Hi all,
I’m trying to make a small program that detect the power button event.
The platform I’m working on is an x86 Atom board that runs Ubuntu Server 12.04, with Qt embedded v4.8 (I use embedded version because I need to run my applications in framebuffer).
I compiled the Qt framework using these command line arguments:
./configure -prefix /usr/local -no-largefile -no-accessibility -no-qt3support -no-xmlpatterns -platform qws/linux-x86-g++ -no-cups -dbus -embedded x86 -qt-gfx linuxfb -qt-mouse-tslib -system-zlib -system-libtiff -system-libpng -system-libjpeg -no-pch -no-openssl -no-declarative -no-declarative-debug -no-webkit -no-javascript-jit -no-script -no-scripttools -nomake demos -nomake examples
I’ve coded a small program that listens for ACPI events on /var/run/acpid.socket (this is the unix socket used by the acpid daemon, and everytime I push the power button the acpid daemon writes onto this socket).
I add my code below:
// TestQtAcpi.pro
#-------------------------------------------------
#
# Project created by QtCreator 2013-01-14T17:13:28
#
#-------------------------------------------------
QT += core gui network
SOURCES += main.cpp \
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui
TEMPLATE = app
// main.cpp
#include <QtGui/QApplication>
#ifdef Q_WS_QWS
#include <QWSServer>
#endif
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
#ifdef Q_WS_QWS
QWSServer::setCursorVisible( false );
w.showFullScreen();
#else
w.show();
#endif
return a.exec();
}
// mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtNetwork/QLocalSocket>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
int count;
QLocalSocket *socket;
private:
Ui::MainWindow *ui;
public slots:
void onSocketDataReady();
void onSocketError(QLocalSocket::LocalSocketError);
};
#endif // MAINWINDOW_H
// mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#ifdef _WIN32
#define SOCKET_NAME "\\\\.\\pipe\\foo"
#endif
#ifdef __linux__
#define SOCKET_NAME "/var/run/acpid.socket"
#endif
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
count = 0;
socket = new QLocalSocket(this);
connect(socket, SIGNAL(readyRead()), this, SLOT(onSocketDataReady()));
connect(socket, SIGNAL(error(QLocalSocket::LocalSocketError)), this, SLOT(onSocketError(QLocalSocket::LocalSocketError)));
socket->connectToServer(SOCKET_NAME, QIODevice::ReadOnly);
if (socket->waitForConnected(1000))
qDebug("Connected!");
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::onSocketDataReady()
{
QString data(socket->readAll());
count++;
ui->labelCount->setText(QString::number(count));
if(data.contains(QString("button/power")))
qDebug("PowerButton pressed detected!");
}
void MainWindow::onSocketError(QLocalSocket::LocalSocketError error)
{
qDebug() << "Socket Error: " << error;
}
Basically, the program opens a socket on /var/run/acpid.socket using QLocalSocket object, and every time that there are some bytes available on that socket the readyRead event is triggered and the slot onSocketDataReady should be called. Inside this slot, a counter is incremented and a label on the GUI is updated (just to show that the slot has being called).
I’ve tested this program on my windows machine (I wrote another program that uses QLocalServer to emulate the behaviour of the linux acpid daemon) and the application works as expected, every time there are data on the socket the slot is called and executed.
Running the application on the linux machine with Qt embedded leads to strange behaviour, the slot is not always called. I’m not saying that the slot is never called, sometimes it is called and sometimes not…
I’ll try to explain better what’s happening:
I run the program on the embedded board, then I start to press the power button to see if it detects correctly the events, at this point the situation is that the counter is not incremented at every button press, sometimes I need to press the button 3 or 4 times to see the counter increment (and thus the slot being called), sometimes it increments immediatly after the button press, but this behaviour is not predictable and I don’t understand which is the cause of this problem…
Any help/suggestions are really appreciated!
Samuele.
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