Android按鍵燈流程分析

調(diào)用代碼為：

alps\frameworks\base\services\java\com\Android\server\LightsService.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：

alps\frameworks\base\services\jni\com_android_server_LightsService.cpp

接口關(guān)聯(lián)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(shù)在alps\frameworks\base\services\jni\onload.cpp里面注冊

本地c代碼在：

alps\mediatek\hardware\liblights\lights.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(diào)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(guān)按鍵燈

echo 1 > /sys/class/leds/button-backlight/brightness 開按鍵燈

echo 0 > /sys/class/leds/button-backlight/brightness 執(zhí)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(shè)備，并執(zhí)行write將0帶入執(zhí)行。