Android defines a user space C abstraction interface for LED hardware. The interface header is defined inhardware/libhardware/include/hardware/lights.h. In order to integrate LEDs with Android you need to build a shared library that implements this interface. The types of logical lights currently supported by Android include:

Backlight
Keyboard
Buttons
Battery
Notifications
Attention

Building a Lights Library

To implement a Lights driver, create a shared library that implements the interface defined in lights.h. You must name your shared library liblights.so so that it will get loaded from /system/libat runtime.

Interface

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lights.h File Reference

Data Structures

struct light_device_

tstruct light_state_t

The parameters that can be set for a given light. More...

00001 /*00002  * Copyright (C) 2008 The Android Open Source Project00003  *00004  * Licensed under the Apache License, Version 2.0 (the "License");00005  * you may not use this file except in compliance with the License.00006  * You may obtain a copy of the License at00007  *00008  *      http://www.apache.org/licenses/LICENSE-2.000009  *00010  * Unless required by applicable law or agreed to in writing, software00011  * distributed under the License is distributed on an "AS IS" BASIS,00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.00013  * See the License for the specific language governing permissions and00014  * limitations under the License.00015  */00016 00017 #ifndef ANDROID_LIGHTS_INTERFACE_H00018 #define ANDROID_LIGHTS_INTERFACE_H00019 00020 #include 00021 #include 00022 #include 00023 00024 #include 00025 00026 __BEGIN_DECLS00027 00028 /**00029  * The id of this module00030  */00031 #define LIGHTS_HARDWARE_MODULE_ID "lights"00032 00033 /*00034  * These light IDs correspond to logical lights, not physical.00035  * So for example, if your INDICATOR light is in line with your00036  * BUTTONS, it might make sense to also light the INDICATOR00037  * light to a reasonable color when the BUTTONS are lit.00038  */00039 #define LIGHT_ID_BACKLIGHT          "backlight"00040 #define LIGHT_ID_KEYBOARD           "keyboard"00041 #define LIGHT_ID_BUTTONS            "buttons"00042 #define LIGHT_ID_BATTERY            "battery"00043 #define LIGHT_ID_NOTIFICATIONS      "notifications"00044 #define LIGHT_ID_ATTENTION          "attention"00045 00046 /*00047  * These lights aren't currently supported by the higher00048  * layers, but could be someday, so we have the constants00049  * here now.00050  */00051 #define LIGHT_ID_BLUETOOTH          "bluetooth"00052 #define LIGHT_ID_WIFI               "wifi"00053 00054 /* ************************************************************************00055  * Flash modes for the flashMode field of light_state_t.00056  */00057 00058 #define LIGHT_FLASH_NONE            000059 00060 /**00061  * To flash the light at a given rate, set flashMode to LIGHT_FLASH_TIMED,00062  * and then flashOnMS should be set to the number of milliseconds to turn00063  * the light on, followed by the number of milliseconds to turn the light00064  * off.00065  */00066 #define LIGHT_FLASH_TIMED           100067 00068 /**00069  * To flash the light using hardware assist, set flashMode to00070  * the hardware mode.00071  */00072 #define LIGHT_FLASH_HARDWARE        200073 00074 /**00075  * Light brightness is managed by a user setting.00076  */00077 #define BRIGHTNESS_MODE_USER        000078 00079 /**00080  * Light brightness is managed by a light sensor.00081  */00082 #define BRIGHTNESS_MODE_SENSOR      100083 00084 /**00085  * The parameters that can be set for a given light.00086  *00087  * Not all lights must support all parameters.  If you00088  * can do something backward-compatible, you should.00089  */00090 struct light_state_t {00091     /**00092      * The color of the LED in ARGB.00093      *00094      * Do your best here.00095      *   - If your light can only do red or green, if they ask for blue,00096      *     you should do green.00097      *   - If you can only do a brightness ramp, then use this formula:00098      *      unsigned char brightness = ((77*((color>>16)&0x00ff))00099      *              + (150*((color>>8)&0x00ff)) + (29*(color&0x00ff))) >> 8;00100      *   - If you can only do on or off, 0 is off, anything else is on.00101      *00102      * The high byte should be ignored.  Callers will set it to 0xff (which00103      * would correspond to 255 alpha).00104      */00105     unsigned int color;00106 00107     /**00108      * See the LIGHT_FLASH_* constants00109      */00110     int flashMode;00111     int flashOnMS;00112     int flashOffMS;00113 00114     /**00115      * Policy used by the framework to manage the light's brightness.00116      * Currently the values are BRIGHTNESS_MODE_USER and BRIGHTNESS_MODE_SENSOR.00117      */00118     int brightnessMode;00119 };00120 00121 struct light_device_t {00122     struct hw_device_t common;00123 00124     /**00125      * Set the provided lights to the provided values.00126      *00127      * Returns: 0 on succes, error code on failure.00128      */00129     int (*set_light)(struct light_device_t* dev,00130             struct light_state_t const* state);00131 };00132 00133 00134 __END_DECLS00135 00136 #endif  // ANDROID_LIGHTS_INTERFACE_H00137

原文：http://source.android.com/porting/lights.html

Android(安卓)Lights

Building a Lights Library

Interface

lights.h File Reference

Data Structures

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