Android学习 ——SystemUIService之SettingsUI分析

SettingsUI.java 并不是 “设置” 相关 的  而仅仅是 “亮度设置” 。类名夸大了类作用

还是先从入口start()

public void start() {
        IntentFilter filter = new IntentFilter();
        filter.addAction(Intent.ACTION_SHOW_BRIGHTNESS_DIALOG);
        mContext.registerReceiverAsUser(mIntentReceiver, UserHandle.ALL, filter, null, mHandler);
    }

可见入口仅仅是注册了 ACTION_SHOW_BRIGHTNESS_DIALOG  广播监听，指定了 mIntentReceiver  处理事件

查看mIntentReceiver 实现

    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)) { // 显示亮度控制对话框  广播
                if (DEBUG) Log.d(TAG, "showing brightness dialog");

                if (mBrightnessDialog == null) { // 如果没有创建对话框就生成
                    mBrightnessDialog = new BrightnessDialog(mContext);
                    mBrightnessDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
                        @Override
                        public void onDismiss(DialogInterface dialog) {
                            mBrightnessDialog = null;
                        }
                    });
                }

                if (!mBrightnessDialog.isShowing()) { // 如果没显示就显示对话框
                    mBrightnessDialog.show();
                }

            } else {
                Log.w(TAG, "unknown intent: " + intent);
            }
        }
    };

在事件广播中实现的是对话框的创建，以及显示相关的逻辑

这其中涉及到 BrightnessDialog 类 ，进入该类可知其继承系统的Dialog类 并实现了 BrightnessController.BrightnessStateChangeCallback协议，这里又涉及到BrightnessController暂且不论。

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BrightnessDialog 是视图类，主要作用函数在其初始化函数及生命周期函数中

初始化函数
public BrightnessDialog(Context ctx) {
        super(ctx);
        Resources r = ctx.getResources();
        mBrightnessDialogLongTimeout =
                r.getInteger(R.integer.quick_settings_brightness_dialog_long_timeout);
        mBrightnessDialogShortTimeout =
                r.getInteger(R.integer.quick_settings_brightness_dialog_short_timeout);
    }

在初始化函数中仅仅是设置了长超时时间和短超时时间

onCreate()

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //创建一个窗口
        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);

         setContentView(R.layout.quick_settings_brightness_dialog);
        setCanceledOnTouchOutside(true); // 点击外部消失
    }

在onCreate 函数中 创建了一个窗口，并设置显示对话视图，同时实现点击外界让窗口消失

onStart()

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); 设置当前为状态改变的会回调
    }

在onStart()函数中 实例化对象mBrightnessController(参数 imageview 和 ToggleSlide) ，引入新的自定义类 ToggleSlide，暂且不论

// 执行之前先移除之前的事件，在执行当前事件
    private void dismissBrightnessDialog(int timeout) {
        removeAllBrightnessDialogCallbacks();
        mHandler.postDelayed(mDismissDialogRunnable, timeout);
    }

状态改变的触发函数为

// 正常情况下，弹出后在一定时间内就会自动消失，但是如果用户操作改变了亮度等级，就改变了自动超时
    // 触发的时间，所以先取消之前的定时，在执行新的定时
    public void onBrightnessLevelChanged() {
        dismissBrightnessDialog(mBrightnessDialogShortTimeout);
    }

BrightnessDialog 类是为了管理对话框视图层的显示，消失，时间控制等(mvc 的 v)

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BrightnessController 类

    public BrightnessController(Context context, ImageView icon, ToggleSlider control) {
        mContext = context;
        mIcon = icon;
        mControl = control;
        mHandler = new Handler();

        // 实现抽象类的抽象方法 多用户
        mUserTracker = new CurrentUserTracker(mContext) {
            @Override
            public void onUserSwitched(int newUserId) {
                updateMode();
                updateSlider();
            }
        };

        // 创建一个观察，观察亮度变化
        mBrightnessObserver = new BrightnessObserver(mHandler);
        mBrightnessObserver.startObserving();

        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);
        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();
// ToggleSlider 滑动条设置当前 brightnessController 为监听者
        control.setOnChangedListener(this);
    }

   // 添加 
    public void addStateChangedCallback(BrightnessStateChangeCallback cb) {
        mChangeCallbacks.add(cb);
    }
    // 移除 
    public boolean removeStateChangedCallback(BrightnessStateChangeCallback cb) {
        return mChangeCallbacks.remove(cb);
    }

在BrightnessController 中实现 了ToggleSlide 的接口onChange(),当ToggleSlide的触发滑动改变时，所有已监听成员对应改变

 toggleSlider的接口实现
    public void onChanged(ToggleSlider view, boolean tracking, boolean automatic, int value) {
        setMode(automatic ? Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC
                : Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
        updateIcon(automatic);
        if (!automatic) {
            final int val = value + mMinimumBacklight;
            setBrightness(val);
            if (!tracking) {
                AsyncTask.execute(new Runnable() {
                        public void run() {
                            Settings.System.putIntForUser(mContext.getContentResolver(),
                                    Settings.System.SCREEN_BRIGHTNESS, val,
                                    UserHandle.USER_CURRENT);
                        }
                    });
            }
        }

        for (BrightnessStateChangeCallback cb : mChangeCallbacks) {
            cb.onBrightnessLevelChanged();
        }
    }

BrightnessController 类是为了处理改变事件的监听，及需要触发其他监听者回调，监听的添加移除等逻辑 (mvc 的 c)

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ToggleSlider 类 也是一个视图类，显示滑杆，滑块，并处理对应的滑动事件，略。