android button light 流程分析(三) — framework

最新推荐文章于 2025-02-08 14:35:29 发布

g_salamander

最新推荐文章于 2025-02-08 14:35:29 发布

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分类专栏：源码分析文章标签： button android keyboard 代码分析 jni resources

本文链接：https://blog.youkuaiyun.com/g_salamander/article/details/7947832

本文深入探讨Android framework层如何处理电源状态，尤其是针对button背光的控制。从config.xml中配置的背光参数开始，分析初始化过程，并详细阐述当输入事件发生时，PowerManagerService如何响应，通过userActivity()、setPowerState()和setLightBrightness()等函数调整LED和LCD背光的状态。同时，讲解了在setPowerState()中更新LED状态和在setLightBrightness()中调用JNI接口设置背光的过程。

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一、初始化信息

首先看看Android中的几种电源状态定义，这几个值定义了不同的led开闭状态以及lcd背光的不同亮度模式:

    // flags for setPowerState
    private static final int SCREEN_ON_BIT          = 0x00000001;
    private static final int SCREEN_BRIGHT_BIT      = 0x00000002;
    private static final int BUTTON_BRIGHT_BIT      = 0x00000004;
    private static final int KEYBOARD_BRIGHT_BIT    = 0x00000008;
    private static final int BATTERY_LOW_BIT        = 0x00000010;

    // values for setPowerState

    // SCREEN_OFF == everything off
    private static final int SCREEN_OFF         = 0x00000000;

    // SCREEN_DIM == screen on, screen backlight dim
    private static final int SCREEN_DIM         = SCREEN_ON_BIT;

    // SCREEN_BRIGHT == screen on, screen backlight bright
    private static final int SCREEN_BRIGHT      = SCREEN_ON_BIT | SCREEN_BRIGHT_BIT;

    // SCREEN_BUTTON_BRIGHT == screen on, screen and button backlights bright
    private static final int SCREEN_BUTTON_BRIGHT  = SCREEN_BRIGHT | BUTTON_BRIGHT_BIT;

    // SCREEN_BUTTON_BRIGHT == screen on, screen, button and keyboard backlights bright
    private static final int ALL_BRIGHT         = SCREEN_BUTTON_BRIGHT | KEYBOARD_BRIGHT_BIT;

    // used for noChangeLights in setPowerState()
    private static final int LIGHTS_MASK        = SCREEN_BRIGHT_BIT | BUTTON_BRIGHT_BIT | KEYBOARD_BRIGHT_BIT;

在frameworks/base/core/res/res/values/config.xml中配置自动背光的总开关mUseSoftwareAutoBrightness以及自动背光模式下的背光数值，如果没有lightsensor用于自动背光调整，则需要将mUseSoftwareAutoBrightness配置为false，配置项如下:

    <bool name="config_automatic_brightness_available">true</bool>

    <!-- Array of light sensor LUX values to define our levels for auto backlight brightness support.
         The N entries of this array define N + 1 zones as follows:

         Zone 0:        0 <= LUX < array[0]
         Zone 1:        array[0] <= LUX < array[1]
         ...
         Zone N:        array[N - 1] <= LUX < array[N]
         Zone N + 1:    array[N] <= LUX < infinity

         Must be overridden in platform specific overlays -->
    <integer-array name="config_autoBrightnessLevels">
        <item>3</item>
        <item>10</item>
        <item>40</item>
        <item>65</item>
        <item>145</item>
        <item>300</item>
        <item>550</item>
        <item>930</item>
        <item>1250</item>
    </integer-array>

    <!-- Array of output values for LCD backlight corresponding to the LUX values
         in the config_autoBrightnessLevels array.  This array should have size one greater
         than the size of the config_autoBrightnessLevels array.
         This must be overridden in platform specific overlays -->
    <integer-array name="config_autoBrightnessLcdBacklightValues">
        <item>101</item>
        <item>117</item>
        <item>142</item>
        <item>183</item>
        <item>195</item>
        <item>216</item>
        <item>234</item>
        <item>245</item>
        <item>250</item>
        <item>250</item>
    </integer-array>

    <!-- Array of output values for button backlight corresponding to the LUX values
         in the config_autoBrightnessLevels array.  This array should have size one greater
         than the size of the config_autoBrightnessLevels array.
         This must be overridden in platform specific overlays -->
    <integer-array name="config_autoBrightnessButtonBacklightValues">
        <item>255</item>
        <item>255</item>
        <item>255</item>
        <item>0</item>
        <item>0</item>
        <item>0</item>
        <item>0</item>
        <item>0</item>
        <item>0</item>
        <item>0</item>
    </integer-array>

    <!-- Array of output values for keyboard backlight corresponding to the LUX values
         in the config_autoBrightnessLevels array.  This array should have size one greater
         than the size of the config_autoBrightnessLevels array.
         This must be overridden in platform specific overlays -->
    <integer-array name="config_autoBrightnessKeyboardBacklightValues">
    </integer-array>

在初始化的时候会调用如下代码获取配置信息:

        // 获取系统默认配置
        Resources resources = mContext.getResources();
        // 屏幕动画是否开启
        mAnimateScreenLights = resources.getBoolean(
                com.android.internal.R.bool.config_animateScreenLights);

        mUnplugTurnsOnScreen = resources.getBoolean(
                com.android.internal.R.bool.config_unplugTurnsOnScreen);
        // 软件自动背光调整是否打开
        mUseSoftwareAutoBrightness = resources.getBoolean(
                com.android.internal.R.bool.config_automatic_brightness_available);
        // 读取自动背光参考值
        if (mUseSoftwareAutoBrightness) {
            mAutoBrightnessLevels = resources.getIntArray(
                    com.android.internal.R.array.config_autoBrightnessLevels);
            mLcdBacklightValues = resources.getIntArray(  // lcd背光值
                    com.android.internal.R.array.config_autoBrightnessLcdBacklightValues);
            mButtonBacklightValues = resources.getIntArray(  // button背光值
                    com.android.internal.R.array.config_autoBrightnessButtonBacklightValues);
            mKeyboardBacklightValues = resources.getIntArray(  // keyboard背光值
                    com.android.internal.R.array.config_autoBrightnessKeyboardBacklightValues);
            mLightSensorWarmupTime = resources.getInteger(
                    com.android.internal.R.integer.config_lightSensorWarmupTime);