Android TV Input Framework(TIF)--2 构建TV input list

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本文详细解析了TvInputManagerService的工作原理，包括其构造方法、初始化过程及如何管理不同类型的电视输入信号。深入探讨了TvInputService与TvInputManagerService之间的交互流程。

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TvInputManagerService管理着系统的各种输入，TV Input主要分为三种类型：

hardware input:主要包含TV内建的各种输入端口，比如tuner、component, composite, hdmi。
非hardware input: 视频点播等非内建的硬件端口属于这种类型。
HDMI logic input:带有HDMI CEC的设备属于这种类型。

TvInputManagerService由SystemServer创建，我们先看看它的构造方法

  public TvInputManagerService(Context context) {
        super(context);
        ...
        mTvInputHardwareManager = new TvInputHardwareManager(context, new HardwareListener());

        synchronized (mLock) {
            mUserStates.put(mCurrentUserId, new UserState(mContext, mCurrentUserId));
        }
    }

在构造方法中会创建一下TvInputHardwareManager实例，并传入一个HardwareListener实例给TvInputHardwareManager。TvInputHardwareManager通过TvInputHal来获取TV硬件输入的各种状态，并通过HardwareListener通知TvInputManagerService。

class TvInputHardwareManager implements TvInputHal.Callback

public interface Callback {
        public void onDeviceAvailable(
                TvInputHardwareInfo info, TvStreamConfig[] configs);
        public void onDeviceUnavailable(int deviceId);
        public void onStreamConfigurationChanged(int deviceId, TvStreamConfig[] configs);
        public void onFirstFrameCaptured(int deviceId, int streamId);
    }

 public TvInputHardwareManager(Context context, Listener listener) {
        mContext = context;
        mListener = listener;
        ...
        mHal.init();
    }

TvInputHardwareManager实现了TvInputHal.Callback接口，在构造方法中调用mHal.init()对TvInputHal进行初始化，在TvInputHal初始化过程中，所有TV内建的Input都会通过onDeviceAvailable通知给TvInputHardWareManager,我们看一下onDeviceAvailable的实现：

<code class="hljs r has-numbering">  public void onDeviceAvailable(TvInputHardwareInfo info, TvStreamConfig[] configs) {
        synchronized (mLock) {
            <span class="hljs-keyword">...</span>
            buildHardwareListLocked();
            mHandler.obtainMessage(
                    ListenerHandler.HARDWARE_DEVICE_ADDED, <span class="hljs-number">0</span>, <span class="hljs-number">0</span>, info).sendToTarget();
            <span class="hljs-keyword">...</span>
            }
        }
    }</code>

onDeviceAvailable会调用buildHardwareListLocked把Tv Input的信息放入一个链表，TV Input的信息用TvInputHardwareInfo类表示，

<code class="hljs cs has-numbering"><span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">buildHardwareListLocked</span>() {
        mHardwareList.clear();
        <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>; i < mConnections.size(); ++i) {
            mHardwareList.add(mConnections.valueAt(i).getHardwareInfoLocked());
        }
    }</code>

然后通过mHandler.obtainMessage(ListenerHandler.HARDWARE_DEVICE_ADDED, 0, 0, info).sendToTarget()发送到handler线程处理，

<code class="hljs r has-numbering"> public final void handleMessage(Message msg) {
            <span class="hljs-keyword">switch</span> (msg.what) {
                <span class="hljs-keyword">...</span>
                case HARDWARE_DEVICE_ADDED: {
                    TvInputHardwareInfo info = (TvInputHardwareInfo) msg.obj;
                    mListener.onHardwareDeviceAdded(info);
                    <span class="hljs-keyword">break</span>;
                }
                <span class="hljs-keyword">...</span></code>

还记得TvInputManagerService在创建TvInputHardwareManager的时候传入的HardwareListener吗？它就是mListener, HardwareListener的onHardwareDeviceAdded会被调用，

<code class="hljs java has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onHardwareDeviceAdded</span>(TvInputHardwareInfo info) {
            <span class="hljs-keyword">synchronized</span> (mLock) {
                UserState userState = getUserStateLocked(mCurrentUserId);
                <span class="hljs-comment">// Broadcast the event to all hardware inputs.</span>
                <span class="hljs-keyword">for</span> (ServiceState serviceState : userState.serviceStateMap.values()) {
                    <span class="hljs-keyword">if</span> (!serviceState.isHardware || serviceState.service == <span class="hljs-keyword">null</span>) <span class="hljs-keyword">continue</span>;
                    <span class="hljs-keyword">try</span> {
                        serviceState.service.notifyHardwareAdded(info);
                    } <span class="hljs-keyword">catch</span> (RemoteException e) {
                        Slog.e(TAG, <span class="hljs-string">"error in notifyHardwareAdded"</span>, e);
                    }
                }
            }
        }</code>

到目前为止，我们只是对TvInputManagerService的构造方法进行分析，userState.serviceStateMap还是空的，所以这个时候onHardwareDeviceAdded被调用其实什么事情都没有做。

我们接着分析TvInputManagerService的初始化过程：

<code class="hljs java has-numbering"> <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">onBootPhase</span>(<span class="hljs-keyword">int</span> phase) {
        <span class="hljs-keyword">if</span> (phase == SystemService.PHASE_SYSTEM_SERVICES_READY) {
            registerBroadcastReceivers();
        } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (phase == SystemService.PHASE_THIRD_PARTY_APPS_CAN_START) {
            <span class="hljs-keyword">synchronized</span> (mLock) {
                buildTvInputListLocked(mCurrentUserId, <span class="hljs-keyword">null</span>);
                buildTvContentRatingSystemListLocked(mCurrentUserId);
            }
        }
        mTvInputHardwareManager.onBootPhase(phase);
    }</code>

当第三方的app可以启动的时候，即phase == SystemService.PHASE_THIRD_PARTY_APPS_CAN_START，调用buildTvInputListLocked开始构建Tv Input List。

<code class="hljs cs has-numbering"><span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">buildTvInputListLocked</span>(<span class="hljs-keyword">int</span> userId, String[] updatedPackages) {
        UserState userState = getUserStateLocked(userId);
        userState.packageSet.clear();

        <span class="hljs-keyword">if</span> (DEBUG) Slog.d(TAG, <span class="hljs-string">"buildTvInputList"</span>);
        PackageManager pm = mContext.getPackageManager();
        List<ResolveInfo> services = pm.queryIntentServices(
                <span class="hljs-keyword">new</span> Intent(TvInputService.SERVICE_INTERFACE),
                PackageManager.GET_SERVICES | PackageManager.GET_META_DATA);                       ---<<span class="hljs-number">1</span>>
        List<TvInputInfo> inputList = <span class="hljs-keyword">new</span> ArrayList<TvInputInfo>();
        <span class="hljs-keyword">for</span> (ResolveInfo ri : services) {
            ServiceInfo si = ri.serviceInfo;
            <span class="hljs-keyword">if</span> (!android.Manifest.permission.BIND_TV_INPUT.equals(si.permission)) {
                Slog.w(TAG, <span class="hljs-string">"Skipping TV input "</span> + si.name + <span class="hljs-string">": it does not require the permission "</span>
                        + android.Manifest.permission.BIND_TV_INPUT);
                <span class="hljs-keyword">continue</span>;
            }
            ComponentName component = <span class="hljs-keyword">new</span> ComponentName(si.packageName, si.name);
            <span class="hljs-keyword">if</span> (hasHardwarePermission(pm, component)) {
                ServiceState serviceState = userState.serviceStateMap.<span class="hljs-keyword">get</span>(component);
                <span class="hljs-keyword">if</span> (serviceState == <span class="hljs-keyword">null</span>) {
                    <span class="hljs-comment">// We see this hardware TV input service for the first time; we need to</span>
                    <span class="hljs-comment">// prepare the ServiceState object so that we can connect to the service and</span>
                    <span class="hljs-comment">// let it add TvInputInfo objects to mInputList if there's any.</span>
                    serviceState = <span class="hljs-keyword">new</span> ServiceState(component, userId);                     ---<<span class="hljs-number">2</span>>
                    userState.serviceStateMap.put(component, serviceState);
                    updateServiceConnectionLocked(component, userId);    ---<<span class="hljs-number">3</span>>
                } <span class="hljs-keyword">else</span> {
                    inputList.addAll(serviceState.inputList);            ---<<span class="hljs-number">4</span>>
                }
            } <span class="hljs-keyword">else</span> {
                <span class="hljs-keyword">try</span> {
                    inputList.add(TvInputInfo.createTvInputInfo(mContext, ri));---<<span class="hljs-number">5</span>>
                } <span class="hljs-keyword">catch</span> (XmlPullParserException | IOException e) {
                    Slog.e(TAG, <span class="hljs-string">"failed to load TV input "</span> + si.name, e);
                    <span class="hljs-keyword">continue</span>;
                }
            }
            userState.packageSet.add(si.packageName);
        }

        Map<String, TvInputState> inputMap = <span class="hljs-keyword">new</span> HashMap<String, TvInputState>();             ---<<span class="hljs-number">6</span>>
        <span class="hljs-keyword">for</span> (TvInputInfo info : inputList) {
            <span class="hljs-keyword">if</span> (DEBUG) {
                Slog.d(TAG, <span class="hljs-string">"add "</span> + info.getId());
            }
            TvInputState state = userState.inputMap.<span class="hljs-keyword">get</span>(info.getId());
            <span class="hljs-keyword">if</span> (state == <span class="hljs-keyword">null</span>) {
                state = <span class="hljs-keyword">new</span> TvInputState();     
            }
            state.info = info;
            inputMap.put(info.getId(), state);       
        }

        <span class="hljs-keyword">for</span> (String inputId : inputMap.keySet()) {
            <span class="hljs-keyword">if</span> (!userState.inputMap.containsKey(inputId)) {              ---<<span class="hljs-number">7</span>>
                notifyInputAddedLocked(userState, inputId);
            } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (updatedPackages != <span class="hljs-keyword">null</span>) {
                <span class="hljs-comment">// Notify the package updates</span>
                ComponentName component = inputMap.<span class="hljs-keyword">get</span>(inputId).info.getComponent();
                <span class="hljs-keyword">for</span> (String updatedPackage : updatedPackages) {
                    <span class="hljs-keyword">if</span> (component.getPackageName().equals(updatedPackage)) {
                        updateServiceConnectionLocked(component, userId);
                        notifyInputUpdatedLocked(userState, inputId);
                        <span class="hljs-keyword">break</span>;
                    }
                }
            }
        }

        <span class="hljs-keyword">for</span> (String inputId : userState.inputMap.keySet()) {
            <span class="hljs-keyword">if</span> (!inputMap.containsKey(inputId)) {    ---<<span class="hljs-number">8</span>>
                TvInputInfo info = userState.inputMap.<span class="hljs-keyword">get</span>(inputId).info;
                ServiceState serviceState = userState.serviceStateMap.<span class="hljs-keyword">get</span>(info.getComponent());
                <span class="hljs-keyword">if</span> (serviceState != <span class="hljs-keyword">null</span>) {
                    abortPendingCreateSessionRequestsLocked(serviceState, inputId, userId);
                }
                notifyInputRemovedLocked(userState, inputId);
            }
        }

        userState.inputMap.clear();
        userState.inputMap = inputMap;               ---<<span class="hljs-number">9</span>>
    }</code>

这个方法比较长,关键行标上了序号,下面逐一解释:

1、查找所有的package中的service,如果package的service在AndroidManifest.xml中声明了如下属性：

<code class="hljs avrasm has-numbering"><span class="hljs-label">android:</span>permission=<span class="hljs-string">"android.permission.BIND_TV_INPUT"</span></code>

那么就认为这个service代表一种Tv Input，这些service都继承自TvInputService。对于TV内建的输入端口，还要在package的AndroidManifest.xml声明

<code class="hljs xml has-numbering"><span class="hljs-tag"><<span class="hljs-title">uses-permission</span> <span class="hljs-attribute">android:name</span>=<span class="hljs-value">"android.permission.TV_INPUT_HARDWARE"</span> /></span></code>

2、对于内建的硬件输入端口，TvInputManangerService会创建对应的ServiceState实例，并跟对应的Service建立连接，

<code class="hljs cs has-numbering">  <span class="hljs-keyword">private</span> <span class="hljs-title">ServiceState</span>(ComponentName component, <span class="hljs-keyword">int</span> userId) {
            <span class="hljs-keyword">this</span>.component = component;
            <span class="hljs-keyword">this</span>.connection = <span class="hljs-keyword">new</span> InputServiceConnection(component, userId);
            <span class="hljs-keyword">this</span>.isHardware = hasHardwarePermission(mContext.getPackageManager(), component);
        }</code>

注意this.connection = new InputServiceConnection(component, userId)，稍后会用到。

<code class="hljs r has-numbering"> private void updateServiceConnectionLocked(ComponentName component, int userId) {
     <span class="hljs-keyword">...</span>
            Intent i = new Intent(TvInputService.SERVICE_INTERFACE).setComponent(component);
            serviceState.bound = mContext.bindServiceAsUser(
                    i, serviceState.connection, Context.BIND_AUTO_CREATE, new UserHandle(userId));
       <span class="hljs-keyword">...</span>
    }</code>

3.在updateServiceConnectionLocked中通过Intent跟service建立连接，这个时候inputList是空的，buildTvInputListLocked继续执行返回。当跟service连接成功以后，serviceState.connection.onServiceConnected会被回调，就是前面说的InputServiceConnection.onServiceConnected。

<code class="hljs r has-numbering">public void onServiceConnected(ComponentName component, IBinder service) {
          <span class="hljs-keyword">...</span>
                // Register a callback, <span class="hljs-keyword">if</span> we need to.
                <span class="hljs-keyword">if</span> (serviceState.isHardware && serviceState.callback == null) {
                    serviceState.callback = new ServiceCallback(mComponent, mUserId);
                    <span class="hljs-keyword">try</span> {
                        serviceState.service.registerCallback(serviceState.callback);
                    } catch (RemoteException e) {
                        Slog.e(TAG, <span class="hljs-string">"error in registerCallback"</span>, e);
                    }
                }
               <span class="hljs-keyword">...</span>
                <span class="hljs-keyword">if</span> (serviceState.isHardware) {
                    List<TvInputHardwareInfo> hardwareInfoList =
                            mTvInputHardwareManager.getHardwareList();
                    <span class="hljs-keyword">for</span> (TvInputHardwareInfo hardwareInfo : hardwareInfoList) {
                        <span class="hljs-keyword">try</span> {
                            serviceState.service.notifyHardwareAdded(hardwareInfo);
                        } catch (RemoteException e) {
                            Slog.e(TAG, <span class="hljs-string">"error in notifyHardwareAdded"</span>, e);
                        }
                    }

                    List<HdmiDeviceInfo> deviceInfoList =
                            mTvInputHardwareManager.getHdmiDeviceList();
                    <span class="hljs-keyword">for</span> (HdmiDeviceInfo deviceInfo : deviceInfoList) {
                        <span class="hljs-keyword">try</span> {
                            serviceState.service.notifyHdmiDeviceAdded(deviceInfo);
                        } catch (RemoteException e) {
                            Slog.e(TAG, <span class="hljs-string">"error in notifyHdmiDeviceAdded"</span>, e);
                        }
                    }
                }
            }
        }</code>

接着会向Service注册callback,后面会用到。然后通过mTvInputHardwareManager.getHardwareList获取之前初始化的时候保存的Hardware list，调用service的notifyHardwareAdded方法，我们看一下TvInputService的notifyHardwareAdded实现：

<code class="hljs cs has-numbering"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">notifyHardwareAdded</span>(TvInputHardwareInfo hardwareInfo) {
                mServiceHandler.obtainMessage(ServiceHandler.DO_ADD_HARDWARE_TV_INPUT,
                        hardwareInfo).sendToTarget();
            }</code>

通知Handler线程DO_ADD_HARDWARE_TV_INPUT，

<code class="hljs r has-numbering">public final void handleMessage(Message msg) {
            <span class="hljs-keyword">switch</span> (msg.what) {
            <span class="hljs-keyword">...</span>
            case DO_ADD_HARDWARE_TV_INPUT: {
                    TvInputHardwareInfo hardwareInfo = (TvInputHardwareInfo) msg.obj;
                    TvInputInfo inputInfo = onHardwareAdded(hardwareInfo);
                    <span class="hljs-keyword">if</span> (inputInfo != null) {
                        broadcastAddHardwareTvInput(hardwareInfo.getDeviceId(), inputInfo);
                    }
                    <span class="hljs-keyword">return</span>;
                }
                <span class="hljs-keyword">...</span></code>

然后service的onHardwareAdded方法被调用，并返回TvInputInfo，这代表一个TV Input，然后通过broadcastAddHardwareTvInput通知TvInputManagerService,

<code class="hljs cs has-numbering"> <span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">broadcastAddHardwareTvInput</span>(<span class="hljs-keyword">int</span> deviceId, TvInputInfo inputInfo) {
            <span class="hljs-keyword">int</span> n = mCallbacks.beginBroadcast();
            <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i = <span class="hljs-number">0</span>; i < n; ++i) {
                <span class="hljs-keyword">try</span> {
                    mCallbacks.getBroadcastItem(i).addHardwareTvInput(deviceId, inputInfo);
                } <span class="hljs-keyword">catch</span> (RemoteException e) {
                    Log.e(TAG, <span class="hljs-string">"Error while broadcasting."</span>, e);
                }
            }
            mCallbacks.finishBroadcast();
        }</code>

我们在跟service建立连接以后，注册了callback，callback的addHardwareTvInput被调用，我们看一下TvInputManagerService中addHardwareTvInput的实现,

<code class="hljs java has-numbering"> <span class="hljs-keyword">private</span> <span class="hljs-keyword">void</span> <span class="hljs-title">addTvInputLocked</span>(TvInputInfo inputInfo) {
            ServiceState serviceState = getServiceStateLocked(mComponent, mUserId);
            serviceState.inputList.add(inputInfo);
            buildTvInputListLocked(mUserId, <span class="hljs-keyword">null</span>);
        }

        <span class="hljs-annotation">@Override</span>
        <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">addHardwareTvInput</span>(<span class="hljs-keyword">int</span> deviceId, TvInputInfo inputInfo) {
            ensureHardwarePermission();
            ensureValidInput(inputInfo);
            <span class="hljs-keyword">synchronized</span> (mLock) {
                mTvInputHardwareManager.addHardwareTvInput(deviceId, inputInfo);
                addTvInputLocked(inputInfo);
            }
        }</code>

addHardwareTvInput会调用addTvInputLocked，addTvInputLocked把TvInputInfo存入serviceState.inputList，接着调用buildTvInputListLocked重新构建Tv input list。

4.再次调用buildTvInputListLocked的时候，serviceState不为null，把serviceState.inputList放入到inputList。
5. 如果不是TV内建的硬件Input,直接创建TvInputInfo并放入InputList。
6. 每一个Tv Input都对应一个TvInputState，通过inputId在inputMap中索引。
7. 如果新构建的inputMap中的inputId在userState.inputMap中没有，表明这个TV input是新增加的，如果TV app有注册callback，那么TV app的onInputAdded会被调用。
8. 如果userState.inputMap中的inputId在新构建的inputMap中没有，表明这个TV Input被移除，如果TV app有注册callback，那么TV app的onInputRemoved会被调用。
9. userState.inputMap被新构建的inputMap替换，至此TV input list构建完成。