Lights In this document - Android Platform Developer's Guide

Lights In this document
Building a Lights Library
Interface
Android defines a user space C abstraction interface for LED hardware. The interface header is defined in hardware/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/lib at runtime.
Interface
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lights.h
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00001 /*
00002 * Copyright (C) 2008 The Android Open Source Project
00003 *
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 at
00007 *
00008 * http://www.apache.org/licenses/LICENSE-2.0
00009 *
00010 * Unless required by applicable law or agreed to in writing, software
00011 * 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 and
00014 * limitations under the License.
00015 */
00016
00017 #ifndef ANDROID_LIGHTS_INTERFACE_H
00018 #define ANDROID_LIGHTS_INTERFACE_H
00019
00020 #include
00021 #include
00022 #include
00023
00024 #include
00025
00026 __BEGIN_DECLS
00027
00028 /**
00029 * The id of this module
00030 */
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 your
00036 * BUTTONS, it might make sense to also light the INDICATOR
00037 * 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 higher
00048 * layers, but could be someday, so we have the constants
00049 * 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 0
00059
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 turn
00063 * the light on, followed by the number of milliseconds to turn the light
00064 * off.
00065 */
00066 #define LIGHT_FLASH_TIMED 1
00067
00068
00069 /**
00070 * The parameters that can be set for a given light.
00071 *
00072 * Not all lights must support all parameters. If you
00073 * can do something backward-compatible, you should.
00074 */
00075 struct light_state_t {
00076 /**
00077 * The color of the LED in ARGB.
00078 *
00079 * Do your best here.
00080 * - If your light can only do red or green, if they ask for blue,
00081 * you should do green.
00082 * - If you can only do a brightness ramp, then use this formula:
00083 * unsigned char brightness = ((77*((color>>16)&0x00ff))
00084 * + (150*((color>>8)&0x00ff)) + (29*(color&0x00ff))) >> 8;
00085 * - If you can only do on or off, 0 is off, anything else is on.
00086 *
00087 * The high byte should be ignored. Callers will set it to 0xff (which
00088 * would correspond to 255 alpha).
00089 */
00090 unsigned int color;
00091
00092 /**
00093 * See the LIGHT_FLASH_* constants
00094 */
00095 int flashMode;
00096 int flashOnMS;
00097 int flashOffMS;
00098 };
00099
00100 struct light_device_t {
00101 struct hw_device_t common;
00102
00103 /**
00104 * Set the provided lights to the provided values.
00105 *
00106 * Returns: 0 on succes, error code on failure.
00107 */
00108 int (*set_light)(struct light_device_t* dev,
00109 struct light_state_t const* state);
00110 };
00111
00112
00113 __END_DECLS
00114
00115 #endif // ANDROID_LIGHTS_INTERFACE_H
00116
light_state_t Struct Reference
The parameters that can be set for a given light. More...
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Data Fields
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unsigned int
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color
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The color of the LED in ARGB.
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int
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flashMode
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See the LIGHT_FLASH_* constants.
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int
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flashOffMS
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int
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flashOnMS
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Detailed Description
The parameters that can be set for a given light.
Not all lights must support all parameters. If you can do something backward-compatible, you should.
Definition at line 75 of file lights.h.
Field Documentation
unsigned int light_state_t::color
|
The color of the LED in ARGB.
Do your best here.
If your light can only do red or green, if they ask for blue, you should do green.
If you can only do a brightness ramp, then use this formula: unsigned char brightness = ((77*((color>>16)&0x00ff)) + (150*((color>>8)&0x00ff)) + (29*(color&0x00ff))) >> 8;
If you can only do on or off, 0 is off, anything else is on.
The high byte should be ignored. Callers will set it to 0xff (which would correspond to 255 alpha).
Definition at line 90 of file lights.h.
int light_state_t::flashMode
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See the LIGHT_FLASH_* constants.
Definition at line 95 of file lights.h.
int light_state_t::flashOffMS
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Definition at line 97 of file lights.h.
int light_state_t::flashOnMS
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Definition at line 96 of file lights.h.
Audio In this document
Building an Audio Library
Interface
AudioHardwareInterface serves as the glue between proprietary audio drivers and the Android AudioFlinger service, the core audio service that handles all audio-related requests from applications.
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