SystemUI之状态栏status icon加载流程

引言

今天我们主要讲的是SystemUI状态栏里面常见的一排icons——status icons，该icons主要用于显示Bluetooth、Location、Headset等等系统状态的icon，表示当前手机蓝牙、定位、耳机等的功能开启了，以达到提示用户的目的。

正文

本文主要从两个方面讲述下status icon功能，主要分为初始化流程和状态显示流程
话不多说，我们开始吧。

初始化流程

首先我们看下状态栏的布局文件 status_bar.xml

<com.android.keyguard.AlphaOptimizedLinearLayout android:id="@+id/system_icon_area"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="horizontal"
            >

            <include layout="@layout/system_icons" />

            <com.android.systemui.statusbar.policy.Clock
                android:id="@+id/clock"
                android:textAppearance="@style/TextAppearance.StatusBar.Clock"
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:singleLine="true"
                android:paddingStart="@dimen/status_bar_clock_starting_padding"
                android:paddingEnd="@dimen/status_bar_clock_end_padding"
                android:gravity="center_vertical|start"
                />
        </com.android.keyguard.AlphaOptimizedLinearLayout>

其中我们今天讲的status_icons就藏身于 system_icons.xml 之中

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/system_icons"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:gravity="center_vertical">

    <com.android.keyguard.AlphaOptimizedLinearLayout android:id="@+id/statusIcons"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:orientation="horizontal"/>

    <include layout="@layout/signal_cluster_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/signal_cluster_margin_start"/>

    <com.android.systemui.BatteryMeterView android:id="@+id/battery"
        android:layout_height="match_parent"
        android:layout_width="wrap_content"
        />
</LinearLayout>

android:id="@+id/statusIcons"出现了，人如其名，它其实是一个自定义的LinearLayout——AlphaOptimizedLinearLayout，这个Viewt也是非常简单的，只是实现了如下方法

    @Override
    public boolean hasOverlappingRendering() {
        return false;
    }

该方法用来标记当前view是否存在过度绘制，存在返回ture，不存在返回false，而api里面默认返回为true，诚然我们status icon是个好同学，不存在过度绘制。

接下来我们看下SystemUI是怎么加载这个AlphaOptimizedLinearLayout

   @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        mStatusBar = (PhoneStatusBarView) view;
        if (savedInstanceState != null && savedInstanceState.containsKey(EXTRA_PANEL_STATE)) {
            mStatusBar.go(savedInstanceState.getInt(EXTRA_PANEL_STATE));
        }
        mDarkIconManager = new DarkIconManager(view.findViewById(R.id.statusIcons));
        Dependency.get(StatusBarIconController.class).addIconGroup(mDarkIconManager);
        mSystemIconArea = mStatusBar.findViewById(R.id.system_icon_area);
        mSignalClusterView = mStatusBar.findViewById(R.id.signal_cluster);
        Dependency.get(DarkIconDispatcher.class).addDarkReceiver(mSignalClusterView);
        // Default to showing until we know otherwise.
        showSystemIconArea(false);
        initEmergencyCryptkeeperText();
    }

在 CollapsedStatusBarFragment.java 中我们见到了初始化，这个类相信有状态栏开发经验的都很熟悉了，与本文相关的代码如下
mDarkIconManager = new DarkIconManager(view.findViewById(R.id.statusIcons));
我们接着看这个DarkIconManager初始化里做了什么

public DarkIconManager(LinearLayout linearLayout) {
            super(linearLayout);
            mIconHPadding = mContext.getResources().getDimensionPixelSize(
                    R.dimen.status_bar_icon_padding);
            mDarkIconDispatcher = Dependency.get(DarkIconDispatcher.class);
        }

public static class IconManager {
        protected final ViewGroup mGroup;
        protected final Context mContext;
        protected final int mIconSize;

        public IconManager(ViewGroup group) {
            mGroup = group;
            mContext = group.getContext();
            mIconSize = mContext.getResources().getDimensionPixelSize(
                    com.android.internal.R.dimen.status_bar_icon_size);
        }

        protected void onIconAdded(int index, String slot, boolean blocked,
                StatusBarIcon icon) {
            addIcon(index, slot, blocked, icon);
        }

        protected StatusBarIconView addIcon(int index, String slot, boolean blocked,
                StatusBarIcon icon) {
            StatusBarIconView view = onCreateStatusBarIconView(slot, blocked);
            view.set(icon);
            mGroup.addView(view, index, onCreateLayoutParams());
            return view;
        } 

        public void onSetIcon(int viewIndex, StatusBarIcon icon) {
            StatusBarIconView view = (StatusBarIconView) mGroup.getChildAt(viewIndex);
            view.set(icon);
        }

    }

在StatusBarIconController.java中可以看到，在onIconAdded--->addIcon两个函数里面实现了AlphaOptimizedLinearLayout子view即icon的增加，onSetIcon可能就是刷新icon状态的，请记住这两张面孔

onIconAdded(int index, String slot, boolean blocked,StatusBarIcon icon)
onSetIcon(int viewIndex, StatusBarIcon icon)

到这里我们就知道了icon添加的流程。
onIconAdded(int index, String slot, boolean blocked,StatusBarIcon icon)
而且在这个函数里面有参数index和slot，我们应该可以猜到，每个icon应该就是对应着代表顺序的index和数据类型为String的slot，那么到底是不是这样呢？index和slot又是从哪里来的呢？我们接着往下看。

在StatusBarIconControllerImpl.java构造函数里我们找到了实现

public StatusBarIconControllerImpl(Context context) {
        super(context.getResources().getStringArray(
                com.android.internal.R.array.config_statusBarIcons));

StatusBarIconControllerImpl的父类是StatusBarIconList

    protected ArrayList<String> mSlots = new ArrayList<>();
    protected ArrayList<StatusBarIcon> mIcons = new ArrayList<>();

    public StatusBarIconList(String[] slots) {
        final int N = slots.length;
        for (int i=0; i < N; i++) {
            mSlots.add(slots[i]);
            mIcons.add(null);
        }
    }

在这里我们就找到了index和slot的出处，原来在初始化的时候就已经定义好了所有的slots，然后从framework中加载出来，index就是string-array中的顺序。

<string-array name="config_statusBarIcons">
        <item><xliff:g id="id">@string/status_bar_rotate</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_headset</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_data_saver</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_managed_profile</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_ime</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_sync_failing</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_sync_active</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_cast</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_hotspot</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_location</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_bluetooth</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_nfc</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_tty</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_speakerphone</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_zen</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_mute</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_volume</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_vpn</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_ethernet</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_wifi</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_mobile</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_airplane</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_cdma_eri</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_data_connection</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_phone_evdo_signal</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_phone_signal</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_battery</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_alarm_clock</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_secure</xliff:g></item>
        <item><xliff:g id="id">@string/status_bar_clock</xliff:g></item>
    </string-array>

    <string translatable="false" name="status_bar_rotate">rotate</string>
    <string translatable="false" name="status_bar_headset">headset</string>
    <string translatable="false" name="status_bar_data_saver">data_saver</string>
    <string translatable="false" name="status_bar_managed_profile">managed_profile</string>
    <string translatable="false" name="status_bar_ime">ime</string>
    <string translatable="false" name="status_bar_sync_failing">sync_failing</string>
    <string translatable="false" name="status_bar_sync_active">sync_active</string>
    <string translatable="false" name="status_bar_cast">cast</string>
    <string translatable="false" name="status_bar_hotspot">hotspot</string>
    <string translatable="false" name="status_bar_location">location</string>
    <string translatable="false" name="status_bar_bluetooth">bluetooth</string>
    <string translatable="false" name="status_bar_nfc">nfc</string>
    <string translatable="false" name="status_bar_tty">tty</string>
    <string translatable="false" name="status_bar_speakerphone">speakerphone</string>
    <string translatable="false" name="status_bar_zen">zen</string>
    <string translatable="false" name="status_bar_mute">mute</string>
    <string translatable="false" name="status_bar_volume">volume</string>
    <string translatable="false" name="status_bar_wifi">wifi</string>
    <string translatable="false" name="status_bar_cdma_eri">cdma_eri</string>
    <string translatable="false" name="status_bar_data_connection">data_connection</string>
    <string translatable="false" name="status_bar_phone_evdo_signal">phone_evdo_signal</string>
    <string translatable="false" name="status_bar_phone_signal">phone_signal</string>
    <string translatable="false" name="status_bar_battery">battery</string>
    <string translatable="false" name="status_bar_alarm_clock">alarm_clock</string>
    <string translatable="false" name="status_bar_secure">secure</string>
    <string translatable="false" name="status_bar_clock">clock</string>
    <string translatable="false" name="status_bar_mobile">mobile</string>
    <string translatable="false" name="status_bar_vpn">vpn</string>
    <string translatable="false" name="status_bar_ethernet">ethernet</string>
    <string translatable="false" name="status_bar_airplane">airplane</string>

好了，到这里我们的第一部分初始化流程就讲完了

状态显示流程

由上面的初始化流程我们可以知道，每个icon都对应了slot，slot数量比较多，我们就挑一个常见的Headset讲下，其他的流程都是大致一样的。

PhoneStatusBarPolicy.java这个类在初始化的时候注册了大量的监听

public PhoneStatusBarPolicy(Context context, StatusBarIconController iconController) {
        mContext = context;
        //  初始化headset的slot
        mSlotHeadset = context.getString(com.android.internal.R.string.status_bar_headset);

        // listen for broadcasts
        IntentFilter filter = new IntentFilter();
        filter.addAction(AudioManager.RINGER_MODE_CHANGED_ACTION);
        filter.addAction(AudioManager.INTERNAL_RINGER_MODE_CHANGED_ACTION);
        //  注册headset状态变化的action
        filter.addAction(AudioManager.ACTION_HEADSET_PLUG);
        filter.addAction(TelephonyIntents.ACTION_SIM_STATE_CHANGED);
        filter.addAction(TelecomManager.ACTION_CURRENT_TTY_MODE_CHANGED);
        filter.addAction(Intent.ACTION_MANAGED_PROFILE_AVAILABLE);
        filter.addAction(Intent.ACTION_MANAGED_PROFILE_UNAVAILABLE);
        filter.addAction(Intent.ACTION_MANAGED_PROFILE_REMOVED);
        mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);

这个类就是完成icon添加和状态监听的地方，然后当收到对应的action变化的时候，更新headset icon

private void updateHeadsetPlug(Intent intent) {
        boolean connected = intent.getIntExtra("state", 0) != 0;
        boolean hasMic = intent.getIntExtra("microphone", 0) != 0;
        if (connected) {
            String contentDescription = mContext.getString(hasMic
                    ? R.string.accessibility_status_bar_headset
                    : R.string.accessibility_status_bar_headphones);
            mIconController.setIcon(mSlotHeadset, hasMic ? R.drawable.ic_headset_mic
                    : R.drawable.ic_headset, contentDescription);
            mIconController.setIconVisibility(mSlotHeadset, true);
        } else {
            mIconController.setIconVisibility(mSlotHeadset, false);
        }
    }

其中主要的方法如下
mIconController.setIcon(mSlotHeadset, hasMic ? R.drawable.ic_headset_mic
: R.drawable.ic_headset, contentDescription);
mIconController.setIconVisibility(mSlotHeadset, true);
这两个函数里面setIcon负责设置icon，而setIconVisibility则根据connected状态设置icon的可见性，下面我们就看下这里面的流程是怎么和初始化流程连接在一起的。

来到StatusBarIconControllerImpl.java这个类中的实现

@Override
    public void setIcon(String slot, int resourceId, CharSequence contentDescription) {
        int index = getSlotIndex(slot);
        StatusBarIcon icon = getIcon(index);
        if (icon == null) {
            icon = new StatusBarIcon(UserHandle.SYSTEM, mContext.getPackageName(),
                    Icon.createWithResource(mContext, resourceId), 0, 0, contentDescription);
            setIcon(slot, icon);
        } else {
            icon.icon = Icon.createWithResource(mContext, resourceId);
            icon.contentDescription = contentDescription;
            handleSet(index, icon);
        }
    }

逻辑很清晰，首先根据slot找到对应的index，然后用index取得对应的icon，诚然第一次的时候，icon == null，所以通过new StatusBarIcon创建一个，然后调用 setIcon(slot, icon)，我们接着往下看

    @Override
    public void setIcon(String slot, StatusBarIcon icon) {
        setIcon(getSlotIndex(slot), icon);
    }

    @Override
    public void setIcon(int index, StatusBarIcon icon) {
        if (icon == null) {
            removeIcon(index);
            return;
        }
        boolean isNew = getIcon(index) == null;
        super.setIcon(index, icon);
        if (isNew) {
            addSystemIcon(index, icon);
        } else {
            handleSet(index, icon);
        }
    }

因为我们之前已经添加了icon，此处icon非空，所以不会走return，但是我们刚才getIcon(index) == null的，所以主要看的是addSystemIcon(index, icon)方法

private void addSystemIcon(int index, StatusBarIcon icon) {
        String slot = getSlot(index);
        int viewIndex = getViewIndex(index);
        boolean blocked = mIconBlacklist.contains(slot);

        mIconLogger.onIconVisibility(getSlot(index), icon.visible);
        mIconGroups.forEach(l -> l.onIconAdded(viewIndex, slot, blocked, icon));
    }

有没有看到一个熟悉的面孔——onIconAdded，对了这个就是我们初始化流程里面StatusBarIconController中添加icon的入口，好了到这里setIcon就添加完毕了。

接着就是setIconVisibility函数了，我们再回到StatusBarIconControllerImpl.java中

public void setIconVisibility(String slot, boolean visibility) {
        int index = getSlotIndex(slot);
        StatusBarIcon icon = getIcon(index);
        if (icon == null || icon.visible == visibility) {
            return;
        }
        icon.visible = visibility;
        handleSet(index, icon);
    }

icon已经创建成功了，icon非空，并且第一次是icon.visible != visibility的,自然就会顺利的走到handleSet(index, icon)

private void handleSet(int index, StatusBarIcon icon) {
        int viewIndex = getViewIndex(index);
        mIconLogger.onIconVisibility(getSlot(index), icon.visible);
        mIconGroups.forEach(l -> l.onSetIcon(viewIndex, icon));
    }

好了又是一个熟悉的面孔——onSetIcon，这个也是我们初始化流程里面StatusBarIconController中setIcon的地方，setIconVisibility也设置完毕了。

到这里，status icon加载流程已经讲完，后面有时间还会讲下notification icon和signal icon的加载流程，敬请关注。

如有什么问题欢迎指正。

本文章已经独家授权ApeClub公众号使用。

SystemUI之状态栏status icon加载流程

引言

正文

初始化流程

状态显示流程

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