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LED.java
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/* -*- mode: java; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
Copyright (c) The Processing Foundation 2015
Hardware I/O library developed by Gottfried Haider as part of GSoC 2015
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
*/
package processing.io;
import processing.io.NativeInterface;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
/**
* Opens a LED device.<br/>
* <br/>
* This class can control your computer's build-in LEDs, such as the ones
* commonly used to indicate the power status and disk activity.</br>
* <br/>
* Your operating system might not be set up to allow regular users to do this
* kind of modification. If this is the case you should install a so-called
* <i>udev rule</i> that relaxes the permissions for the files in
* /sys/class/leds. You can also try running Processing as root user using
* "sudo", but this is generally not recommended.
*
* @webref LED
* @webBrief Opens a LED device
*/
public class LED {
protected String dev;
protected int maxBrightness;
protected int prevBrightness;
protected String prevTrigger;
/**
* Opens a LED device
* @param dev device name
* @see list
* @webref LED
* @webBrief Opens a LED device
*/
public LED(String dev) {
NativeInterface.loadLibrary();
this.dev = dev;
if (NativeInterface.isSimulated()) {
return;
}
// read maximum brightness
try {
Path path = Paths.get("/sys/class/leds/" + dev + "/max_brightness");
String tmp = new String(Files.readAllBytes(path));
maxBrightness = Integer.parseInt(tmp.trim());
} catch (Exception e) {
System.err.println(e.getMessage());
throw new RuntimeException("Unable to read maximum brightness");
}
// read current trigger setting to be able to restore it later
try {
Path path = Paths.get("/sys/class/leds/" + dev + "/trigger");
String tmp = new String(Files.readAllBytes(path));
int start = tmp.indexOf('[');
int end = tmp.indexOf(']', start);
if (start != -1 && end != -1) {
prevTrigger = tmp.substring(start+1, end);
}
} catch (Exception e) {
System.err.println(e.getMessage());
throw new RuntimeException("Unable to read trigger setting");
}
// read current brightness to be able to restore it later
try {
Path path = Paths.get("/sys/class/leds/" + dev + "/brightness");
String tmp = new String(Files.readAllBytes(path));
prevBrightness = Integer.parseInt(tmp.trim());
} catch (Exception e) {
System.err.println(e.getMessage());
throw new RuntimeException("Unable to read current brightness");
}
// disable trigger
String fn = "/sys/class/leds/" + dev + "/trigger";
int ret = NativeInterface.writeFile(fn, "none");
if (ret < 0) {
if (ret == -13) { // EACCES
System.err.println("You might need to install a custom udev rule to allow regular users to modify /sys/class/leds/*.");
}
throw new RuntimeException(NativeInterface.getError(ret));
}
}
/**
* Sets the brightness
* @param bright 0.0 (off) to 1.0 (maximum)
* @webref LED
* @webBrief Sets the brightness
*/
public void brightness(float bright) {
if (bright < 0.0 || 1.0 < bright) {
System.err.println("Brightness must be between 0.0 and 1.0.");
throw new IllegalArgumentException("Illegal argument");
}
if (NativeInterface.isSimulated()) {
return;
}
String fn = "/sys/class/leds/" + dev + "/brightness";
int ret = NativeInterface.writeFile(fn, Integer.toString((int)(bright * maxBrightness)));
if (ret < 0) {
throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
}
}
/**
* Restores the previous state<br/>
* <br/>
* Without calling this function the LED will remain in the current state even
* after the sketch has been closed.
*
* @webref LED
* @webBrief Restores the previous state
*/
public void close() {
if (NativeInterface.isSimulated()) {
return;
}
// restore previous settings
String fn = "/sys/class/leds/" + dev + "/brightness";
int ret = NativeInterface.writeFile(fn, Integer.toString(prevBrightness));
if (ret < 0) {
throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
}
fn = "/sys/class/leds/" + dev + "/trigger";
ret = NativeInterface.writeFile(fn, prevTrigger);
if (ret < 0) {
throw new RuntimeException(fn + ": " + NativeInterface.getError(ret));
}
}
/**
* Lists all available LED devices
* @return String array
* @webref LED
* @webBrief Lists all available LED devices
*/
public static String[] list() {
if (NativeInterface.isSimulated()) {
// as on the Raspberry Pi
return new String[]{ "led0", "led1" };
}
ArrayList<String> devs = new ArrayList<>();
File dir = new File("/sys/class/leds");
File[] files = dir.listFiles();
if (files != null) {
for (File file : files) {
devs.add(file.getName());
}
}
// listFiles() does not guarantee ordering
String[] tmp = devs.toArray(new String[devs.size()]);
Arrays.sort(tmp);
return tmp;
}
}