I have a QTableWidget with row selection, and i'm trying to treat 3 signals:
cellClicked
cellDoubleClicked
customContextMenuRequested
Things seem to be fine in code: i had in mind the connect syntax, type params are correct and match, etc; and to be more specific, i "know" that the code is correct because i have the following situation:
if i connect the 3 signals to their respective slots, only the single click and the context menú work.
if i connect just one signal each time i compile the code and i run the program, that signal is working well (for the 3 of them).
if i connect the single click signal and the context menu, commenting the connect macro for the double click, they work well. Same for double click and context menu.
BUT if i connect the single click and the double click, the double click is not being treated by my custom slot.
Just to clarify, each signal has a different slot, and as i meantioned above, they work well if i just connect one of them and comment the other 2 in code.
So my question is:
is there any bug with the cellClicked and cellDoubleClick working simultaneously? do i have to set some flag, attribute or whatever that belongs to the QTableWidget?
I'm running out of ideas, thanks for the help!
And also, maybe the code should help:
table and slots declaration:
QTableWidget * table;
public slots:
void tableChange(int row, int column);
void tableChangeDbl(int row, int column);
void PopupMenuTableShow(const QPoint &);
the connects:
connect(table, SIGNAL(cellDoubleClicked(int, int)), this, SLOT(tableChangeDbl(int, int)));
connect(table, SIGNAL(cellClicked(int, int)), this, SLOT(tableChange(int, int)));
connect(table, SIGNAL(customContextMenuRequested(const QPoint &)), this, SLOT(PopupMenuTableShow(const QPoint &)));
Related
In my project, I want to call a variable QImage image generated in the mainwindow.h, in other class files, e.g., called SegSetupDialog.h. Here the image is loaded by clicking a pushbutton in mainwindow.ui, and the SegSetupDialog is a QDialog, which pops up by clicking one pushbutton in mainwindow.ui.
I tried to use a signal-slot connection to send qimage of mainwindow to SegSetupDialog as follows.
For Class MainWindow:
SegSetupDialog *segsetup;
if(image.isNull()==false)
{
emit sendImgData(image);
qDebug()<<"sendImgData emitted!";
if(segsetup==NULL) segsetup = new SegSetupDialog();
connect(this, SIGNAL(sendImgData(QImage)),segsetup,SLOT(getImgData(QImage)),Qt::QueuedConnection);
}
In SegSetupDialog::getImgData
void SegSetupDialog::getImgData(QImage qimage)
{
qImg = qimage;
qDebug()<<"qimage received!";
}
The above connection seems not to work since the qDebug message in getImgData is not printed out. Anyone can help check something wrong with codes, or suggest other methods for accessing image of mainwindow? Thanks!!
You need to do the signal/slot connection before you emit the signal. Connections are done once, usually in the constructor.
However, you should probably do the connect() in the constructor of SegSetupDialog instead of the MainWindow one. It's SegSetupDialog that wants to be notified about image data updates, so you should establish the connection there.
Also, to make sure the signals and slots are specified correctly, don't use Qt 4 connect() calls. Use Qt 5 ones that are checked at compile-time:
connect(this, &MainWindow::sendImgData,
segsetup, &SegSetupDialog::getImgData, Qt::QueuedConnection);
(Of course change it appropriately if you move it to the SegSetupDialog constructor.)
I have copied several buttons in design form. As result all buttons got the same slot for clicked(). How to create and assign new personal slots for buttons?
UPD
Trying to use Signals & Slots editor. It was empty in the beginning, and I added new one:
But if I right click on button btnInfoCB->go to slot.. clicked() , it will point me to the same old method.
Qt creator will create slots for you. From designer, Right click on any push button and select 'Go to slots' option. select Clicked() signal press OK. Qt creator will navigate you to the created slot. Qt automatically connects your button clicked signal to the created slots.
You can do the same for all push buttons you created
Qt has an auto-connect feature that connects the slots named like this: on_UIELEMENTNAME_SIGNALNAME(SIGNAL_PARAMS) with the corresponding signal of the ui element, see the documentation here
So to fix this you have 2 options:
Option 1: rename the slots to have all the names corresponding with the names from .ui file:
private slots:
void on_MyFirstBtn_clicked();
void on_MySecondBtn_clicked();
//and so on
Or use option 2: manually connect
private slots:
//notice the prefix "on_" and the suffix "_clicked()" not part of the function name
void MyFirstBtnClicked();
void MySecondBtnClicked();
And in the constructor of the class (i named it MyWidget) add the connect calls:
connect(ui->MyFirstBtn, &QPushButton::clicked, this, &MyWidget::MyFirstBtnClicked);
connect(ui->MySecondBtn, &QPushButton::clicked, this, &MyWidget::MySecondBtnClicked);
LE: I don't recommend using the UI Designer for connecting slots that are defined in code because of maintainability reasons. That feature in Designer is very good if you need to connect already defined signals and slots, like check/unched to show/hide and other similar predefined functionality, but for your defined slots i don't like it.
New slot for an existing QPushButton /w auto connection
You have to change the objectName of QPushButton first. Then right click and create a new slot connection e. g. clicked(). Qt Creator will then create a new slot with the new objectName e. g. void on_newObjectName_clicked() { }. The old slot is no longer used then and you will get a new fresh function.
Manually connect /w signals and slots editor
If you like to connect it through your editor, you first have to click at the QWidget (e. g. MainWindow) and select change signals/slots from the menu. There you have to add a new function e. g. myNewSlot(), which is then available in the drop-down in the signals and slots editor as shown in your screenshot. If you use this type of connection you need to declare the slot in your .h in private slots and in the .cpp file. The object name may still link to an auto connection, so you probably need to change the objectName as well or remove the auto connected slot.
I'm a beginner in programming in C++/Qt.
I created a widget called wexample in Qt. When displayed, there is an button event that will open another window of the same widget wexample, and so on. My question is how to close all the windows of that widget?
I open my first widget as follows:
wexample *w = new wexample;
w-> show();
Inside the widget, I also have these events:
void wexample::on_pushButton1_clicked()
{
wexample *w = new wexample;
w -> show();
}
void wexample::on_pushButton2_clicked()
{
QWidget::close();
}
So when button 1 is pressed, it will open a new window and so on. When button 2 is pressed, it will close the window where the button is. Is there a way to close all of the windows from that widget all at once? Or even better, is there a way to close specific windows (for example, all the windows after the 3rd one)?
I have tried using signal and slot but I can't connect them since they are all of the same name. I would have to declare all of the widgets beforehand for it to work but I cannot know how many of them the user will need.
I'm sorry if my question isn't clear. I am really a beginner and have been searching for a while but couldn't find an answer. Maybe the structure as a whole doesn't make sense. Please help. Thanks.
You should add your newly created wexample's to a list and then iterate through them when you'd like to close them:
class wexample : public QDialog
{
...
private Q_SLOTS:
void on_pushButton1_clicked() {
wexample *w = new wexample(this);
m_wexamples.append(w);
w->show();
}
void wexample::on_pushButton2_clicked() {
foreach (wexample *w, m_wexamples)
w->close();
}
private:
QList<wexample*> m_wexamples;
};
A few extra points here:
Notice that I added (this) to the wexample constructor above. This ensures that the dialog is properly parented (and therefore will be cleaned up if you don't manually delete the object yourself). Previously, you would have been leaking memory every time you showed the dialog
The slot for the second button simply iterates through the list of dialogs and closes them. This does NOT mean that the dialogs have been deleted (and in fact are still in the list after closing them). If you'd prefer to fully remove them, then use of the "take" methods of QList, removing the dialog from the list and then call dialog->close(); dialog->deleteLater(); on it
This is a somewhat contrived example, you probably won't be opening the dialog from within the dialog's implementation in practice
i have this code but it is not working.i am trying to update progressbar while my video is converting.video conversion is fine but progessbar is not updating
void MainWindow::on_pushButton_clicked()
{
QString alienpath="ffmpeg";
QStringList argument;
argument<<"-i"<<ui->lineEdit->text()<<"/home/suraj/a.flv";
QProcess *alien=new QProcess(this);
alien->start(alienpath,argument);
int p;
p=alien->readAll().toInt();
ui->progressBar->setMaximum(0);
ui->progressBar->setMinimum(100);
ui->progressBar->setValue(p);
}
plz help
First, your progressbar seems to be never updated after it was configured in your code. You may want to use QTimer or readyRead/readyReadStandardOutput signal connecting to some slot in MainWindow or C++11 lambda, but I'm not sure what the output will contain in each time, so I can't tell if this will work.
Second, your toInt() is likely to fail. It works only if your output contains pure number like 67; the application usually produces a lot of output. Use QRegExp or QRegularExpression (Qt5) to extract digits and convert only them. toInt() supports checking if a conversion error has occured, see documentation.
I'm trying to implement QAbstractItemModel for QTreeView. I have problem with inserting rows.
I noticed that if I insert at the beginning of my application all works fine. But If I insert rows later - after some other operations (like selections etc.) new items stay invisible. Moreover QTreeView seems to doesn't work at all! Do I have to emit some signals to notify QTreeView about rows insertion?
This is my insertion method:
bool LayersModel::insertRows(int position, int count, const QModelIndex & parent)
{
LayersModelItem * parentItem = getItem(parent);
if (position > parentItem->childCount())
return false;
beginInsertRows(parent,position,position+count-1);
bool result = true;
for (;count;--count)
result &= parentItem->insertChildren(position, new LayersModelItem());
endInsertRows();
return result;
}
LayersModelItem is class with QList with its children and data.
Full code of my project (KDE libs needed) is here:
https://github.com/coder89/PhotoFramesEditor/tree/v0.0.8
To see the problem select one of blue item on main window and then right-click on it and select "Delete item". (this method is in Canvas::removeItems()) and it is completly commented - I'm desperate and I've tried to find reason of this problem... (in fact it wasn't delete anything - it adds new item).
Thanks for any help & advice!
Just a quick guess, the QT Doc for QAbstractItemModel says...
The model emits signals to indicate
changes. For example, dataChanged() is
emitted whenever items of data made
available by the model are changed.
Changes to the headers supplied by the
model cause headerDataChanged() to be
emitted. If the structure of the
underlying data changes, the model can
emit *layoutChanged() to indicate to
any attached views that they should
redisplay any items shown, taking the
new structure into account*.
So i guess, you need to emit layoutChanged() signal from your model (whenever you change the data in model) in order to update connected views.
Also read the QT docs for model view architecture, how it is implemented in QT
see if that helps, if it doesn't i will try to download your code and debug it and see, what's wrong.
Good Luck