I am populating a sytem tray icon menu (QMenu) from entries in an xml file which is read when my application starts up.
I am unsure of how to properly set up the SLOT end of the action:
QList<CMenuItem> menuItems = m_layout->getMenuItems();
QListIterator<CMenuItem> iter(menuItems);
while (iter.hasNext())
{
CMenuItem menuItem = iter.next();
QAction *action = new QAction(menuItem.qsTitle, this);
connect(action, SIGNAL(triggered()), this, SLOT(launchMenuItem()));
trayIconMenu->addAction(action);
}
How does my "launchMenuItem()" SLOT know which menu item was triggered? I can't make a SLOT for each menu item as I don't know how many items will exist until run time.
I can think of some ugly ways to do this, but I am looking for the RIGHT way.
What I usually do is to use QAction::setData(const QVariant&) to store whatever action ID I need. Then on slot side I retrieve ID with QAction::data() and behave accordingly.
Note that QVariant obviously accepts much more than basic int (which is what I use to identify actions), you can pass any QVariant-compatible info.
edit : oh! btw, this is somehow ugly because I make use of QObject::sender() to cast triggered action back. Sorry for that, but it works anyway.
Related
I'm creating my first C++ wxWidgets application. I'm trying to create some kind of split button where the options are displayed in a grid. I have a custom button class which, when right-clicked on, opens a custom wxPopupTransientWindow that contains other buttons.
When I click on the buttons in the popup, I want to simulate a left click on the main button. I'm trying to achieve this through events, but I'm kinda confused.
void expandButton::mouseReleased(wxMouseEvent& evt)
{
if (pressed) {
pressed = false;
paintNow();
wxWindow* mBtn = this->GetGrandParent();
mBtn->SetLabel(this->GetLabel());
mBtn->Refresh();
wxCommandEvent event(wxEVT_BUTTON);
event.SetId(GetId());
event.SetEventObject(mBtn);
mBtn-> //make it process the event somehow?
wxPopupTransientWindow* popup = wxDynamicCast(this->GetParent(), wxPopupTransientWindow);
popup->Dismiss();
}
}
What is the best way to do this?
You should do mBtn->ProcessWindowEvent() which is a shorter synonym for mBtn->GetEventHandler()->ProcessEvent() already mentioned in the comments.
Note that, generally speaking, you're not supposed to create wxEVT_BUTTON events from your own code. In this particular case and with current (and all past) version(s) of wxWidgets it will work, but a cleaner, and guaranteed to also work with the future versions, solution would be define your own custom event and generate it instead.
I need to have several shortcuts for one push button. For example Ctrl+W and Enter and Return (Enter and Return are different in Qt), any of them would cause a click on the button. How to do this? If the button was QAction, I would call setShortcuts() ( See Two shortcuts for one action which is NOT a duplicate. It is different, relates to QAction not QPushButton. ) but QPushButton has only setShortcut() (singular), which seems to not allow this. What solution or hack wold you suggest?
OK, I have got a solution which is not that hacky. I can create a QPushButton and a QAction, then set multiple shortcuts for QAction using QAction::setShortcuts() and connect this action to QPushButton::animateClick(). At first this solution did not work because I called connect(action, &QAction::triggered, button, &QPushButton::animateClick);. The problem was with invisible default arguments. QAction::triggered sends true/false indicating whether the action is checked. But QPushButton::animatedClick expects number of milliseconds to remain visually 'pressed'. Therefore it remained 'pressed' only for 0 or 1 millisecond, which is not enough to notice it (the default value of the argument is 100 milliseconds). This can be solved using lambda, hence:
// 'this' refers to a parent widget
auto action = new QAction(this);
action->setShortcuts({ tr("Ctrl+W"), tr("Return"), tr("Enter") });
this->addAction(action);
auto button = new QPushButton(tr("Hey, click me!"));
connect(action, &QAction::triggered, [button](){ button->animateClick(); });
And that's it.
I have one QTableWidget with some QTableWidgetsItems on it. Some items use checkboxes. I've added the checkboxes using the follow code:
QTableWidgetsItem->setCheckState(Qt::Checked);
I would like now to call some function when this checkbox state change. Using a signal for example.
What may be the easiest way to accomplish this?
The easiest way to do this is to capture signal(s) of QTableWidget with slot(s) in the class that contains QTableWidget. While it would seem that QTableWidget::itemActivated might be our best bet, it is uncertain whether or not this is emitted when the Qt::CheckState is equal to Qt::Checked. In addition, even if this was true, the signal would not provide you the capabilities of handling item unchecking which your application may need to do.
So, here is my proposed solution. Capture the QTableWidget::itemPressed and QTableWidget::itemClicked signals with slots defined in the class that contains the QTableWidget. As itemPressed should be called BEFORE the mouse button is released, and itemClicked should be called AFTER the mouse button is released, the Qt::CheckState for that QTableWidgetItem should only be set in between these two signal emissions. Thus, you can determine exactly when a QTableWidgetItem's checkState has changed with low memory overhead.
Here is an example of what these slots could look like:
void tableItemPressed(QTableWidgetItem * item)
{
// member variable used to keep track of the check state for a
// table widget item currently being pressed
m_pressedItemState = item->checkState();
}
void tableItemClicked(QTableWidgetItem * item)
{
// if check box has been clicked
if (m_pressedItemState != item->checkState())
{
// perform check logic here
}
}
And the signals/ slots would be connected as follows:
connect(m_tableWidget,SIGNAL(itemPressed(QTableWidgetItem *)),this,SLOT(tableItemPressed(QTableWidgetItem *)));
connect(m_tableWidget,SIGNAL(itemClicked(QTableWidgetItem *)),this,SLOT(tableItemClicked(QTableWidgetItem *)));
Where m_tableWidget is the QTableWidget * you associate with your table widget.
class genericTaskList : public QListWidget
{
Q_OBJECT
public:
QListWidgetItem *defaultText;
genericTaskList (QWidget *parentWidget)
{
setParent (parentWidget);
setFixedSize (445, 445);
defaultText = new QListWidgetItem ("Double click here to compose the task");
defaultText->setFlags (defaultText->flags () | Qt :: ItemIsEditable);
insertItem (0, defaultText);
QObject :: connect (this, SIGNAL (currentRowChanged (int)), this, SLOT (addDefaultText (int)));
}
public slots:
void addDefaultText (int rr)
{
std::cout << "\ndsklfjsdklfhsdklhfkjsdf\n";
insertItem (++rr, defaultText);
}
};
This code is supposed to issue a signal each time the row gets edited.
After I call "insertItem" in the constructor, the signal is issued.
But, that's it. It never gets issued after that - no matter how many times I edit the row.
What am I missing?
At first it seems like QListWidget::itemChanged is the way to go, but soon you run into a problem: the signal is sent for everything - inserts, removes, changing colors, checking boxes, etc! So then you end up trying to put in flags and filter everywhere by intercepting various signals to find out if editing was the actual event. It gets very messy.
There is also QAbstractItemModel::dataChanged , which would seem like a good solution. It even has a parameter "const QVector& lstRoles" so you could scan for Qt::EditRole and see if it was really edited. Alas, there's a catch - it gets called for everything just like QListWidget::itemChanged and unfortunately, for QListWidget anyway, the roles parameter is always empty when it's called (I tried it). So much for that idea...
Fortunately, there's still hope... This solution does the trick! :
http://falsinsoft.blogspot.com/2013/11/qlistwidget-and-item-edit-event.html
He uses QAbstractItemDelegate::closeEditor, but I prefer using QAbstractItemDelegate::commitData.
So make a connect like so...
connect(ui.pLstItems->itemDelegate(), &QAbstractItemDelegate::commitData, this, &MyWidget::OnLstItemsCommitData);
Then implement the slot like this...
void MyWidget::OnLstItemsCommitData(QWidget* pLineEdit)
{
QString strNewText = reinterpret_cast<QLineEdit*>(pLineEdit)->text();
int nRow = ui.pLstItems->currentRow();
// do whatever you need here....
}
Now you have a slot that gets called only when the list item's text has been edited!
currentRowChanged indicates the row selection has changed, not the content of the row. Perhaps you want to use currentTextChanged or itemChanged instead.
The reuse of the word current and changed in the QT docs is quite confusing.
Warning: A QListWidgetItem can only be added to a QListWidget once. Adding the same QListWidgetItem multiple times to a QListWidget will result in undefined behavior.
So even if it will emit the signal I think you should better to add newly created Item.
And when do you want the new row to be inserted ? -
as soon as item is double clicked or finishing edit - they differ.
I have a Qaction on a menu item for deleting selected items in one of my views. Here is how i create the action:
deleteAct = new QAction( tr("Delete Selected"), this);
deleteAct->setShortcut(QKeySequence::Delete);
connect(deleteAct, SIGNAL(triggered()), this, SLOT(deleteSelected()));
I setup a keyboard shortcut (Delete Key) which should trigger the delectAct action. It works most of the time but at some points it stops working... Does anyone know why the shortcut would stop working?
Note: the action still works if i trigger it from the menu item. Its just the shortcut that doesn't...
You need to add the action to a widget, since it's the widget that will be listening for key events.
Assuming "this" is a mainwindow, simply do
addAction(deleteAct);
Note that you can add the same action to multiple widgets (that's the whole point of the separated action concept). So it's fine to add it to the mainwindow and to a menu.
Try changing the shortcut context of the action, for example:
deleteAct->setShortcutContext(Qt::ApplicationShortcut);
The shortcut works depending on the focus of the application views.
I wanted to have shortcuts working on buttons.
In my application I changed the shortcut context of the action,
added the action to the widget
and finally to the subviews of the application.
Then the necessary signals and slots of widget an action must be connected.
const QAbstractButton*button = dynamic_cast<QAbstractButton*>(widget);
action->setShortcutContext(Qt::WidgetWithChildrenShortcut);
widget->addAction(action);
ui->textBrowser->addAction(action);
ui->treeSource->addAction(action);
if (button)
{
if (button->isCheckable())
{
action->setCheckable(true);
if (button->isChecked()) action->setChecked(true);
connect(action, SIGNAL(triggered(bool)), button, SLOT(setChecked(bool)));
connect(button, SIGNAL(clicked(bool)), action, SLOT(setChecked(bool)));
}
else
{
connect(action, SIGNAL(triggered()), button, SLOT(click()));
}
}
Without seeing the complete code, I'd hazard a guess that somewhere it gets enabled/disabled. Make sure that the shortcut is getting hit in the constructor and not 'disabled' somewhere else because of a setting perhaps.
You can use http://doc.qt.io/qt-5/qaction.html#shortcutVisibleInContextMenu-prop property since QT 5.10 for this:
deleteAct->setShortcutVisibleInContextMenu(true);