I am practicing some GUI programming. I would like to scroll 2 qtextedit at the same time.
my problem is i could not find the SIGNAL for verticalscrollbarvaluechanged.
connect(ui->textEdit,SIGNAL(....),this,SLOT(scroll());
i have this code for the SLOT
void MainWindow::scroll()
{
ui->textEdit->verticalScrollBar()->valueChanged(ui->textEdit2->verticalScrollBar()->value());
ui->textEdit2->verticalScrollBar()->valueChanged(ui->textEdit->verticalScrollBar()->value());
}
also is there a way to hide the scrollbar? just make it look transparent, but it still there?
thank you
You must not create a new slot, you must use the signal of a scrollbar with the slot of the other and vice versa.
connect(ui->textEdit->verticalScrollBar(), SIGNAL(sliderMoved(int)), ui->textEdit_2->verticalScrollBar(), SLOT(setValue(int)));
connect(ui->textEdit_2->verticalScrollBar(), SIGNAL(sliderMoved(int)), ui->textEdit->verticalScrollBar(), SLOT(setValue(int)));
Related
I have a programm with a QLabel, QTextEdit and a QPushButton.
I want to put the text from LineEdit to Label when I click the button.
I can do that by creating my own slot but can it be done with Qt slots?
I've tried this code but it works not as I want...
this->connect(pushButton ,SIGNAL(clicked()), lineEdit, SIGNAL(textChanged(QString)), Qt::QueuedConnection);
t->connect(lineEdit, SIGNAL(textChanged(QString)) , label ,SLOT(setText(QString)), Qt::DirectConnection);
If you need to force the user to push a QButton for "applying" the text he/she typed in a QTextEdit to a QLabel, maybe you want to check the validity of the inserted text, or use the text to achieve some goal or to store it in a variable for later use... so you need a custom slot or a custom class.
Instead you can connect the signal QTextEdit.textChanged(QString) to the slot QLabel.setText(QString), so everything is typed in the QTextEdit is sent to the QLabel without pushing a button.
But all depends on your aim.
Here's how I would do it:
connect(ui->pushbutton, SIGNAL(clicked()), this, SLOT(slot_pushbutton_clicked()))
And then in the the slot_pushbutton_clicked slot,
ui->label->setText(ui->lineEdit->text)
Hope it helps :)
Having the hardest time setting up signal and slot macros for variables in main. It is extremely easy to do when the variables are located in classes, but how do you do this when you want to connect a variable in main?
I have two radio buttons in main as follows:
QRadioButton *btn_ledWhite = new QRadioButton;
QRadioButton *btn_ledBlack = new QRadioButton;
I want to pass these buttons to a function that sets their stylesheet. Something like below:
btn_led->setStyleSheet("QRadioButton::indicator::unchecked{background-color:gold;}");
When the user of my application presses btn_start, the white player's LED should light up. Unfortunately, I cannot pass the buttons from main to signal and slot macros. I want something like this:
QObject::connect(btn_start, SIGNAL(clicked()), whiteClock, SLOT(updateLED(btn_ledWhite)));
This is illegal qt syntax, however. Apparently, you cannot pass an argument to a function wrapped in a SLOT macro.
You can do something like:
Counter a, b;
QObject::connect(&a, SIGNAL(valueChanged(int)),
&b, SLOT(setValue(int)));
... but I cannot mix the presentation (GUI) layer, with the business layer (i.e. standard 3-tier architecture model... think MVC). Else I would just stick this button in a class and not worry make this thread.
Does anyone have idea how to connect a variable in main with a signal and slot macro?
You can use a QSignalMapper for this.
You connect your buttons' clicked() signal to the mapper's map() slot, then set the mapping from button to led with the mapper's setMapping function.
Once that's done, connect the mapper's mapped signal to your whiteClock. You might need to adjust your slot function's signature to take a QWidget rather than a QPushButton, but if all you need is to call setStyleSheet, then that's not much of a problem.
This code works. You do need to adjust the function signature as previously mentioned to a QWidget*, instead of a QRadioButton*...but everything else should be the same.
main.cpp
QSignalMapper * signalMapper = new QSignalMapper;
//Start game, start white's clock, turn on white's LED
QObject::connect(btn_start, SIGNAL(clicked()), whiteClock, SLOT(startClock()));
QObject::connect(signalMapper, SIGNAL(mapped(QWidget*)), whiteClock, SLOT(updateLED(QWidget*)));
QObject::connect(btn_start, SIGNAL(clicked()), signalMapper, SLOT(map()));
signalMapper->setMapping(btn_start, btn_ledWhite);
Set the stylesheet in your clock class and you're good to go.
In QML you can do the on click event. I am writing my qml in C++, however there is no onclick method.
How do you get the on click to work.
Button *btnSave = new Button();
btnSave->setText("Save");
contentContainer->add(btnSave);
Does anyone have a simple example that they could provide to get me started?
Thanks in advance.
To do this in C++, you have to connect a signal (in this case, is the Button's clicked() to a slot of your class). You better take a look here.
Supposing you defined a slot called onSaveButtonClicked() in your header, that will be called when your button is clicked:
public slots:
void onSaveButtonClicked();
in your application class, after create your button, you'd have to do:
connect(btnSave, SIGNAL(clicked()), this, SLOT(onSaveButtonClicked()));
When your button is clicked, it will emit the signal that will call the slot function.
I'm using Qt 4.7 on Windows 7 Ultimate 32 bit.
The QMainWindow of my program has a QDockWidget. I've noticed that if I minimize the main window by the minimize button on the title bar, after restoring it the dock widget is closed. I didn't write any support for a feature like this!
How does this happen and how to prevent this?
Thanks.
I encountered this error when writing my own application. I have QDockWidget with options for my application. Using Qt Creator I created menu with QAction actionMenu which was checkable. Then I connected QDockWidget and QAction like this:
QObject::connect(ui->dockWidget, SIGNAL(visibilityChanged(bool)),
ui->actionMenu, SLOT(setChecked(bool)));
QObject::connect(ui->actionMenu, SIGNAL(toggled(bool)),
ui->dockWidget, SLOT(setVisible(bool)));
The order of connection is not important. And then when I minimized application with QDockWidget being visible, after I restored it QDockWidget was closed and actionMenu was unchecked.
In fact there are two solutions. First which works for me is to use SIGNAL(triggered(bool)) instead of SIGNAL(toggled(bool)):
QObject::connect(ui->dockWidget, SIGNAL(visibilityChanged(bool)),
ui->actionMenu, SLOT(setChecked(bool)));
QObject::connect(ui->actionMenu, SIGNAL(triggered(bool)),
ui->dockWidget, SLOT(setVisible(bool)));
The second solution uses action which you can obtain from QDockWidget:
// Retrieve action from QDockWidget.
QAction *action = ui->dockWidget->toggleViewAction();
// Adjust any parameter you want.
action->setText(QString("&Menu"));
action->setShortcut(QKeySequence(Qt::CTRL + Qt::Key_M));
action->setStatusTip(QString("Press to show/hide menu widget."));
action->setChecked(true);
// Install action in the menu.
ui->menuOptions->addAction(action);
I know for sure that SIGNAL(toggled(bool)) was causing in my application closure of QDockWidget.
I faced the same problem... I managed to get rid of it by using a method called StoreWindowsLayout and RestoreWindowsLayout.
StoreWindowsLayout will save the content of the ByteArray returned by the Method QMainwindow::saveState().
RestoreWindowsLayout will restore that bytearray, and therefore your windows layout, the qdockwidget visibility state and so on...
I call StoreWindowsLayout on ApplicationMainFrm::changeEvent, on ApplicationMainFrm::closeEvent (it's likely this one you'll need) and in ApplicationMainFrm::hide().
Then I use restoreWindowsLayout in ApplicationMainFrm::showEvent.
Exemple of use of restoreWindowsLayout in my MainForm :
void ApplicationMainFrm::showEvent(QShowEvent* pEvent)
{
QMainWindow::showEvent(pEvent);
restoreWindowsLayout();
}
Hope it helps !
Hi I've got a spare moment so decided to look at Qt and how easily I can port my windows applications to Qt.
My only real problem is a couple of controls that will need re-implementing under Qt. I've already handled the basic drawing of the control but my control creates a child scroll bar. The problem is that this scrollbar is created dynamically as part of my new Widget (i.e. m_Scrollbar is a member of the widget). How can I then respond to movement of the scrollbar. Under other circumstances this is easy as I'd just create an on_myscrollbar_sliderMoved function under my protected slots and handle it there. This does however rely on the QScrollBar being called myscrollbar. As I've created the object dynamically (i.e. not through designer) how do I capture this signal?
I'm guessing this is really simple and I'm missing the obvious :)
connect( myScrollbar, SIGNAL( <signal signature>), this, SLOT( <slot signature>));
Call connect after creating the scroll bar (I presume that you need this signal handling immediately after creating the scroll bar).
I assumed myScrollbar is of type QScrollBar* and that the slot is defined as a member in your class.
When myScrollbar is destroyed, the connection is removed (disconnect is called).
See the documentation of QObject::connect and QObject::disconnect methods.
Later edit - to be more concrete, in your code it could be:
myScrollbar = new QScrollBar; // Create the scroll bar
// ... add it to the layout, etc.
// ... and connect the signal to your slot
connect( myScrollbar, SIGNAL( sliderMoved( int)), this, SLOT( handleSliderMoved( int)));
where handleSliderMoved is the slot method of your class.