signals-slots

Qt - arguments in signal-slots

I have a QPushButton, QDateEdit and another custom object. I want to connect the button to the date edit object in a way that when I click the button, the date edit object will change its set date to a date defined on the custom object. Kinda like this: connect(pushbutton,SIGNAL(clicked()),dateedit,SLOT(setDate(custom_object.getDate()))...

What is the correct Qt idiom for exposing signals/slots of contained widgets?

Suppose I have a MyWidget which contains a MySubWidget, e.g. a custom widget that contains a text field or something. I want other classes to be able to connect to signals and slots exposed by the contained MySubWidget instance. Is the conventional way to do this: Expose a pointer to the MySubWidget instance through a subWidget() metho...

QxtRPCPeer networked signal/slot example

While being new to Qt, I'm trying to remote control an GUI application with use of QxtRPCPeer. I'm looking for a simple hello world network slider example (one slider in application1 signals setValue() to slider slot in application2), to get the syntax correct. The main goal is similar to a previous question where QxtRPCPeer was recommen...

Qt - Calling widget parent's slots

I wrote a small program to test accessing a widget parent's slot. Basically, it has two classes: Widget: namespace Ui { class Widget; } class Widget : public QWidget { Q_OBJECT public: Widget(QWidget *parent = 0); ~Widget(); QLabel *newlabel; QString foo; public slots: void changeLabel(); private: Ui...

Qt - no such signal error

I'm trying to trigger a signal when a double click happens in one of the draggable widgets on the fridge magnets example. Here's the changes I made to the example source: DragLabel: class DragLabel : public QLabel { public: DragLabel(const QString &text, QWidget *parent); QString labelText() const; public slots: void testS...

Using PyQt signals correctly

A while ago I did some work in Qt for C++; now I'm working with PyQt. I have a subclass of QStackedWidget, and inside that a subclass of QWidget. In the QWidget I want to click a button that goes to the next page of the QStackedWidget. My (simplified) approach is as follows: class Stacked(QtGui.QStackedWidget): def __init__(self, p...

Tying PyQt4 QAction triggered() to local class callable doesn't seem to work. How to debug this?

I create this object when I want to create a QAction. I then add this QAction to a menu: class ActionObject(object): def __init__(self, owner, command): action = QtGui.QAction(command.name, owner) self.action = action self.command = command action.setShortcut(command.shortcut) action.setStatusTip(command.name) ...

Determine signals connected to a given slot in Qt

I've injected myself into a Qt application, and I'm attempting to figure out what signals a given slot is connected to, but can't find any information on doing this. Is there a mechanism for doing this out of the box? If so, is this exposed to QtScript? (If not, I can wrap it easily enough.) If there is no such mechanism, what would ...

Safe Cross Thread Signals/Slot C++

It seem that the only implementation that provide Safe Cross-Thread Signals for both the Signal class and what's being called in the slot is QT. (Maybe I'm wrong?). But I cannot use QT in the project I'm doing. So how could I provide safe Slots call from a different thread (Using Boost::signals2 for example)? Are mutex inside the slot ...

Functions connected to signals in QtScript (on Qt 4.5.2) are not firing

I've injected into a proprietary Qt (4.5.2) application, added my own compatible build of QtScript, and have managed to get access to all the signals I need. However, when connecting to them (via QtScript) my functions are never called. I've come up with a few theories for why this is and I've tested everything I can think of, but I've...

How to Track Emitted Signals in QT?

Is there any way to observe all signals which are emitted? PS. Of course we can write slots for all signals, but that is not I want. Thanks. ...

What exactly are signals and slots in Qt?

I know how they work conceptually, but how are signals and slots implemented in the Qt framework? Qt Creator treats them as keywords, but are they simply a set of macros, or is a special pre-processor required before these source files can be compiled? In other words, if I use Qt's signal/slot features in my code, can I easily compile ...

Does Qt support virtual pure slots ?

Hi, My GUI project in Qt has a lot of "configuration pages" classes which all inherit directly from QWidget. Recently, I realized that all these classes share 2 commons slots (loadSettings() and saveSettings()). Regarding this, I have two questions: Does it make sense to write a intermediate base abstract class (lets name it BaseCon...

How to process signals in a Qt subclass?

How do I process a signal of in a subclass? Let's say my subclass is derived from QTextEdit and is interested in the signal textChanged. It seems silly to connect an object to itself, I should be able to simply override the textChange method -- but it isn't virtual. What is the accepted way to do this? ...

Problem with signals and slots

Using Qt Creator, I am creating a class with custom slots in Qt: class CustomEdit : public QTextEdit { Q_OBJECT public: CustomEdit(QWidget* parent); public slots: void onTextChanged (); }; However, I'm getting thise linker error: undefined reference to 'vtable for CustomEdit' The documentation says: if you get ...

Why is my slot not being called?

I have this class: class CustomEdit : public QTextEdit { Q_GADGET public: CustomEdit(QWidget* parent); public slots: void onTextChanged (); }; CustomEdit::CustomEdit(QWidget* parent) : QTextEdit(parent) { connect( this, SIGNAL(textChanged()), this, SLOT(onTextChanged())); } void CustomEdit::onTextChanged (...

In c++ is there any Events/delegates/interfaces/notifications! anything?

Say i have these classes ViewA and ViewB In objective C using the delegate pattern I could do @protocol ViewBDelegate{ - (void) doSomething(); } then in ViewB interface: id<ViewBDelegate> delegate; then in ViewA implementation i set the delegate: viewB.delegate = self; and now I can call in doSomething from viewB onto any tha...

Resetting Qt Style Sheet

I've managed to style my QLineEdit to something like this: void Utilities::setFormErrorStyle(QLineEdit *lineEdit) { lineEdit->setStyleSheet( "background-color: #FF8A8A;" "background-image: url(:/resources/warning.png);" "background-position: right center;" "background-repeat: no-repe...

Multi-dialog program in PyQT will not close (the sequel!)

Hello everyone. I have another problem with PyQT, this time I have an example that will be far more useful since it contains part of my code (defanged of course!) I have a hard time figuring out how to close the 'PROGRAM SELECT' dialog window by only using the 'LOGOUT' button. I could simply use the close button on the form, but I wan...

Signal - Slot connection inside loop

In my code I am creating new objects of same type inside loop and connecting a signal to object slot. Here is my trial. A * a; QList<A *> aList; int aCounter = 0; while(aCounter < 2) { a = new A; aList.push_back(a); connect(this,SIGNAL(somethingHappened()),aList[aCounter],SLOT(doSometing())); aCounter++; } When somethingH...