一. Android系统源码中的参数配置
MTK6771平台自己重写了背光曲线的参数,路径在s0_vnd/vendor/mediatek/proprietary/packages/overlay/vendor/FrameworkResOverlayExt/brightness_adaptive_support/res/values/config.xml
不过MTK的其他平台可能不是在这个路径
来看 config.xml 这个文件中需要配置的两个参数:
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config_autoBrightnessLevels // 环境光对应的值
config_autoBrightnessLcdBacklightValues // 显示屏对应的亮度值(范围 0-255)
这两个参数在文件 t0_sys\frameworks\base\services\core\java\com\android\server\display\BrightnessMappingStrategy.java
中被加载
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@Nullable
private static BrightnessMappingStrategy create(Resources resources,
DisplayDeviceConfig displayDeviceConfig, boolean isForIdleMode,
DisplayWhiteBalanceController displayWhiteBalanceController) {
// Display independent, mode dependent values
float[] brightnessLevelsNits;
float[] luxLevels;
if (isForIdleMode) {
brightnessLevelsNits = getFloatArray(resources.obtainTypedArray(
com.android.internal.R.array.config_autoBrightnessDisplayValuesNitsIdle));
luxLevels = getLuxLevels(resources.getIntArray(
com.android.internal.R.array.config_autoBrightnessLevelsIdle));
} else {
brightnessLevelsNits = getFloatArray(resources.obtainTypedArray(
com.android.internal.R.array.config_autoBrightnessDisplayValuesNits));
// 从资源文件中获取环境光参数
luxLevels = getLuxLevels(resources.getIntArray(
com.android.internal.R.array.config_autoBrightnessLevels));
}
// Display independent, mode independent values
int[] brightnessLevelsBacklight = resources.getIntArray(com.android.internal.R.array.config_autoBrightnessLcdBacklightValues);
float autoBrightnessAdjustmentMaxGamma = resources.getFraction(
com.android.internal.R.fraction.config_autoBrightnessAdjustmentMaxGamma,
1, 1);
long shortTermModelTimeout = resources.getInteger(
com.android.internal.R.integer.config_autoBrightnessShortTermModelTimeout);
// Display dependent values - used for physical mapping strategy nits -> brightness
final float[] nitsRange = displayDeviceConfig.getNits();
final float[] brightnessRange = displayDeviceConfig.getBrightness();
// 判断是否是有效的映射
if (isValidMapping(nitsRange, brightnessRange)
&& isValidMapping(luxLevels, brightnessLevelsNits)) {
BrightnessConfiguration.Builder builder = new BrightnessConfiguration.Builder(
luxLevels, brightnessLevelsNits);
builder.setShortTermModelTimeoutMillis(shortTermModelTimeout);
builder.setShortTermModelLowerLuxMultiplier(SHORT_TERM_MODEL_THRESHOLD_RATIO);
builder.setShortTermModelUpperLuxMultiplier(SHORT_TERM_MODEL_THRESHOLD_RATIO);
// 物理映射策略 映射Lux值和Nits值,而非Lux值和直接显示的背光值,物理映射
return new PhysicalMappingStrategy(builder.build(), nitsRange, brightnessRange,
autoBrightnessAdjustmentMaxGamma, isForIdleMode, displayWhiteBalanceController);
} else if (isValidMapping(luxLevels, brightnessLevelsBacklight) && !isForIdleMode) {
// 简单映射,直接映射Lux值和Backlight值
return new SimpleMappingStrategy(luxLevels, brightnessLevelsBacklight,
autoBrightnessAdjustmentMaxGamma, shortTermModelTimeout);
} else {
return null;
}
}
通过打印得知最终是使用简单映射的方法形成背光曲线,即通过SimpleMappingStrategy方法来将lux值跟Brightness值直接映射
接下来咋们直接配置config.xml文件中的两个参数
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<integer-array name="config_autoBrightnessLevels">
<item>128</item>
<item>256</item>
<item>512</item>
<item>1024</item>
<item>2048</item>
<item>4096</item>
<item>6144</item>
<item>8192</item>
<item>10240</item>
<item>12288</item>
<item>14336</item>
<item>18432</item>
<item>22528</item>
<item>30720</item>
<item>47104</item>
<item>79872</item>
<item>145408</item>
</integer-array>
<integer-array name="config_autoBrightnessLcdBacklightValues">
<item>2</item>
<item>15</item>
<item>22</item>
<item>35</item>
<item>52</item>
<item>75</item>
<item>110</item>
<item>137</item>
<item>160</item>
<item>182</item>
<item>200</item>
<item>221</item>
<item>255</item>
<item>255</item>
<item>255</item>
<item>255</item>
<item>255</item>
<item>255</item>
</integer-array>
在上述参数配置中,当环境光的值是128时,那么显示屏的亮度值将调节到15
config_autoBrightnessLevels 有17个参数,config_autoBrightnessLcdBacklightValues有18个参数
获取config_autoBrightnessLevels 的数组在初始化的时候会将第一个参数设置为0,资源文件中配置17个参数即可
config_autoBrightnessLcdBacklightValues 中的数据是显示屏的亮度值,范围为0-255,也就是说按亮度百分比来算的话
1%的亮度他的亮度值是2.55
二. adb命令查看display相关信息
进入adb shell 后,使用 dumpsys display 命令查看display的相关信息。如下图所示输入dumpsys display 命令后可以配置好的背光曲线
三. 一些bug
- 当环境光大于20000lux时,显示屏亮度被调到1%了...
查看 t0_sys\frameworks\base\services\core\java\com\android\server\display\AutomaticBrightnessController.java
这个文件中光传感器监听到的数据
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private final SensorEventListener mLightSensorListener = new SensorEventListener() {
@Override
public void onSensorChanged(SensorEvent event) {
if (mLightSensorEnabled) {
final long time = mClock.uptimeMillis();
final float lux = event.values[0];
Slog.i("test","testlux:" + lux);
handleLightSensorEvent(time, lux);
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// Not used.
}
};
将光传感器监听的数据打印后发现,环境光亮度是20000lux的时候,理论上mLightSensorListener 监听中打印lux的值也应该是20000,但实际上打印的值是0,这就好理解了,环境光大于20000lux的但是光感上报的值是0lux,是0的话那么显示屏亮度就被调到1%了...
查看代码修改记录,发现光感驱动的环境光等级和值被人改了
默认是:
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.als_level = {0, 50, 200, 500, 2500, 7721, 7767, 12621, 23062, 28430, 33274, 47116, 57694, 57694, 65535},
.als_value = {0, 2, 200, 450, 800, 1100, 1600, 6000, 8200, 8800, 12000, 13000, 16000, 20000, 20000},
被改成:
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.als_level = {0, 23, 46, 93, 186, 214, 290, 450, 621, 845, 1136, 1545, 2364, 4655, 6982}, //0-4096
.als_value = {0, 2, 20, 80, 200, 320, 800, 1100, 1600, 6000, 8200, 8800, 12000, 13000, 16000},
将被修改的内容还原后这个Bug就没了...