I've got some code that starts mencoder in a QProcess, converts a video while displaying a progress bar, then exits. The problem is, mencoder always exits before it's actually finished. The loop runs through a few times, and then closes. If I comment out the line that updates the progress bar (progress.setValue()), mencoder runs to completion and exits happily.
Been at this for a day, and can't figure it out! Also, I should mention I'm on a Mac.
Any ideas?
Thanks
Marlon
void MainWindow::convertVideo()
{
QString input_filename = "/var/input.avi";
QString output_filename = "/var/output.264";
QStringList arguments;
arguments << input_filename << "-nosound" << "-of" << "rawvideo" << "-ofps" << "30" << "-vf" << "harddup" << "-ovc" << "x264" << "-x264encopts" << "bframes=0" << "-o" << output_filename;
QProcess* myProcess = new QProcess(this);
myProcess->setReadChannel(QProcess::StandardOutput);
myProcess->start("/opt/local/bin/mencoder", arguments);
QString output_string;
QStringList output_pieces;
QProgressDialog progress("Converting video...", "Abort", 0, 100, this);
progress.setWindowModality(Qt::WindowModal);
progress.setValue(0);
progress.show();
while(myProcess->state() != QProcess::NotRunning)
{
output_string = myProcess->readAllStandardOutput();
output_pieces = output_string.split(" ");
QStringList width_string_list = output_pieces.filter("%)");
if(width_string_list.length() > 0)
{
width_string_list = width_string_list[width_string_list.length() - 1].split("(");
if(width_string_list.length() > 1)
{
width_string_list = width_string_list[1].split("%");
}
else
{
width_string_list = width_string_list[0].split("%");
}
progress.setValue(width_string_list[0].toInt());
qDebug() << width_string_list[0].toInt();
}
myProcess->waitForReadyRead();
}
return;
}
I think the QProcess timeouts before it finishes its job. Adding a myProcess->waitForFinished(-1) might help. Then your process wont timeout.
Related
The following code works - "echo" program is called for "abc" and "def",
the results are collected and printed.
If timer delay is set to 0, it stops working.
"echo" is called, even the readLine (if called) would return the right content,
but "finished" slot is never called. process.state() shows that the process is still running.
Why?
QFuture<QString> tfuture;
QFutureWatcher<QString> twatcher;
QString ftest(QString a){
QProcess process;
QEventLoop loop;
QObject::connect(&process, &QProcess::finished, [&](int exit_code) {
qDebug() << "OK " << a << " " << exit_code;
loop.exit(0);
});
QTimer::singleShot(1, [&] {
qDebug() << "STARTING " << a;
process.start("echo", {{"ECHO ", a}});
});
loop.exec();
return process.readLine();
};
void tfinished() {
QList<QString> result = twatcher.future().results();
qDebug() << "finished " << result;
}
...
QStringList params = {{"abc", "def"}};
tfuture = QtConcurrent::mapped(params, ftest);
connect(&twatcher, &QFutureWatcher<QString>::finished, this, &tfinished);
twatcher.setFuture(tfuture);
I'm not very good at character devices, so I need your help. A have a char device(let's call it /dev/my_light) which is a light sensor. I have to read the data from this file and transform it to the brightness value and then pass it to the brightness manager that changes the brightness of my screen. The problem is that when I read the value for some period of time I get old values from the file.I assume there is a buffer(again not sure how character devices exactly work). Whereas when I use cat /dev/my_light I see new data! Is it possible to get rid off the buffer and read new values that were written to the file just right now. Here is my code in Qt:
void MySensor::updateMySensor()
{
Packet packet;
packet.startByte = 0;
packet.mantissa = 0;
packet.exp = 0;
d->device = ::open(d->path.toStdString().c_str(), O_RDONLY);
if (d->device == -1)
{
qDebug() << Q_FUNC_INFO << "can't open the sensor";
return;
}
ssize_t size = ::read(d->device, &packet, sizeof(packet));
close(d->device);
if (size == -1)
{
qDebug() << errno;
return;
}
packet.exp &= 0x0F;
float illumination = pow(2, packet.exp) * packet.mantissa * 0.045;
if(d->singleShot) emit lightSensorIsRunning(true);
emit illuminationRead(illumination);
}
The mySensor function is called every second. I tried to call it each 200 msec but it didn't help. The value of illumination stays old for about 7 seconds(!) whereas the value that I get from cat is new just immediately.
Thank you in advance!
I can't test with your specific device, however, I'm using the keyboard as a read only device.
The program attempts to connect to keyboard and read all keys pressed inside and outside the window. It's a broad solution you'll have to adapt to meet your demands.
Note that I'm opening the file with O_RDONLY | O_NONBLOCK which means open in read only mode and no wait for the event be triggered(some notifier needed to know when data is ready!) respectively.
You'll need super user privilege to run this example!
#include <QtCore>
#include <fcntl.h>
#include <linux/input.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
const char *device_name = "/dev/input/by-path/platform-i8042-serio-0-event-kbd";
int descriptor = open(device_name, O_RDONLY | O_NONBLOCK);
if (descriptor < 0)
{
qDebug() << "Error" << strerror(errno);
return a.exec();
}
QFile device;
if (!device.open(descriptor, QFile::ReadOnly))
{
qDebug() << "Error" << qPrintable(device.errorString());
return a.exec();
}
QSocketNotifier notifier(device.handle(), QSocketNotifier::Read);
QObject::connect(¬ifier, &QSocketNotifier::activated, ¬ifier, [&](int socket){
Q_UNUSED(socket)
struct input_event ev;
QByteArray data = device.readAll();
qDebug() << "Event caught:"
<< "\n\nDATA SIZE" << data.size()
<< "\nSTRUCT COUNT" << data.size() / int(sizeof(input_event))
<< "\nSTRUCT SIZE" << sizeof(input_event);
qDebug() << ""; //New line
while (data.size() >= int(sizeof(input_event)))
{
memcpy(&ev, data.data(), sizeof(input_event));
data.remove(0, int(sizeof(input_event)));
qDebug() << "TYPE" << ev.type << "CODE" << ev.code << "VALUE" << ev.value << "TIME" << ev.time.tv_sec;
}
qDebug() << ""; //New line
});
return a.exec();
}
I have multiples DNS record (MX, CNAME , TXT) and I would like to read the TXT record content.
The lookup() function never emit finished(), I am using this code to test:
QDnsLookup m_dns = new QDnsLookup(this);
connect(m_dns, SIGNAL(finished()), this, SLOT(onHandle()));
m_dns->setType(QDnsLookup::TXT);
m_dns->setName("uol.com.br");
m_dns->lookup();
void Update::onHandle()
{
if (m_dns->error() != QDnsLookup::NoError)
qDebug() << m_dns->error() << m_dns->errorString();
foreach (const QDnsServiceRecord &record, m_dns->serviceRecords())
qDebug() << "Name: " << record.name();
emit handled();
}
If I use a online service to read the record, it works!
The onHandle slot should be looking at m_dns->textRecords(), not m_dns->serviceRecords().
The correct code:
foreach (const QDnsTextRecord &record , m_dns->textRecords()) {
qDebug() << "Values: " << record.values();
qDebug() << "Name: " << record.name();
}
I have a sever client application and in the beginning client loads data from server. I have a dialog showing status of getting data from server (has progress bar). But when I call the function the dialog appears with no contents in it with white background and suddenly changes to completed status.
void SystemScreen::loadServerData()
{
qDebug() << Q_FUNC_INFO << "Invoked";
if (NULL != mpDataManagerDlg)
{
qDebug() << Q_FUNC_INFO << "show progres screen";
mpDataManagerDlg->showScreen();
}
loadData();
qDebug() << Q_FUNC_INFO << "Exits";
}
void SystemScreen::loadData()
{
qDebug() << Q_FUNC_INFO << "Invoked";
if (NULL != mpDataManager)
{
mpDataManager->loadDataFromServer();
}
qDebug() << Q_FUNC_INFO << "Exits";
}
I feel that dialog is displayed only after loadData() function is completed. Is there any alternative to do this?
I used a timer to start
QTimer::singleShot(100, this, SLOT(loadData()));
But then I have some trouble in getting data. ie data is empty if I read suddenly.
EDIT:
void DataManagerDialog::setDefault()
{
qDebug() << Q_FUNC_INFO << "Invoked";
setProgressBar(0);
setProgressBarColor(false);
ui->deptFailButton->hide();
ui->deptOkButton->hide();
ui->deptLabel->setStyleSheet("color:gray");
ui->subGroupFailButton->hide();
ui->subGroupOkButton->hide();
ui->subGroupLabel->setStyleSheet("color:gray");
ui->itemFailButton->hide();
ui->itemOkButton->hide();
ui->itemLabel->setStyleSheet("color:gray");
ui->salesBtnFailButton->hide();
ui->salesBtnOkButton->hide();
ui->salesBtnLabel->setStyleSheet("color:gray");
qDebug() << Q_FUNC_INFO << "Exits";
}
void DataManagerDialog::alignCenter()
{
qDebug() << Q_FUNC_INFO << "Invoked";
QWidget *par = parentWidget();
if (par)
{
int x = width()/2;
int y = height()/2;
QPoint mid(mapToGlobal(QPoint(x, y)));
int px = par->width()/2;
int py = par->height()/2;
QPoint parMid(mapToGlobal(QPoint(px, py)));
move(parMid.x()-mid.x(), parMid.y()-mid.y());
}
qDebug() << Q_FUNC_INFO << "Exits";
}
void DataManagerDialog::showScreen()
{
setDefault();
alignCenter();
show();
}
You probably do not enter the event loop.
Try to call QCoreApplication::processEvents() from time to time in mpDataManager->loadDataFromServer() to update the GUI.
From the processEvents documentation :
You can call this function occasionally when your program is busy performing a long operation (e.g. copying a file).
Edit added after getting feedback from the comments
A better approach would be to send signals in your loadDataFromServer() method with the status information and have a slot listen to the signal and update the GUI.
Here a prototype illustrating the idea :
void mpDataManagerDlg::loadDataFromServer() {
while(true) {
// do some work
int progress = // some value
emit updateDialogSignal(progress);
}
}
// in your dialog class
public slots:
void DataManagerDialog::updateDialog(int progress) {
// update gui
}
More about signals and slots can be found here.
I am writing a class to parse Itunes Libray File using QXmlQuery and QT-XSLT.
Here's my sample code:
ItunesLibParser::ItunesLibParser()
{
pathToLib = QString("/Users/rakesh/temp/itunes_xslt/itunes_music_library.xml");
}
void ItunesLibParser::createXSLFile(QFile &inFile)
{
if (inFile.exists()) {
inFile.remove();
}
inFile.open(QIODevice::WriteOnly);
QTextStream out(&inFile);
out << QString("<?xml version=\"1.0\" encoding=\"ISO-8859-1\"?>");
out << QString("<xsl:stylesheet version=\"2.0\" xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\">");
out << QString("<xsl:output method=\"text\" />");
out << QString("<xsl:template name=\"playlistNames\">");
out << QString("<xsl:value-of select=\"child::integer[preceding-sibling::key[1]='Playlist ID']\"/>");
out << QString("<xsl:text>
</xsl:text>");
out << QString("<xsl:value-of select=\"child::string[preceding-sibling::key[1]='Name']\"/>");
out << QString("<xsl:text>
</xsl:text>");
out << QString("</xsl:template>");
out << QString("<xsl:template match=\"/\">");
out << QString("<xsl:for-each select=\"plist/dict/array/dict\">");
out << QString("<xsl:call-template name=\"playlistNames\"/>");
out << QString("</xsl:for-each>");
out << QString("</xsl:template>");
out << QString("</xsl:stylesheet>");
inFile.close();
return;
}
void ItunesLibParser::dumpPlayList()
{
QXmlQuery query(QXmlQuery::XSLT20);
query.setFocus(QUrl(pathToLib));
QFile xslFile("plist.xsl");
createXSLFile(xslFile);
query.setQuery(QUrl("plist.xsl"));
QStringList* outDump = new QStringList();
query.evaluateTo(outDump);
if(outDump != NULL) {
QStringList::iterator iter = (*outDump).begin();
for (; iter != (*outDump).end();
++iter)
//code flow doesn't come here. It means being() == end()
std::cout << (*iter).toLocal8Bit().constData() << std::endl;
}
return;
}
OutDump here doesn't contain data. While in Shell (xmlpatterns-4.7 mystlye.xsl itunes_music_library.xml ), If I run my Query I get proper output.
Is there anything, wrong I am doing while calling it programatically? I checked out plist.xsl is created properly, but my doubt is whether "/Users/rakesh/temp/itunes_xslt/itunes_music_library.xml" this is getting loaded or not? Or there might be another reasons, I am confused. Is there any experts to throw some light onto problem, I will be glad.
Intead from reading from the file, I read the file into buffer and converted that int string as passed to setquery. That solved the problem.
Here's sample code for those who could face similar problem in future.
void ITunesMlibParser::parsePlayListItemXml(int plistId)
{
QXmlQuery xQuery(QXmlQuery::XSLT20);
QFile inFile("/Users/rakesh/temp/itunes_xslt/itunes_music_library.xml");
if (!inFile.open(QIODevice::ReadOnly)) {
return;
}
QByteArray bArray;
while (!inFile.atEnd()) {
bArray += inFile.readLine();
}
QBuffer xOriginalContent(&bArray);
xOriginalContent.open(QBuffer::ReadWrite);
xOriginalContent.reset();
if (xQuery.setFocus(&xOriginalContent))
std::cout << "File Loaded" << std::endl;
//..
//..
}
Thanks
Rakesh