Adding slot for a signal of a widget is easy: right click on it and select "go to slot". But how can I remove the slot created for a button (like on_pushButton_clicked) from the Qt designer.
You have to remove the declaration of <class_name>::on_pushButton_clicked() from header file.
You can press View->Signal/Slot editor, then, a new window will be shown, simply remove the slots by pressings the minus button.
Related
I am using QT 4.8 and C++ and I need a default push button which will be pressed when some text are input in a lineEdit and ENTER key is pressed.
According to the QT document for the property "default" of pushbutton.
the behavior is only for dialogs.
"The default button behavior is provided only in dialogs. Buttons can always be clicked from the keyboard by pressing Spacebar when the button has focus."
How can I have this behavior for a widget, which is a container for all my GUI components.
Thanks.
You can connect the signal QLineEdit::returnPressed() to the slot QAbstractButton::click().
Method 1
from the Designer you simply can:
Right-click on lineEdit
Select "Go to slot..."
Choose returnPressed():
Press ok
In the code view you will see the slot connected to the chosen signal
You can simply call the click() slot of a button you need:
Method 2
You can manually connect signal of any lineEdit to a slot of any pushButton:
In Qt 4 syntax:
connect(ui->lineEdit, SIGNAL(returnPressed()),
ui->anyButton, SLOT(click()));
In new Qt 5 syntax:
connect(ui->lineEdit, &QLineEdit::returnPressed,
ui->anyButton, &QPushButton::click);
I'm currently trying to use Qt Designer to build a GUI and I would like to customize slots of my menu actions.
E-g: I'd like the user to press a menu action and it'd show a widget if it is hidden or hide it if it is already visible.
Basically, what I want to do is execute some code of mine and not the default actions such as show() or hide().
So I'm wondering if I should create a subclass of QMenuBar, add custom slots to it, then create a plugin to use it inside Qt Designer or if I should create a subclass for QMenu or QAction ? Or maybe it isn't the right way to do that ?
I'm working under Visual Studio and I'm only using Qt Designer, not Qt creator.
I'm new to GUI and Qt programming and I'm a bit lost here.
Thanks in advance :)
You have basically 2 options:
Implement the custom logic in the Mainwindow sublcass.
For this, you simply add the slots required for your handling in the class, and make them available in Qt Designer. You can do this:
either in the Signal/Slot editor and click "Modify" and then click on the + Symbol. By this you make new slots available in QtDesigner;
or when your slot is called on_(senderName)_(signalName), Qt autowiring will automatically connect the signals, and you don't have to do this in code or desinger.
Create a QMenuBar subclass and implement the custom logic there.
Your case tell Qt Designer to select your specific subclass as replacement for the default QMenuBar by right-clicking on it, and select "Promote to...". In the new dialog, you can specify your custom class that will be used as replacement in actual code, but in design time a QMenuBar is used. With this mehtod, you don't have to write a separate plugin to make your class available in Qt Designer.
Note that with the second option, your custom logic will only be called when the actions are triggered through the menu bar, not by shortcuts or tool buttons
Create a slot in your class:
onMenuActionTriggered()
Use the connect() to react on action's signal:
connect(ui.myAction, SIGNAL(triggered()), this, SLOT(onMenuActionTriggered()));
In your slot you can do whatever you want.
Another solution (not my favourite one, but possible) is to use the auto-connect functionality, which means, by declaring a slot 'on_myAction_triggered()' (where myAction is the name of your QAction) you don't need to use the connect() since it is automatically connected by Qt
The menu bar is automatically added to any new form derived from QMainWindow (the default when creating a gui application, but you can create new main windows using file->new file or project... and selecting Qt->Qt Designer Form Class ).
To add options to it you simply click in the area labeled "Type here" and write your option text. When you do so an action will appear in a list in the lower part of Qt Designer. Right click on that action and select "go to slot". It will pop up a dialog with "triggered()" already selected for you. Simply click "Ok" and Qt Creator will take care of all the details and transport you to the body of the slot function.
I created the shortcut events, such as:
new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_Q), this, SLOT(close()));
But now I would like to show "Ctrl+Q" in the menu entry here:
How do I do that? I don't seem to find a way to do that in Qt Creator.
You can set the shortcut keys in the QtDesigner in the 'Action Editor' (Tab at the bottom, the 'Signal/Slot Editor' tab is selected by default).
Here all defined QActions are listed. A double click on a field in the 'shortcut' column will open the wanted dialog.
This will add the shortcut to the QAction (create triggered events) and set it as visibile text, e.g. in the menu entry (only visible in the application, not in QtDesigner).
In the 'Property Editor' are more options for the 'shortcuts' (e.g. make them translatable).
Generally you would use QAction class for this, so you would have a QMenu to which you will add actions, in your case CLOSE. Then you can use SetShortcut to add "CTRL + Q" in menu.
pNewAction->setShortcut(QString(strAccel.c_str()));
where pNewAction is of type QAction.
I am writing a Text Editor on Qt Creator. I have a QPlainTextEdit as the central widget, and I want all the font-controlling tools in the main toolbar automatically added to all QMainWindow projects. When I try to drag and drop a QComboBox on to the main toolbar, A not-allowed icon is displayed.
Is there a way of doing this?
Thanks for your help in advance.
You can do what you want by calling the addWidget function of the QToolBar. So if you have called your main tool bar mainToolBar you can do in the constructor of your main window:
QComboBox* myComboBox = new QComboBox;
// Add values in the combo box
ui->mainToolBar->addWidget(myComboBox);
// make the connection between the combo box and a slot
Okay, looking a bit around in the cpp file I realized that I'm referring the wrong thing.
ui->mainToolBar->insertWidget(ui->actionLoadSettings, cbxSelect); will do the trick.
Whenever I use the signal/slot editor dialog box, I have to choose from the existing list of slots. So the question is how do I create a custom named slot?
right click on the main window and select "change signals and slots" and add a new slot.
It will appear in your signal slot editor.
This does seem to be possible in the version of Qt Designer 4.5.2, but it can't be done from the Signal/Slot Editor dock-widget in the main window.
This is what worked for me
Switch to Edit Signals/Slots mode (F4)
Drag and drop from the widget which is to emit the signal, to the widget which is to receive the signal.
A Configure Connection dialog appears, showing the signals for the emitting widget, and the slots for the receiving widget. Click Edit... below the slots column on the right.
A Signals/Slots of ReceivingWidget dialog appears. In here its is possible to click the plus icon beneath slots to add a new slot of any name.
You can then go back and connect to your new slot in the Configure Connection dialog, or indeed in the Signal/Slot Editor dockwidget back in the main window.
Caveat: I'm using PyQt, and I've only tried to use slots added in this way from Python, not from C++, so your mileage may vary...
Unfortunately this is not possible in Qt4.
In Qt3 you could create custom slots which where then implemented in the ui.h file. However, Qt4 does not use this file so custom slots are not supported.
There is some discussion of this issue over on QtForum
I am able to do it by:
In MainWindow.h, add the line:
public slots:
void example();
in the MainWindow class.
In MainWindow.cpp
void MainWindow::example() {
<code>
}
This doesn't seem to be possible in a simple way.
The designer only allows you to promote existing widgets to your own custom widgets. yet it doesn't allow you to connect the signals and slots of the class of promoted widgets.
The way this is possible is creating a plugin for the designer as is described here and in the pages that follow it.
The normal course of action is to promote a widget to your own class and then to connect it manually in your own code. this process is described here
It is not possible to do it, because it means you would add a slot to an existing Qt class like QPushButton which is not really the way to go.
You should create your own QWidget eventually by subclassing an existing one. Then integrating it into Qt Designer as a plugin as suggested. Having your own class allows you to add/modifiy the signals/slots available as you want.
Don't forget about the slot auto-connection features. There are a few drawbacks, like having to rename your function if you rename your widget, but we use those a lot at my company.
You can use the magic slot format of
void on_objectName_signal() {
// slot code here, where objectname is the Qt Designer object name
// and the signal is the emission
}
The connection to this method is established by the method connectSlotsByName and whenever the signal is emitted, this slot is invoked.
Maybe it'll help.
By default you have to choose from the existing list of slots. But you can add slot by right-clicking at you object in the list at right side of designer and choose "slot/signals" and add your custom slot/signal. After that, you can choose it in signal/slot editor.
click the widget by right button
promote the widget into a class you defined
click the widget by right button again
you will see that signal and slot is editable