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Questions tagged [qt-connection]

23 questions
35
votes
3 answers

My signal / slot connection does not work

I repeatedly see people having problems with slots not being called. I would like to collect some of the most common reasons. So maybe I can help people and avoid a lot of redundant questions. What are reasons for signal / slot connections not…
Silicomancer
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1 answer

use of undeclared identifier 'connect'

I'm trying to write a simple downloader in qt. It's based on this example: http://www.ggkf.com/qt/qnetworkrequest-to-download-an-image downloader.cpp: void Downloader::GetImage( QString _url, QNetworkAccessManager *qnam ) { connect( qnam,…
btzs
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1 answer

Qt Subclassing and "No matching function for call to connect"

I am trying to encapsulate table view behavior and I am starting with connecting the table view header signals to table view slots defined in the subclass. I can get the behavior I'm looking for without subclassing, but that defeats the purpose.…
Jason deMello
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2
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2 answers

How does Qt::DirectConnection act when used in multi-threaded environment?

Though Qt::QueuedConnection or Qt::AutoConnection (in certain cases) are preferred in a multithreaded environment, I am asking this question for my understanding purpose. If signal MySignal() is emitted in thread A & slot MySlot() belongs to object…
iammilind
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1 answer

How to call defined slots from keypress event in qt / How to connect keypressed event with QPushbutton on gui?

I am beginner to qt. I was working on calculator gui application, I have already defined slots like numPressed() when any of the number pushbutton is pressed on the calculator that will be displayed on the lineEdit. void Calculator::numPressed(){ …
Karthikgr
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1 answer

How to pass a std::function or a function pointer into qtconnect?

This is mainly to clean up a bunch of code from my constructor. I have around 20+ lines of connect(object, func1, this, func2) in the constructor alone and I am trying to clean up the code by having a…
Sailanarmo
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1 answer

QT connect no matching function to call to

I know there are already some threads for this question but I think I made none of the mistakes others did which led to the problem. So here is my code: #include "consolerender.h" consoleRender::consoleRender(QObject *parent) : QObject(parent)…
ShivaDef
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2 answers

Qt - modify slot's parameter of previous connected signal using lambda function

I'm trying to reconnect a signal to the same slot but with a different parameter. This would work if I just wanted to reconnect the same signal to a diferent slot without using parameters or lambda functions but I need to do it this way. At first I…
RubenC
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2 answers

c++ qt QObject:: connect: No such slot

I have defined my slot like this: void choixPoints:: prendpixel1(Pixel depart) { //... } and I want to execute the following sentence: Pixel depart= picmou->define(); //definition of a pixel, well defined connect(chp3, SIGNAL(clicked()), this,…
user2269556
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1 answer

My QT connect works from parent to child, but not vice versa

I am making a QT application. I have a MainWindow1 class and a FirstTab class. The MainWindow1 class is a QMainWindow and inside I created this signal -> mainwindow1.h signals: void loadDateSig(QString strDate); And in FirstTab I created this…
Xenomorphing
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2 answers

Can't use Qt::UniqueConnection in Qt Connect

I have a connect statement that compiles fine, with the connection type QueuedConnection. Once I OR it with UniqueConnection, it refuses to compile. I had to re-cast it back to Qt::ConnectionType for it to run. Is this normal/expected…
TSG
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3 answers

How to connect two QComboBox so that the second shows only certain items?

I have two QComboBoxes to connect with each other. In particular, I'd like that if a scaling is made in the first QComboBox, this is not also shown in the second QComboBox and vice versa. This is my code: auto lingua_originaleT = new…
Gretaas
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1 answer

I cannot use the pointer from QMainWindow as argument in connect for QT5

This code creates a thread and connect it to MainWindow in QT. void UI_handling::create_thread_for_looping_terminal(){ loop_terminal_thread = new Loop_terminal_thread(mainWindow, &j1939); loop_terminal_thread->start(); …
euraad
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2 answers

Qt | C++ connect not being triggered

I'm trying to play with basic signal/slot in C++. Here is my Network-Manager, which will trigger the event: class NetworkManager : public QObject { Q_OBJECT public: explicit NetworkManager(QApplication* application); void…
Maifee Ul Asad
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1 answer

Problem with connecting QLabel to QSlider

I have a problem. I've created a class, in which I have a slider and a label. I want to connect these with the QObject::connect, but when I do it, nothing happens. Can you tell me what am I doing wrong? My class: class Loads :public QObject { …
donefun
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