Hi i try to bind slot with argument to QAction triggered SIGNAL
i have this code ,the context menu working great . BUT the OpenPublishWin never triggered .
void MyApp::ShowContextMenu(const QPoint& pos) // this is a slot
{
QString groupID;
QPoint globalPos = ui.treeView_mainwindow->mapToGlobal(pos);
QModelIndex modelIndx = ui.treeView_mainwindow->indexAt(pos);
groupID = modelIndx.model()->index(modelIndx.row(),0,modelIndx.parent()).data(Qt::UserRole).toString();
QMenu myMenu;
OpenPublishAction = new QAction(tr("Send"), this);
myMenu.addAction(OpenPublishAction);
connect(OpenPublishAction, SIGNAL(triggered()),m_SignalMapper, SLOT(map()) );
m_SignalMapper->setMapping(OpenPublishAction,groupID);
connect(m_SignalMapper, SIGNAL(mapped(QString)), this, SLOT(OpenPublishWin(QString)));
QAction* selectedItem = myMenu.exec(globalPos);
}
void MyApp::OpenPublishWin(QString gid)
{
WRITELOG(gid)
}
A quick look at the Qt docs for QSignalMapper (assuming that is what you're using based on the question title) states that the parameter for the mapped signal is const QString&. I can't recall if the parameter needs to be exact in this case for the connection but it may be a factor.
Additionally, double check that your connects are being made by wrapping them in an assert or some form of verify. Qt will also print out to the console if a connection cannot be made.
Related
I need to develop a Sudoku game. After reading a text file containing the number values, I create 9*9 widgets.
If (the value is already set then I instantiate to a qlabel containing the number,
else I instantiate a combobox containing the possible values of each case).
Until here everything is OK.
The problem is that when a value is chosen from the combobox, I need to draw it in a square in my view (MVC). The problem is how can I know which one was chosen?
The only signal can I use from combobox signals is currenttextchanged(QString), but I'll not know which combo made that signal.
The ideal for me would be something like this SIGNAL(curretextchanged(QString, int, int)), but I don't know if I can define a new signal?
Here is some code:
QWidget *tab[9][9];
SudModel *modele = ???;
QComboBox *combobox = new QComboBox();
combobox->setStyleSheet("border: 1px solid red");
int tmp = modele->valuesof(i, j).size();
for (int s = 0; s < tmp; s++) {
combobox->addItem(QString::number(modele->valuesof(i, j)[s]));
}
connect(combobox, SIGNAL(currentTextChanged(QString)), this, SLOT(update()));
tab[i][j] = combobox;
One solution would be to attach that extra information when you connect to the signal for a specific combobox.
For example, say you have your function update(QString text, int x, int y) then you could attach the signal to a lambda that calls the function with the extra arguments, captured at connect time. Something like this:
connect(combobox, &QComboBox::currentTextChanged, [x, y, this](const QString& text){ this->update(text, x, y); });
That would then call the update functions with the x and y values captured when the connection was made along with the text argument that originated from the signal.
You can ask the slot for a sender()
QObject *QObject::sender() const
Returns a pointer to the object that sent the signal, if called in a
slot activated by a signal; otherwise it returns 0. The pointer is
valid only during the execution of the slot that calls this
function from this object's thread context.
You can use QSignalMapper.
In this you map every item with mapper with any specific string. Now when any mapped item emits signal you can know which item emitted it by the string.
You can use the same with minor changes like using Signal 'currentTextChanged' as mentioned. But the same result can be obtained by using 'currentIndexChanged' signal with some modifications.
signalMapper = new QSignalMapper(this);
for (int i = 0; i < 2; ++i) {
QComboBox *combo = new QComboBox();
connect(combo, SIGNAL(currentIndexChanged()), signalMapper, SLOT(map()));
signalMapper->setMapping(combo, "combo" + i);
}
connect(signalMapper, SIGNAL(mapped(QString)),
this, SIGNAL(indexChanged(QString)));
NOTE : (source Qt Assistant)
QSignalMapper class collects a set of parameterless signals, and
re-emits them with integer, string or widget parameters corresponding
to the object that sent the signal
I have a QComboBox in one of the columns of a QTableView. How can I change the other columns depending on what I selected in the ComboBox? I am using the QComboBox as a delegate.
There are at least 2 approaches.
Use natural for Qt's model itemChanged signal.
emit signal from your delegate and catch it inside your main window.
If your delegate is standard which means that inside setModelData() method you have something like:
QComboBox *line = static_cast<QComboBox*>(editor);
QString data = line->currentText();
//...
model->setData(index, data);
then I think you should use just natural way. For example:
connect(model,&QStandardItemModel::itemChanged,[=](QStandardItem * item) {
if(item->column() == NEEDED_COLUMN)
{
//you found, just get data and use it as you want
qDebug() << item->text();
}
});
I used here C++11 (CONFIG += c++11 to .pro file) and new syntax of signals and slots, but of course you can use old syntax if you want.
I already reproduced your code(delegate with combobox) and my solution works if I select something in combobox and confirm that by enter clicking for example. But if you want to get solution where data will be changed automatically, when you select another item in combobox(without pressing enter) then see next case:
Create special signal onside delegate:
signals:
void boxDataChanged(const QString & str);
Create connection inside createEditor() method:
QWidget *ItemDelegate::createEditor(QWidget *parent,
const QStyleOptionViewItem &option,
const QModelIndex &index) const
{
QComboBox *editor = new QComboBox(parent);
connect(editor,SIGNAL(currentIndexChanged(QString)),this,SIGNAL(boxDataChanged(QString)));
return editor;
}
And use it!
ItemDelegate *del = new ItemDelegate;
ui->tableView->setItemDelegate( del);
ui->tableView->setModel(model);
connect(del,&ItemDelegate::boxDataChanged,[=](const QString & str) {
//you found, just get data and use it as you want
qDebug() << str;
});
I have a QStandardModel. I connect its itemChanged signal to my own slot.
m_model = new QStandardItemModel(this);
connect(m_model, SIGNAL(itemChanged(QStandardItem*)), this, SLOT(changed(QStandardItem*)));
The slot looks like this:
void Class::changed(QStandardItem * item) {
// ui->pushButton->setText("change");
QString name = item->parent()->data().toString();
ui->pushButton->setText(item->data().toString());
}
The pushButton text will change to "change", so my slot seems to work. However, item->data().toString() is always empty.
How do I do this right?
I think you should use QStandardItem::text() method. Like this: QString name = item->parent()->text();
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...