Android

实际工作中为了fix某个issue，车载应用需要在车机andoid系统退出STR模式(Suspend to RAM)时候执行某个逻辑 解决方案参照anrdoid文档 注册一个CarPowerStateListener回调，重写onStateChanged 方法 在androidManifest.xml中增加以下权限 1 <uses-permission android:name="android.car.permission.CAR_POWER" /> 在业务逻辑中注册CarPowerStateListener 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 import android.car.hardware.power.CarPowerManager; import android.car.hardware.power.CarPowerManager.CarPowerStateListener; public class MyService extends Service { private CarPowerManager mCarPowerManager = null; @override public void onCreate() { super.onCreate(); Car car = Car.CreateCar(this); mCarPowerManager = (CarPowerManager)car.getCarManager(Car.POWER_SERVICE); if(mCarPowerManager!=null) { final CarPowerManager.CarPowerStateListener powerListener = new CarPowerManager.CarPowerStateListener () { @Override public void onStateChanged(int state) { Log.i(TAG, "onStateChanged() state = " + state); if(state==SUSPEND_EXIT) //此时退出STR mode { //do my business } } }; } } @override public void onDestroy() { super.onDestroy(); if(mCarPowerManager!=null) { mCarPowerManager.clearListener(); } } }

应用程序的渲染方式分为两种 按需渲染: 绝大多数应用程序，比如微信/钉钉/QQ，都是这种，当有数据更新才请求重新刷新绘制界面 定频渲染：比如游戏，永远按照固定的频率进行渲染(只有这样，才能模拟出逼真的动画效果) 在android 中，上述两个场景分别用以下两个类 SurfaceView(按需渲染)：直接在UI线程进行渲染，效率低，适用于渲染频率低的应用场景。 GLSurfaceView(定频渲染)：开启一个独立的opengl线程来进行渲染（防止UI线程被阻塞)，每个GLSurfaceView的实例都有一个 GLThread mGLThread 成员 无论是java/C++， opengl绘制流程都一样： 初始化 egl 参数 在一个循环中不断进行帧绘制 类的大体定义如下 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 public class GLSurfaceView extends SurfaceView implements SurfaceHolder.Callback2 { private GLThread mGLThread; //独立的opengl线程进行渲染 private Renderer mRenderer; //自定义的Renderer, 这个Render定义了如何进行渲染 ........ public void setRenderer(Renderer renderer) { ......... mRenderer = renderer; mGLThread = new GLThread(mThisWeakRef); mGLThread.start(); //启动opengl线程 } public void queueEvent(Runnable r) { mGLThread.queueEvent(r); } ......... } public class SurfaceView extends View implements ViewRootImpl.SurfaceChangedCallback { SurfaceControl mSurfaceControl; // 与android系统的的surfacefinger服务进行binder通讯 public void draw(Canvas canvas){ ..... super.draw(canvas); } } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 static class GLThread extends Thread { @Override public void run() { setName("GLThread " + getId()); if (LOG_THREADS) { Log.i("GLThread", "starting tid=" + getId()); } try { guardedRun(); } catch (InterruptedException e) { // fall thru and exit normally } finally { sGLThreadManager.threadExiting(this); } } private void guardedRun() throws InterruptedException { ............. Runnable event = null; while(true){ synchronized (sGLThreadManager) { while (true) { if (mShouldExit) { return; } //pop 一个 event if (! mEventQueue.isEmpty()) { event = mEventQueue.remove(0); break; } if (event != null) { event.run(); // 执行event event = null; continue; } ........... // 初始化egl mEglHelper.createGL(); ........... //onSurfaceCreated mRenderer.onSurfaceCreated(gl, mEglHelper.mEglConfig); if(sizeChanged) //如果view大小发生了变化 { //onSurfaceChanged mRenderer.onSurfaceChanged(gl, w, h); } //绘制 mRenderer.onDrawFrame(gl); ........... } } } } } 自定义Render类 ...