android_brightness_resolving

浅析Brightness的创建和执行流程：

步凑一 系统中packages\apps\Settings\res\xml\display_settings.xml中有添加preference组件：

        <com.android.settings.BrightnessPreference                android:title="@string/brightness"                android:persistent="false"/>

//在自定义BrightnessPreference.java中只发送了一条广播：

public class BrightnessPreference extends Preference {    public BrightnessPreference(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    protected void onClick() {      //发送了一个显示亮度调节对话框的广播    Intent intent = new Intent(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG);     getContext().sendBroadcastAsUser(intent, UserHandle.CURRENT_OR_SELF); }}

步凑二 接收广播并且显示BrightnessDialog菜单的消息是在framework中接收处理的：

public class SettingsUI extends SystemUI {    private static final String TAG = "SettingsUI";    private static final boolean DEBUG = false;    private final Handler mHandler = new Handler();    private BrightnessDialog mBrightnessDialog;    private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {        @Override        public void onReceive(Context context, Intent intent) {            String action = intent.getAction();            if (action.equals(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG)) {                if (DEBUG) Log.d(TAG, "showing brightness dialog");                if (mBrightnessDialog == null) {                   //创建BrightnessDialog实例                    mBrightnessDialog = new BrightnessDialog(mContext);                    mBrightnessDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {                        @Override                        public void onDismiss(DialogInterface dialog) {                            mBrightnessDialog = null;                        }                    });                }                if (!mBrightnessDialog.isShowing()) {                //显示brightnessDialog                    mBrightnessDialog.show();                }            } else {                Log.w(TAG, "unknown intent: " + intent);            }        }    };    public void start() {        //监听ACTION_SHOW_BRIGHTNESS_DIALOG的广播        IntentFilter filter = new IntentFilter();        filter.addAction(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG);        mContext.registerReceiverAsUser(mIntentReceiver, UserHandle.ALL, filter, null, mHandler);    }

步凑三 创建seekbar布局定义的结构层次是：

       1.BrightnessDialog.java
       2.BrightnessDialog.java中创建了quick_settings_brightness_dialog
       3.quick_settings_brightness_dialog中自定义了控件com.android.systemui.settings.ToggleSlider
       4.ToggleSlider.java中真正创建了seekbar控件。
       如下是：BrightnessDialog.java

    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Window window = getWindow();        window.setType(WindowManager.LayoutParams.TYPE_VOLUME_OVERLAY);        window.getAttributes().privateFlags |=                WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS;        window.clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);        window.requestFeature(Window.FEATURE_NO_TITLE);        /*SPRD bug 636829:Don't auto dismiss brightness dialog*/        window.setGravity(Gravity.CENTER_VERTICAL);        setContentView(R.layout.quick_settings_brightness_dialog);        setCanceledOnTouchOutside(true);    }

       如下是quick_settings_brightness_dialog布局文件：

    <TextView        android:id="@+id/tab_switch_container_display"        android:layout_centerVertical="true"        android:layout_gravity="center_horizontal"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:textColor="#ffffffff"        android:textSize="18px"        android:text="@string/label_screen_brightness"/>    <com.android.systemui.settings.ToggleSlider        android:id="@+id/brightness_slider"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="center_vertical"        android:layout_weight="1"        systemui:text="@string/status_bar_settings_auto_brightness_label" />

        如下是：com.android.systemui.settings.ToggleSlider文件  

    public ToggleSlider(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        View.inflate(context, R.layout.status_bar_toggle_slider, this);        final Resources res = context.getResources();        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ToggleSlider,                defStyle, 0);        mToggle = (CompoundButton)findViewById(R.id.toggle);                /* SPRD:Modify Bug 333649, remove brightness auto set @{ */        if (fileIsExists()) {            mToggle.setOnCheckedChangeListener(this);            mToggle.setBackgroundDrawable(res.getDrawable(R.drawable.status_bar_toggle_button));        }        /* @} */        mSlider = (SeekBar)findViewById(R.id.slider);        mSlider.setOnSeekBarChangeListener(this);        mLabel = (TextView)findViewById(R.id.label);        mLabel.setVisibility(GONE);        /* SPRD:Modify Bug 333649, remove brightness auto set @{ */        /* SPRD: Bug 583693 PikeL Feature {@ */        //if (fileIsExists()) {            //mLabel.setText(a.getString(R.styleable.ToggleSlider_text));        //}        /* @} */        a.recycle();    }

    如下是：真正创建了seekbar控件

    <com.android.systemui.settings.ToggleSeekBar        android:id="@+id/slider"        android:layout_width="0dp"        android:layout_height="wrap_content"        android:layout_toEndOf="@id/toggle"        android:layout_centerVertical="true"        android:layout_alignParentStart="true"        android:layout_alignParentEnd="true"        android:paddingStart="20dp"        android:paddingEnd="20dp"        android:paddingTop="12dp"        android:paddingBottom="12dp"        //设置拖动进度条上的拇指图标        android:thumb="@drawable/ic_brightness_thumb_customized"       

步凑四 对亮度的真正调节效果是使用了BrightnessDialog.java中的BrightnessController：

    protected void onStart() {        super.onStart();        mBrightnessController = new BrightnessController(getContext(),                (ImageView) findViewById(R.id.brightness_icon),                (ToggleSlider) findViewById(R.id.brightness_slider));        dismissBrightnessDialog(mBrightnessDialogLongTimeout);        mBrightnessController.addStateChangedCallback(this);

对BrightnessController中的浅析：
在上面onStart中创建了BrightnessDialog对象时构造函数中做了如下操作：

   public BrightnessController(Context context, ImageView icon, ToggleSlider control) {        mContext = context;        mIcon = icon;        mControl = control;        /* SPRD: add to optimize oom for bug 295792 @{ */       //接收SCREEN_BRIGHTNESS_MESSAGE_ID发送过来的消息处理：（保存亮度值的方式二种用到的方法，在下面代码中）        mHandler = new Handler(){            @Override            public void handleMessage(Message msg) {                // TODO Auto-generated method stub                super.handleMessage(msg);                if (msg.what == SCREEN_BRIGHTNESS_MESSAGE_ID) {                    //保存当前的亮度值至Settings.system系统中                    Settings.System.putIntForUser(mContext.getContentResolver(),                            Settings.System.SCREEN_BRIGHTNESS, msg.arg1,                            UserHandle.USER_CURRENT);                }            }        };        /* @} */        mUserTracker = new CurrentUserTracker(mContext) {            @Override            public void onUserSwitched(int newUserId) {                updateMode();                updateSlider();            }        };       //创建观察者模式监控亮屏的模式和亮度值状态，当发生改变时进行更新        mBrightnessObserver = new BrightnessObserver(mHandler);        mBrightnessObserver.startObserving();       //获取PowerManager对象，从而获得亮度的最大值和最小亮度值             PowerManager pm = (PowerManager)context.getSystemService(Context.POWER_SERVICE);        mMinimumBacklight = pm.getMinimumScreenBrightnessSetting();        mMaximumBacklight = pm.getMaximumScreenBrightnessSetting();        mAutomaticAvailable = context.getResources().getBoolean(                com.android.internal.R.bool.config_automatic_brightness_available);       //获取IpowerManager对象        mPower = IPowerManager.Stub.asInterface(ServiceManager.getService("power"));        // Update the slider and mode before attaching the listener so we don't receive the        // onChanged notifications for the initial values.        updateMode();        updateSlider();        control.setOnChangedListener(this);    }

其中ToggleSlider文件中对seekbar控件进行监控事件处理的三个重写的方法：

     //拖动中    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {        if (mListener != null) {            mListener.onChanged(this, mTracking, mToggle.isChecked(), progress);        }    }    //开始拖动    public void onStartTrackingTouch(SeekBar seekBar) {        mTracking = true;        if (mListener != null) {            mListener.onChanged(this, mTracking, mToggle.isChecked(), mSlider.getProgress());        }        mToggle.setChecked(false);    }    //停止拖动    public void onStopTrackingTouch(SeekBar seekBar) {        mTracking = false;        if (mListener != null) {            mListener.onChanged(this, mTracking, mToggle.isChecked(), mSlider.getProgress());        }    }

在BrightnessController.java中实际处理了如下信息：

    public void onChanged(ToggleSlider view, boolean tracking, boolean automatic, int value) {       //设置亮度的设置模式，mode=0表示为手动，mode=1表示自动调节        setMode(automatic ? Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC                : Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);        updateIcon(automatic);        if (!automatic) {            final int val = value + mMinimumBacklight;            //设置屏幕的亮度            setBrightness(val);            // SPRD: fixbug364442 add log for brightness control.            Log.d(TAG, "onChanged : value =" + value + " , mMinimumBacklight =" +                    mMinimumBacklight + " , tracking =" + tracking);            //以下的设置是将屏幕的亮度值保存到settings/system中的两种方式           //方式一：直接putIntForUser            if (!tracking) {                /* SPRD: add to optimize oom for bug 295792 @{                 * @origin: we move it to handlemessage beicause there are too many runnables                 * AsyncTask.execute(new Runnable() {                 * public void run() {                 *            Settings.System.putIntForUser(mContext.getContentResolver(),                 *                    Settings.System.SCREEN_BRIGHTNESS, val,                 *                    UserHandle.USER_CURRENT);                 *        }                 *    });                 */           //方式二：通过handle  发送一个SCREEN_BRIGHTNESS_MESSAGE_ID消息给到接收方处理保存亮度。                mHandler.removeMessages(SCREEN_BRIGHTNESS_MESSAGE_ID);                //发送SCREEN_BRIGHTNESS_MESSAGE_ID消息                mHandler.obtainMessage(SCREEN_BRIGHTNESS_MESSAGE_ID, val, -1).sendToTarget();                /* @} */            }        }        for (BrightnessStateChangeCallback cb : mChangeCallbacks) {            cb.onBrightnessLevelChanged();        }    }

附加：设置屏亮度

    private void setBrightness(int brightness) {        try {            mPower.setTemporaryScreenBrightnessSettingOverride(brightness);        } catch (RemoteException ex) {        }    }

设置亮屏模式：

    private void setMode(int mode) {        Settings.System.putIntForUser(mContext.getContentResolver(),                Settings.System.SCREEN_BRIGHTNESS_MODE, mode,                mUserTracker.getCurrentUserId());    }

时间关系，只能仓促的这样结束了，条理不怎么清晰，看不懂莫怪，还有可能误导大家，写这个就是希望有人能指正我的错误，仅供参考吧！