Android按鍵燈流程分析
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調用代碼為：
本文引用地址：http://cqxgywz.com/article/201610/306010.htmalpsframeworksbaseservicesjavacomAndroidserverLightsService.java
使用方法：
private LightsService.Light mButtonLight;
mButtonLight = mLightsService.getLight(LightsService.LIGHT_ID_BUTTONS);
mButtonLight.setBrightness(screenBrightness);
mButtonLight.turnOff();
本地代碼在：
alpsframeworksbaseservicesjnicom_android_server_LightsService.cpp
接口關聯使用：
static JNINativeMethod method_table[] = {
{ init_native, ()I, (void*)init_native },
{ finalize_native, (I)V, (void*)finalize_native },
{ setLight_native, (IIIIIII)V, (void*)setLight_native },
};
int register_android_server_LightsService(JNIEnv *env)
{
return jniRegisterNativeMethods(env, com/android/server/LightsService,
method_table, NELEM(method_table));
}
register_android_server_LightsService函數在alpsframeworksbaseservicesjnionload.cpp里面注冊
本地c代碼在：
alpsmediatekhardwareliblightslights.c里面open_lights里面
static int
set_light_buttons(struct light_device_t* dev,
struct light_state_t const* state)
{
int err = 0;
int on = is_lit(state);
pthread_mutex_lock(g_lock);
g_buttons = on;
err = write_int(BUTTON_FILE, on?255:0);
pthread_mutex_unlock(g_lock);
return err;
}
com_android_server_LightsService.cp里面使用 devices->lights[light]->set_light(devices->lights[light], state);來調用真正的代碼
如果有root機子，可以如下測試：
echo 0 > /sys/class/leds/button-backlight/brightness 關按鍵燈
echo 1 > /sys/class/leds/button-backlight/brightness 開按鍵燈
echo 0 > /sys/class/leds/button-backlight/brightness 執行的意思為：輸出0，作為/sys/class/leds/button-backlight/brightness的輸入傳入。
如此便會打開brightness設備，并執行write將0帶入執行。
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