I didn't manage to select the first item of the completer when the popup is displayed in PopupCompletion mode.
My current code that doesnt work:
completer->setCompletionPrefix(text);
QItemSelectionModel* sm = new QItemSelectionModel(completer->completionModel());
sm->select(completer->completionModel()->index(0,0), QItemSelectionModel::Select);
completer->popup()->setSelectionModel(sm);
Any suggestions?
I would try changing the order of the last 2 lines:
completer->popup()->setSelectionModel(sm);
sm->select(completer->completionModel()->index(0,0), QItemSelectionModel::Select);
Probably the change of the selection for the popup (its a view) ocurs when selectionChanged() is emited.
So you have to set first the selection model, then do the select.
void QItemSelectionModel::select ( const QModelIndex & index,
QItemSelectionModel::SelectionFlags command ) [virtual slot]
Selects the model item index using the specified command, and emits
selectionChanged().
BTW, u dont have to create a new selection model, just ask the popup for it (Againt, its a view):
completer->popup()->selectionModel();
http://qt-project.org/doc/qt-5.0/qtwidgets/qabstractitemview.html#selectionModel
I don't know if this is what you wanted, but in my case I wanted to be able to press enter and auto-select the first item in the pop-up list (as it does with UnfilteredPopupCompletion).
What worked for me was:
class AutoSelectFirstFilter : public QObject
{
Q_OBJECT
protected:
virtual bool eventFilter(QObject *obj, QEvent *event) override
{
if (event->type() == QEvent::KeyPress)
{
if(static_cast<QKeyEvent *>(event)->key() == Qt::Key_Return)
{
QAbstractItemView* l = static_cast<QAbstractItemView*>(obj);
QModelIndex i = l->model()->index(0,0);
if(i.isValid())
l->selectionModel()->select(i, QItemSelectionModel::Select);
}
}
return false;
}
};
and than:
AutoSelectFirstFilter tmp;
completer->popup()->installEventFilter(&tmp);
PS: Don't forget to re-run qmake.
Related
I'm making a program where the user can add multiple people (participants) in a list. When the "Add" button is clicked, a new row is added and "edit" is called for the name field. All is well so far, but there is a thing I'd like to implement, and I can't seem to figure out how: when the user closes the editing field (presses enter or escape, clicks elsewhere, etc.) and if the name field remains empty, I'd like the row to be deleted. In other words, a name has to be filled in. Here is what I have so far:
void MainWindow::addParticipant()
{
QList<QStandardItem *> newRow;
newRow << new QStandardItem()
<< new QStandardItem();
participantModel->appendRow(newRow);
participantView->edit(participantModel->index(participantModel->rowCount()-1, 0));
}
Here participantModel is a QStandardItemModel and participantView is a QTreeView. I tried using signals and slots to detect when a row is empty and to delete it, but it hasn't worked and the syntax is elusive to me.
Ideally I'd be able to detect when the name field is not being edited anymore, so that I can delete the row if need be.
Here is ugly but working solution: subclass from QItemDelegate and check input data inside setModelData member function. As far setModelData has a const qualifier you can not modify model inside it, so you need some trick: in the following example the model is modified inside handler of closeEditor signal.
class MainWidget : public QWidget
{
Q_OBJECT
public:
MainWidget ()
{
QStandardItemModel * model = new QStandardItemModel ();
ItemDelegate * delegate = new ItemDelegate ();
table->setItemDelegate (delegate);
connect (delegate, & ItemDelegate::closeEditor, [=](){
if (isEmpty) {
model->removeRow (emptyRow);
isEmpty = false;
emptyRow = -1;
}
});
connect (delegate, & ItemDelegate::cellEdited, [=](const int row){
isEmpty = true;
emptyRow = row;
});
}
bool isEmpty;
int emptyRow;
};
class ItemDelegate : public QItemDelegate
{
Q_OBJECT
signals:
void cellEdited (int) const;
public:
void setModelData (QWidget * widget, QAbstractItemModel * model, const QModelIndex & index) const override
{
if (0 == index.column () ) {
if (QLineEdit * cellWidget = qobject_cast <QLineEdit *> (widget) ) {
if (cellWidget->text ().isEmpty () ) {
emit cellEdited (index.row () );
return;
}
}
}
QItemDelegate::setModelData (widget, model, index);
}
};
Complete example available at GitLab.
The comments/answers posted thus far have urged me to look more into item delegates. Quite embarrassingly, after relatively little googling I found the following solution for my problem:
void MainWindow::addParticipant()
{
QStyledItemDelegate *participantDelegate = new QStyledItemDelegate;
participantView->setItemDelegateForColumn(0, participantDelegate);
QList<QStandardItem *> newRow;
newRow << new QStandardItem()
<< new QStandardItem();
participantModel->appendRow(newRow);
connect(participantDelegate, SIGNAL(closeEditor(QWidget*,QAbstractItemDelegate::EndEditHint)), this, SLOT(checkRow()));
participantView->edit(participantModel->index(participantModel->rowCount()-1, 0));
}
Apparently the closeEditor signal (only available to delegates) is exactly what I was looking for. When the editor is closed, the slot checkRow() checks if the name field of the participant is empty and decides whether or not to delete the row.
I've subclassed the QGroupBox class, with the checkable property enabled. I'm trying to override the behaviour of the toggle/checked events.
Here's the code:
class SideWidgetGroupBox: public QGroupBox
{
Q_OBJECT
public:
SideWidgetGroupBox(QWidget* parent = 0): QGroupBox(parent)
{
this->setCheckable(true);
connect(this, SIGNAL(toggled(bool)), this, SLOT(my_toggled(bool)));
}
private slots:
void my_toggled (bool on)
{
std::cout << "my toggled method" <<std::endl;
}
};
So far so good, my slot gets executed. However the groupboxs' contents also get enabled/disabled. Is there a way to prevent that? Or do I have to manually reset the original enabled/disabled state?
Is there a way to prevent enabling/disabling of a content?
Yes, but this way is not easy, because there is no QCheckBox there. What looks like a check box is an area of QGroupBox. And all events are processed by QGroupBox:
1. Override event method and prevent processing of QEvent::KeyRelease and QEvent::MouseRelease events by the base class.
bool SideWidgetGroupBox::event(QEvent *e)
{
switch (e->type()) {
case QEvent::KeyRelease:
case QEvent::MouseButtonRelease:
myHandler(e);
return true;
}
return QGroupBox::event(e);
}
2. In myHandler check whether space pressed or the mouse clicked on the checkbox. Store checkBox value and do what you need. Use this code to check what is under cursor:
QStyleOptionGroupBox box;
initStyleOption(&box);
QStyle::SubControl released = style()->hitTestComplexControl(QStyle::CC_GroupBox, &box,
event->pos(), this);
bool toggle = released == QStyle::SC_GroupBoxLabel || released == QStyle::SC_GroupBoxCheckBox;
if (toggle)
{
m_state = !m_state;
update();
}
3. Add method initStyleOption and set state to the state of the checkBox (you should store it by yourself):
void SideWidgetGroupBox::initStyleOption(QStyleOptionGroupBox *option) const
{
QGroupBox::initStyleOption(option);
QStyle::State flagToSet = m_state ? QStyle::State_On : QStyle::State_Off;
QStyle::State flagToRemove = m_state ? QStyle::State_Off : QStyle::State_On;
option->state |= flagToSet;
option->state &= ~flagToRemove;
option->state &= ~QStyle::State_Sunken;
}
4.Method initStyleOption in QGroupBox is not virtual that is why you need to reimplement paintEvent also:
void paintEvent(QPaintEvent *)
{
QStylePainter paint(this);
QStyleOptionGroupBox option;
initStyleOption(&option);
paint.drawComplexControl(QStyle::CC_GroupBox, option);
}
do I have to manually reset the original enabled/disabled state?
You can't do this with setEnabled because it checks current checked state and prevents enabling of children. Although you can call setEnabled for children directly using this->findChildren<QWidget*>
Suggestion
You can use ways described above or remove standard checkBox and(or) label and put your own QCheckBox over the group (without layout, of course) and use it as you want. If you group can be moved you will need to move the check box also.
Is there any way to check that the ui elements(line edit,combo box,etc.) of the dialog has been changed.
What I want is to show a message to the user if he changes the value of any single ui element, saying that details have been partially filled.
What i can do is use connect for each ui element & based on the value changed of each element i am setting a boolean flag & at the time of close event i am checking that boolean flag.
But Its quite complicate to check it for each widget.
Is there any easier way.
Code that I am using for single ui element is,
connect(ui->leAge,SIGNAL(textChanged(QString)),this,SLOT(functChanged())); //In Constructor
void DemoDialog::functChanged() //Will be called if value of line edit (ui->leAge) is changed
{
flag=true;
}
void DemoDialog::closeEvent(QCloseEvent *event)
{
if (flag) {
if (QMessageBox::warning(this,"Close","Do you want to close?",QMessageBox::Yes|QMessageBox::No)==QMessageBox::Yes) {
this->close();
}
}
You can't reimplement closeEvent to prevent closing a window. The close() call that you do is either redundant or an error (infinite recursion), since a closeEvent method call is just a way of being notified that a closing is imminent. At that point it's too late to do anything about it.
Keep in mind the following:
Closing a dialog usually is equivalent to canceling the dialog. Only clicking OK should accept the changes.
When a user wants to close a dialog, you don't have to ask them about it. They initiated the action. But:
It is proper to ask a user about dialog closure if there are changes have not been accepted - on platforms other than OS X.
So, you have to do several things:
Reimplement the void event(QEvent*) method. This allows you to reject the close event.
Offer Apply/Reset/Cancel buttons.
Your flag approach can be automated. You can find all the controls of the dialog box and set the connections automatically. Repeat the statement below for every type of control - this gets tedious rather quickly:
foreach(QTextEdit* w, findChildren<QTextEdit*>())
connect(w, SIGNAL(textChanged(QString)), SLOT(functChanged()));
You can leverage the meta property system. Most controls have a user property - that's the property that holds the primary value of the control (like text, selected item, etc). You can scan all of the widget children, and connect the property change notification signal of the user property to your flag:
QMetaMethod slot = metaObject().method(
metaObject().indexOfSlot("functChanged()"));
foreach (QWidget* w, findChildren<QWidget*>()) {
QMetaObject mo = w->metaObject();
if (!mo.userProperty().isValid() || !mo.userProperty().hasNotifySignal())
continue;
connect(w, mo.notifySignal(), this, slot);
}
Each widget is a QObject. QObjects can have properties, and one of the properties can be declared to be the user property. Most editable widget controls have such a property, and it denotes the user input (text, numerical value, selected index of the item, etc.). Usually such properties also have change notification signals. So all you do is get the QMetaMethod denoting the notification signal, and connect it to your function that sets the flag.
To determine the changed fields, you don't necessarily need a flag. In many dialog boxes, it makes sense to have a data structure that represent the data in the dialog. You can then have a get and set method that retrieves the data from the dialog, or sets it on the dialog. To check for changed data, simply compare the original data to current data:
struct UserData {
QString name;
int age;
UserData(const QString & name_, int age_) :
name(name_), age(age_) {}
UserData() {}
};
class DialogBase : public QDialog {
QDialogButtonBox m_box;
protected:
QDialogButtonBox & buttonBox() { return m_box; }
virtual void isAccepted() {}
virtual void isApplied() {}
virtual void isReset() {}
virtual void isRejected() {}
public:
DialogBase(QWidget * parent = 0) : QDialog(parent) {
m_box.addButton(QDialogButtonBox::Apply);
m_box.addButton(QDialogButtonBox::Reset);
m_box.addButton(QDialogButtonBox::Cancel);
m_box.addButton(QDialogButtonBox::Ok);
connect(&m_box, SIGNAL(accepted()), SLOT(accept()));
connect(&m_box, SIGNAL(rejected()), SLOT(reject()));
connect(this, &QDialog::accepted, []{ isAccepted(); });
connect(this, &QDialog::rejected, []{ isRejected(); });
connect(&buttonBox(), &QDialogButtonBox::clicked, [this](QAbstractButton* btn){
if (m_box.buttonRole(btn) == QDialogButtonBox::ApplyRole)
isApplied();
else if (m_box.buttonRole(btn) == QDialogButtonBox::ResetRole)
isReset();
});
}
}
class UserDialog : public DialogBase {
QFormLayout m_layout;
QLineEdit m_name;
QSpinBox m_age;
UserData m_initialData;
public:
UserDialog(QWidget * parent = 0) : QDialog(parent), m_layout(this) {
m_layout.addRow("Name", &m_name);
m_layout.addRow("Age", &m_age);
m_age.setRange(0, 200);
m_layout.addRow(&buttonBox());
}
/// Used by external objects to be notified that the settings
/// have changed and should be immediately put in effect.
/// This signal is emitted when the data was changed.
Q_SIGNAL void applied(UserData const &);
UserData get() const {
return UserData(
m_name.text(), m_age.value());
}
void set(const UserData & data) {
m_name.setText(data.name);
m_age.setValue(data.age);
}
void setInitial(const UserData & data) { m_initialData = data; }
bool isModified() const { return get() == m_initialData; }
protected:
void isAccepted() Q_DECL_OVERRIDE { emit applied(get()); }
void isApplied() Q_DECL_OVERRIDE { emit applied(get()); }
void isReset() Q_DECL_OVERRIDE { set(m_initialData); }
};
If you're only checking whether the input fields are filled when the Dialog closes, you don't need the flags you can only check if there is any input.
If you are filling the input fields programatically at some points but are also only interested in the change when the dialog closes, you can also check in the close function whether the current input is equal to the one you set earlier.
From the code you posted, I can't really see what you need the flags for.
How to make a QT dialog read-only? Any general way to implement it easily? For example
(1) set all its containing widgets disable. (how to implement it?)
(2) Intercept edit events like key pressed, mouse pressed but how not to intercept the one to close the dialog?
I think this feature should be very helpful.
Disabling the widgets can be done similar to the following:
void myDialog::disableWidgets()
{
QList<QWidget *> widgets = this->findChildren<QWidget *>();
foreach(QWidget* widget, widgets)
{
widget->setEnabled(false);
}
}
To intercept events, QDialog includes the function installEventFilter(QObject*).
This allows you to use a separate object to receive all events passed to the dialog. You can then choose to handle the event in the object, or pass it on to the dialog itself by calling the base class QObject::eventFilter
class MyEventHandler : public QObject
{
Q_OBJECT
protected:
bool MyEventHandler::eventFilter(QObject *obj, QEvent *event)
{
// handle key press events
if (event->type() == QEvent::KeyPress)
{
// Do something
// ...
return true; // event handled by the class
}
else
{ // ignore this event and pass it to the dialog as usual
return QObject::eventFilter(obj, event);
}
}
return false;
};
QDialog* dlg = new QDialog;
MyEventHandler evtHandler = new MyEventHandler;
dlg->installEventFilter(evtHandler);
Read-only is a strange term to apply to a dialog. Disabling all widgets as above does the trick. If you only wanted to make the input part of a QInputDialog read-only (while leaving scrollbars, buttons, etc. enabled), you could adapt that code as below:
QInputDialog dialog(this);
dialog.setOptions(QInputDialog::UsePlainTextEditForTextInput);
dialog.setWindowTitle("Title");
dialog.setLabelText("Label");
dialog.setTextValue("1\n2\n3\n");
QList<QWidget *> widgets = dialog.findChildren<QWidget *>();
foreach(QWidget* widget, widgets) {
if (strcmp(widget->metaObject()->className(),"QPlainTextEdit")==0) {
QPlainTextEdit *t = static_cast<QPlainTextEdit*>(widget);
t->setReadOnly(true);
}
}
dialog.exec();
I have a Qt combo box. When it pops, items are listed down. When right clicking an item, I hope a context menu to pop up. Any way to implement it? I find a function onContextMenuEvent under QComboBox. Does it help? Thanks.
You can obtain the list widget using QComboBox::view. You can add a context menu to the list as usual. But also you should install event filter on the view's viewport and block right click events because such events cause popup list to close.
In the initialization:
QAbstractItemView* view = ui->comboBox->view();
view->viewport()->installEventFilter(this);
view->setContextMenuPolicy(Qt::CustomContextMenu);
connect(view, SIGNAL(customContextMenuRequested(QPoint)),
this, SLOT(list_context_menu(QPoint)));
Event filter:
bool MainWindow::eventFilter(QObject *o, QEvent *e) {
if (e->type() == QEvent::MouseButtonRelease) {
if (static_cast<QMouseEvent*>(e)->button() == Qt::RightButton) {
return true;
}
}
return false;
}
In the slot:
void MainWindow::list_context_menu(QPoint pos) {
QAbstractItemView* view = ui->comboBox->view();
QModelIndex index = view->indexAt(pos);
if (!index.isValid()) { return; }
QMenu menu;
QString item = ui->comboBox->model()->data(index, Qt::DisplayRole).toString();
menu.addAction(QString("test menu for item: %1").arg(item));
menu.exec(view->mapToGlobal(pos));
}
In this example items are identified by their displayed texts. But you also can attach additional data to items using QComboBox::setItemData. You can retrieve this data using ui->comboBox->model()->data(...) with the role that was used in setItemData.