General and Desktop

Hi, The library is one thing but do you have the development version of these dependencies in the sysroot ?

@wrosecrans said in QImage and OpenCV Mat problem: Most in-memory image formats for other API's are densely packed (at least by default). Then you should never decode a video stream with ffmpeg... Images in video streams are normally 32 byte aligned nowadays to perfectly match to cpu vector instructions and caches. The only thing I miss in QImage is to be able to specify this alignment in the ctor like e.g. av_image_alloc() allows.

@illud Do you think after 6 years, he's still looking for a solution? ;-) The topic is marked "solved" anyway :-)

@SaadAli said in Cant build QMYSQL driver on Ubuntu 22.04.2 LTS: The only thing that happened after installing it was I got the file libqsqlmysql.so on my machine. Yep that's fine, it must be supplied in libqt5sql5-mysql package and that is what is needed.

@AkashPatel28 Then please mark this topic as solved, thx.

@Damian7546 said in Reciving data from barcode scanner: receivedData.append(scannedData); if(receivedData.contains("\r\n")) parseRecivedData(); Why do you read it line by line just to append it to a QByteArray and split it again afterwards?

Hi and welcome to devnet, You can find the module sources here.

Not QTableView You should use findChild<QTableView*>("qt_calendar_calendarview")->viewport()->installEventFilter(this);

@DenizCaglar said in QWidget empty despite having children: I've seen some parts of the Qt documentation mention that particular functions take ownership of their pointer arguments This has nothing to do with my comment. I was refering to the parent-child relationship of QObjects

@Daemonitas Well, nearly everything in Qt is done with them, so suggest you read that linked page, and then read it again once finished :) Then apply to your case (e.g. "press add" will raise a signal, you will want a slot on that, and do whatever you want there).

@the-woft Nobody can help you from this description. The link you provide tells you what to do, and also shows it seems that OP had a fault in the program launched. Show the exact command and code you are using. Confirm your OS. There will be no misbehaviour in Qt code, only in what you pass to it and how you handle it.

@Dean21 I just figured this out myself and am just posting in case someone else has the same issue. My function where I want the timer now looks like shown below: QObject::connect(&client, &QMMqttClient::onMessageReceived, [this](const QString &topic, const QByteArray &msg) { ui->Alarm_Triggered_Label->setText("Temperature alarm of PSU triggered, HV output disabled for 5 minutes"); ui->HV_ON_OFF_Button->setEnabled(false); // Use QMetaObject::invokeMethod to execute the code in the main GUI thread QMetaObject::invokeMethod(this, "publishAfterDelay", Qt::QueuedConnection); }); And the call to function publishAfterDelay() looks like shown below: void Widget::publishAfterDelay() { QTimer::singleShot(3000, this, [this]() { client.publishMesage("Alarm_5_min_cooldown_complete", "1"); qDebug() << "timer pinged"; }); } Hope this helps anyone else.

@ChrisW67 Well not as show it is not, the second line in the constructor just uses the one declared in the .h file? Nonetheless, until we see actual code we don't know and it might well be that in fact the second one has a declaration in the constructor as you say....

@TokaraForest In addition to @JonB comments, understand that TCP is always "in order" because it is a stream transport. data is possibly fragmented by the network but is received and assembled in its transmitted order. You don't see the latter parts of the stream until all previous chunks have been received and inserted in the buffer. It seem what you're really asking about is transaction ordering, and that's up to the application as to how you do it. Please make sure to well define a transaction for your protocol. Ambiguities in the "state machine" between client and server will bite you.