Create orientation listenter. This should be done first because it // takes some time to get first orientation. mOrientationListener = new MyOrientationEventListener(Camera.this); mOrientationListener.enable(); // Initialize location sevice. boolean recordLocation = RecordLocationPreference.get( mPreferences, getContentResolver()); // 初始化屏幕最上方的標志，比如開啟了曝光值啊，什么的 initOnScreenIndicator(); // 位置服務 mLocationManager.recordLocation(recordLocation); keepMediaProviderInstance(); // 檢查存儲空間和初始化儲存目錄 checkStorage(); // Initialize last picture button. mContentResolver = getContentResolver(); if (!mIsImageCaptureIntent) { // no thumbnail in image capture intent // 初始化縮略圖 initThumbnailButton(); } // Initialize shutter button. // 初始化拍照按鈕並設置監聽事件 mShutterButton = (ShutterButton) findViewById(R.id.shutter_button); mShutterButton.setOnShutterButtonListener(this); mShutterButton.setVisibility(View.VISIBLE); // Initialize focus UI. mPreviewFrame = findViewById(R.id.camera_preview); mPreviewFrame.setOnTouchListener(this); // 聚焦框 mFocusAreaIndicator = (RotateLayout) findViewById(R.id.focus_indicator_rotate_layout); CameraInfo info = CameraHolder.instance().getCameraInfo()[mCameraId]; boolean mirror = (info.facing == CameraInfo.CAMERA_FACING_FRONT); mFocusManager.initialize(mFocusAreaIndicator, mPreviewFrame, mFaceView, this, mirror, mDisplayOrientation); // 初始化一個圖片的保存線程 mImageSaver = new ImageSaver(); // 設置屏幕亮度 Util.initializeScreenBrightness(getWindow(), getContentResolver()); // 注冊SD卡相關的廣播，比如拔出存儲卡什么的 installIntentFilter(); // 初始化縮放UI initializeZoom(); // 更新屏幕上的閃光燈什么的標記 updateOnScreenIndicators(); // 開始面部檢測 startFaceDetection(); // Show the tap to focus toast if this is the first start. // 假如是第一次啟動，提示用戶“觸摸對焦” if (mFocusAreaSupported && mPreferences.getBoolean(CameraSettings.KEY_CAMERA_FIRST_USE_HINT_SHOWN, true)) { // Delay the toast for one second to wait for orientation. mHandler.sendEmptyMessageDelayed(SHOW_TAP_TO_FOCUS_TOAST, 1000); } mFirstTimeInitialized = true; addIdleHandler(); }
如果不是，則執行initializeSecondTime();
/** * // If the activity is paused and resumed, this method will be called in * // onResume. */ private void initializeSecondTime() { // Start orientation listener as soon as possible because it takes // some time to get first orientation. //方向翻轉設置enable，其中包括翻轉的時候的動畫 mOrientationListener.enable(); // Start location update if needed. boolean recordLocation = RecordLocationPreference.get( mPreferences, getContentResolver()); mLocationManager.recordLocation(recordLocation); //設置SD卡廣播 installIntentFilter(); mImageSaver = new ImageSaver(); //初始化Zoom initializeZoom(); //mMediaProviderClient=媒體Provider對象 keepMediaProviderInstance(); //檢查硬盤 checkStorage(); //淡出retake和done的Button hidePostCaptureAlert(); if (!mIsImageCaptureIntent) { //如果不是第三方開啟，則更新縮略圖 updateThumbnailButton(); mModePicker.setCurrentMode(ModePicker.MODE_CAMERA); } }
4、surfaceDestroyed
stopPreview(); mSurfaceHolder = null;