signals-slots Questions

1

I have my first Qt application in development. It's a desktop client for site messaging. Qt documentation says that i need to have only one instance of QNetworkAccessManager accross application. B...
Tsarina asked 5/9, 2017 at 13:55

2

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I have a class server for which I have created a signal joined(QString name). I call it in a function called join(QString name), however I'm getting the error Server.o: In function Server::join(...
Neomineomycin asked 16/11, 2012 at 2:1

3

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I am trying to run a command line program, gphoto2 from my Qt app running on Linux, and read the results that it outputs to Standard Output and Standard Error. The GUI in this proof of concept prog...
Prewar asked 21/9, 2012 at 16:23

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Connecting a QML signal to a regular C++ slot is easy: // QML Rectangle { signal foo(); } // C++ old-style QObject::connect(some_qml_container, SIGNAL(foo()), some_qobject, SLOT(fooSlot()); // wo...
Arthur asked 25/3, 2013 at 21:8

1

I have a Microsoft visual studio application that is grabbing frames from cameras and I am trying to display those frames in a Qt application. I am doing some processing with the frames using OpenC...
Persimmon asked 10/7, 2017 at 13:21

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I'm not sure if something like this is possible, but I am attempting to dynamically generate a GUI based on properties that have been registered into Qt's property system. My assumption is that sin...
Dagenham asked 13/9, 2013 at 19:23

4

Is it possible to have a template class, which inherit from QObject (and has Q_OBJECT macro in it's declaration)? I would like to create something like adapter for slots, which would do something,...
Bennie asked 9/12, 2010 at 11:0

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I recently came across a problem with my code that was caused by certain behaviours being dependent upon the signal-slot connection order in a particular object. This is a design flaw on my behalf ...
Historicity asked 24/12, 2011 at 14:4

6

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Can someone explain in simple terms the "signals and slots" pattern?
Sloane asked 23/11, 2008 at 20:12

4

I am developing a scientific data acquisition application using Qt. Since I'm not a deep expert in Qt, I'd like some architecture advise from the community on the following problem: The applicatio...
Amorino asked 15/3, 2010 at 21:58

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I don't quite understand how the Qt::UniqueConnection 'flag' works. The Qt::UniqueConnection is a constant from the enum Qt::ConnectionType that "describes the types of connection that can be used...
Chamois asked 30/3, 2017 at 15:3

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I can emit signals with structs tagged with Q_GADGET from C++ to QML. Is it possible send such a struct from QML to a C++ slot? My code fails on the first step: creating an instance in QML. This ...
Era asked 14/3, 2017 at 21:59

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My main application object is a QObject, that juggles a QSystemTrayIcon, a QDialog, a QWindow and a few other components. The app mostly sits in the tray, with some options dialogs etc etc. Now, I...
Breechblock asked 18/10, 2009 at 20:50

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I am connecting lambdas to QObject's signals: QObject::connect(handle, &BatchHandle::progressMax, [this](const ProcessHandle* const self, const int value) { this->maxProgress(value); });...
Spatterdash asked 10/2, 2017 at 14:42

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I have such class: #include <QObject> namespace taservices { class ProcessHandle : public QObject { Q_OBJECT public: ProcessHandle(const void* const processContextPointer, const QString...
Edme asked 10/2, 2017 at 15:43

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In my code I emit a signal mySignal and I want to wait for the end of a connected slot mySlot execution before it continues: emit mySignal(); // Wait for the end of mySlot execution... // Some cod...
Condottiere asked 1/2, 2017 at 16:41

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I have encountered quite freaky bug - QAction::trigger caused blocking dialog to appear, which caused my server which called trigger to go stuck (eg. not able to process socket signals until dialog...
Frigging asked 27/1, 2017 at 15:57

1

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I have a variable t t = 0 I want to start an event whenever t value is changed. How ? There's no valuechanged.connect properties or anything for variables...
Asperity asked 26/1, 2017 at 3:4

2

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I recently started using qt to build a python GUI. I have two problems I can't quite find the solutions to. the code below is a sample of what I need to build. 1: Check which radio button from a l...
Rudder asked 25/1, 2017 at 0:28

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I am trying to get drag and drop (with images or files) working for my listwidget in pyqt5. I can find a lot of examples with pyqt4, but there is one part that does not work in the newer version: ...
Nicks asked 12/1, 2017 at 10:12

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Is there a way curry qt slot? Maybe there is something similar to curryng?
Degradation asked 24/1, 2011 at 16:16

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This is a class which form i made in qt5 designer. The slot is called twice when I click the button. class CustomerList(QWidget, Ui_CustomerList): def __init__(self, parent=None): QWidget.__init...
Jotting asked 3/12, 2016 at 8:37

2

I am trying to connect to the selectionChanged signal of a QTreeView using PyQt. I have done this in the past (for a QTableView) and was successful. But now I cannot get similar code to work. In t...
Bel asked 11/11, 2010 at 22:58

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I'm doing some multi-threading. I have a worker class with a work method, which I send into a separate QThread. The work method has a conditioned while loop inside. I want to be able to send a sign...
Convector asked 11/10, 2016 at 11:32

1

This is only my second question here so please do bear with me. I have a python script that currently contains two classes. One of which manages a GUI and the other is my 'worker thread' (a pyqt th...
Intrastate asked 8/10, 2016 at 14:31

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