I have created a simple UI consisting of a QGroupBox with a bunch of QRadioButtons (32 to be exact) and I want to be able to find the selected one.
I've looked at forums and things, but the answers I've found don't work, and one referenced documentation on a nonexistant method of QGroupBox.
Given the below snippet, how would I find the selected QRadioButton, if any?
QGroupBox* thingGroup = ui->thingGroupBox;
If you want to get it when you select one of them you could use the toogled signal, connect it to some slot and use the sender () function and convert it to QRadioButton.
*.h
public slots:
void onToggled(bool checked);
*.cpp
QGroupBox *thingGroup = ui->groupBox;
QVBoxLayout *lay = new QVBoxLayout;
thingGroup->setLayout(lay);
for(int i = 0; i < 32; i++){
QRadioButton *radioButton = new QRadioButton(QString::number(i));
lay->addWidget(radioButton);
connect(radioButton, &QRadioButton::toggled, this, &{your Class}::onToggled);
}
slot:
void {your Class}::onToggled(bool checked)
{
if(checked){
//btn is Checked
QRadioButton *btn = static_cast<QRadioButton *>(sender());
}
}
I guess it is easier to identify which button is checked using a QButtonGroup, just remember to select buttons in "Design mode" then right-click and select assign to button group :
To identify the checked button, you can use QButtonGroup's checkedButton method:
QAbstractButton *button = ui->buttonGroup->checkedButton();
Related
I have a GUI project in Qt Creator that functions as a shopping list. I am using a QLineEdit to add items to a QTableWidget. The user types something in, presses the QPushButton. The slot then adds a new row to the QTableWidget with the input, in the first column, and a new QPushButton in the second column. I then want the user to be able to press the button and have it clear that row, but I don't know how to access that slot, or sender (I'm not sure the proper term.) Here is the code so far. itemList is my QTableWidget, itemInput is the QLineEdit.
void MainWindow::on_btnAddItem_clicked()
{
ui->itemList->insertRow(ui->itemList->rowCount());
ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
QPushButton *clear = new QPushButton("Clear",this);
ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
ui->itemInput->clear();
}
Here is when the program is initially run. Once they click the button, it runs on_btnAddItem_clicked()
Then it looks like this, and I want to make the clear button remove the row it is a part of.
Do I need to create a new slot? Any help?
You will need to make your own button class and inherit QPushButton. Something like this :
class MyButton : public QPushButton {
public:
MyButton();
QTableWidgetItem *titem;
}
And here you MainWindow :
void MainWindow::on_btnAddItem_clicked()
{
ui->itemList->insertRow(ui->itemList->rowCount());
ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
MyButton *clear = new MyButton("Clear",this);
clear->titem = ui->itemList->item(ui->itemList->rowCount()-1, 0);
connect(clear, SIGNAL(clicked()), SLOT(on_btnClear_Clicked()));
ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
ui->itemInput->clear();
}
void MainWindow::on_btnClear_Clicked()
{
MyButton *btn = (MyButton*)QObject::sender();
ui->itemList->removeRow(btn->titem->row());
}
Please note, it is only step to do it.
I want to know how can I open a popup menu when I right click on the table items. In the popup menu some actions like add and delete should be given, which will create a new row or delete the selected row.
I am a new in the Qt world, so if anybody can give me the full details (with code if possible) then I will be really grateful towards him/her.
Thank you.
My goal: Only in the area of QListWidget and only if you click on an item, the menu with Delete will be opened.
Edit : Ok I solved the problem with the QListWidget and the menu. Now the following must be accomplished:
If you click on an item with the right mouse button, and then click Delete, then the item will be deleted.
My code:
void ProvideContextMenu(const QPoint &); // MainWindow.h
// In MainWindow.cpp
ui->listFiles->setContextMenuPolicy(Qt::CustomContextMenu);
connect(ui->listFiles, SIGNAL(customContextMenuRequested(const QPoint &)),
this, SLOT(ProvideContextMenu(const QPoint &)));
void MainWindow::ProvideContextMenu(const QPoint &pos)
{
QPoint item = ui->listFiles->mapToGlobal(pos);
QMenu submenu;
submenu.addAction("ADD");
submenu.addAction("Delete");
QAction* rightClickItem = submenu.exec(item);
if (rightClickItem && rightClickItem->text().contains("Delete") )
{
ui->listFiles->takeItem(ui->listFiles->indexAt(pos).row());
}
}
Edit2 : Ok I solved the whole problem :D. I uploaded my code, if somebody needs something like that it can help him/her.
Firstly you need to create slot for opening context menu:
void showContextMenu(const QPoint&);
At constructor of your class, which used QListWidget, set context menu policy to custom and connect QListWidget::customContextMenuRequested(QPoint) signal and showContextMenu() slot like this:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
setupUi(this);
listWidget->setContextMenuPolicy(Qt::CustomContextMenu);
connect(listWidget, SIGNAL(customContextMenuRequested(QPoint)), this, SLOT(showContextMenu(QPoint)));
}
Then need to realize context menu opening:
void MainWindow::showContextMenu(const QPoint &pos)
{
// Handle global position
QPoint globalPos = listWidget->mapToGlobal(pos);
// Create menu and insert some actions
QMenu myMenu;
myMenu.addAction("Insert", this, SLOT(addItem()));
myMenu.addAction("Erase", this, SLOT(eraseItem()));
// Show context menu at handling position
myMenu.exec(globalPos);
}
After this we need to realize slots for adding and removing QListWidget elements:
void MainWindow::eraseItem()
{
// If multiple selection is on, we need to erase all selected items
for (int i = 0; i < listWidget->selectedItems().size(); ++i) {
// Get curent item on selected row
QListWidgetItem *item = listWidget->takeItem(listWidget->currentRow());
// And remove it
delete item;
}
}
As you can see we iterate all selected items (for set multiple selection mode use setSelectionMode() method) and delete it by ourself, because docs says that
Items removed from a list widget will not be managed by Qt, and will
need to be deleted manually.
Adding some items is easier, my solution with static variable for different item caption looks like:
void MainWindow::addItem()
{
static int i = 0;
listWidget->addItem(QString::number(++i));
}
To simplify your code use Qt5 sytax for signals and slots. It eliminates the need to create intermediate slots.
I hope it helps to you.
It's much simpler than the accepted answer. You don't need to deal with creating a context menu or cursor positions or any of that. Instead of Qt::CustomContextMenu, use Qt::ActionsContextMenu and just add your actions directly to the widget:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
ui->setupUi(this);
// you can create the actions here, or in designer
auto actInsert = new QAction("Insert", this);
auto actDelete = new QAction("Delete", this);
// you can set up slot connections here or in designer
connect(actInsert, SIGNAL(triggered()), this, SLOT(addItem()));
connect(actDelete, SIGNAL(triggered()), this, SLOT(eraseItem()));
// and this will take care of everything else:
listWidget->setContextMenuPolicy(Qt::ActionsContextMenu);
listWidget->addActions({ actInsert, actDelete });
}
void MainWindow::addItem () {
...; // add an item
}
void MainWindow::eraseItem () {
...; // erase an item
}
Everything above except addActions (I think) can also be done in Designer.
Alternatively, if you don't want to add actual slot functions for whatever reason, you can do everything in a lambda on connect, too:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
ui->setupUi(this);
// you can create the actions here, or in designer
auto actInsert = new QAction("Insert", this);
auto actDelete = new QAction("Delete", this);
connect(actInsert, &QAction::triggered, [=]() {
...; // add an item
});
connect(actDelete, &QAction::triggered, [=]() {
...; // erase an item
});
// and this will take care of everything else:
listWidget->setContextMenuPolicy(Qt::ActionsContextMenu);
listWidget->addActions({ actInsert, actDelete });
}
The signal/slot option is more organized and flexible, but the lambda option is good for short highly specialized bits of code (or binding to functions that aren't slots).
This works for context menus on any widget. Also, the same QAction can be used on multiple widgets.
I have a QListWidget in my MainWindow that displays a list of VideoWidgets (a custom QWidget).
VideoWidget has a clickable label where on clicking the label it should delete a file and then remove the QListItem which holds the VideoWidget from the QListWidget. Here is my VideoWidget class:
VideoWidget::VideoWidget(QWidget *parent) : QWidget(parent)
{
ClickableLabel *smallRed = new ClickableLabel(this)
//...
QObject::connect(smallRed,SIGNAL(clicked()),this,SLOT(removeVideo()));
}
void VideoWidget::removeVideo(){
//...code to remove a file
QListWidget* list = myParent->getList();
QListWidgetItem* item = list->takeItem(list->currentIndex().row());
myList->removeItemWidget(item);
}
The problem is that clicking the smallRed label will not select its item in the QListWidget which means that list->currentIndex().row() will return -1. Clicking anywhere else in the Widget does select the current item. For the code to work I currently have to first click anywhere in the VideoWidget and then click its ClickableLabel. Is there any way I can achieve the same effect with one single click on my ClickableLabel?
From your previous qestion, we suggested use signal and slots. For example:
for(int r=0;r<3;r++)
{
QListWidgetItem* lwi = new QListWidgetItem;
ui->listWidget->addItem(lwi);
QCheckBox *check = new QCheckBox(QString("checkBox%1").arg(r));
check->setObjectName("filepath");
connect(check,SIGNAL(clicked()),this,SLOT(echo()));
ui->listWidget->setItemWidget(lwi,check);
}
Slot:
void MainWindow::echo()
{
qDebug() << sender()->objectName() << "should be remmoved";
}
It is not unique way to solve this problem, but it shows all main things, with signals and slots mechanism, objectName and sender() you can achieve all what you need.
sender() return object which send signal, you can cast it, but if you need only objectName you should not cast.
void MainWindow::addRadioToUI()
{ int button_cunter=4;
while(!database.isEmpty())
{ button_cunter++;
QPushButton *one = new QPushButton("Play: "+name(get_r.getTrackId()));
one->setIcon(QIcon(":/images/play_button.png"));
one->setMaximumWidth(140);
one->setFlat(true);
QGroupBox* get_rGB = new QGroupBox("somethink");
QFormLayout* layout = new QFormLayout;
if(button_cunter%5 == 0){
layout->addWidget(one);
}
get_rGB->setLayout(layout);
scrollAreaWidgetContents->layout()->addWidget(get_rGB);
}
}
I have a few QPushButtons which are added automaticlly.
Is there a way to add "id attribute or sth else" to button and next know which button was clicked? I have different action for each button.
QApplication offers sender() which contains which object sent the signal. So you can do:
//slot, this could also be done in a switch
if(button[X] == QApplication::sender()){
doX();
}else if(button[Y] == QApplication::sender()){
doY();
}
http://doc.qt.io/qt-4.8/qobject.html#sender
QSignalMapper is pretty good for this type of thing.
You would define your slot like this for instance:
public slots:
void clicked(int buttonId); // or maybe trackId
Then add a QSignalMapper* member to your class and connect it to that slot:
signalMapper = new QSignalMapper(this);
connect(signalMapper, SIGNAL(mapped(int)),
this, SLOT(clicked(int)));
In the addRadioToUI, after creating your push button, do:
signalMapper.setMapping(one, button_cunter);
// or trackId if that's more practical
If all you need is a pointer to the object that triggered the signal though, you can use the static QOjbect::sender function in your slot to get a handle to that.
Use QButtonGroup. It takes id as a parameter when a button is added and provides the id to a slot when a button in the group is pressed.
I have a bunch of QComboBoxes in a table. So that I know which one was triggered I remap the signal to encode the table cell location (as described in Selecting QComboBox in QTableWidget)
(Why Qt doesn't just send the cell activated signal first so you can use the same current row/column mechanism as any other cell edit I don't know.)
But this removes all knowledge of the original sender widget. Calling QComboBox* combo = (QComboBox* )sender() in the slot fails, presumably because sender() is now the QSignalMapper.
I can use the encoded row/column to lookup the QComboBox in the table widget but that seems wrong. Is there a more correct way to do it?
e.g.:
// in table creator
_signalMapper = new QSignalMapper(this);
// for each cell
QComboBox* combo = new QComboBox();
connect(combo, SIGNAL(currentIndexChanged(int)), _signalMapper, SLOT(map()));
_signalMapper->setMapping(combo, row);
// and finally
connect(_signalMapper, SIGNAL(mapped(int)),this, SLOT(changedType(int)));
// slot
void myDlg::changedType(int row)
{
QComboBox* combo = (QComboBox* )sender(); // this doesn't work !!
}
EDIT: Added for future search: there is a new book "Advanced Qt Programming" by Mark Summerfield that explains how to do this sort of thing.
Why not connect the QComboBox's signal straight to your slot?
QComboBox *combo = ...
connect(combo, SIGNAL(currentIndexChanged(int)), this, SLOT(changedType(int)));
And then in your slot you can use the sender() method to retrieve the QComboBox that was changed.
void myDlg::changedType(int row)
{
QComboBox *combo = qobject_cast<QComboBox *> sender();
if(combo != 0){
// rest of code
}
}
Alternatively, to use the QSignalMapper method you would just need to change your slot to use the mapping you set up:
void myDlg::changedType(int row)
{
QComboBox *combo = qobject_cast<QComboBox *>(_signalMapper->mapping(row));
if(combo != 0){
// rest of code
}
}
I don't know exact answer, but maybe you should use: QComboBox* combo = qobject_cast(sender()) instead of QComboBox* combo = (QComboBox* )sender(). Someting like this:
QObject* obj = sender();
QComboBox* combo = qobject_cast<QComboBox*>(obj);
if(combo)
{
doSomethingWithCombo(combo);
}
else
{
// obj is not QComboBox instance
}
But maybe QSignalMapper really substitutes itself instead of real sender...