I am having trouble accessing a QTextEdit from a main window in another form. Please help.
void properties::on_okWordPushButton_clicked()
{
if (ui->wordcombo->currentText() == "All Words") {
int wordCount = notepad->textEdit->toPlainText().split(QRegExp("(\\s|\\n|\\r)+"), QString::SkipEmptyParts).count();
ui->wordcountlabel->setText(QString::number(wordCount));
}
}
I am getting an error since I cannot read notepad->textEdit
You can use at least 2 possibilities:
Dirty way:
On form creation, pass pointer to your QTextEdit:
// mainwindow.cpp
auto myProperties = new properties(notepad->textEdit);
...
// properties.h
QTextEdit *outerEditor;
// properties.cpp
properties::properties(QTextEdit *editor) {
outerEditor = editor;
...
}
Then, on your slot you can use:
int wordCount = editor->toPlainText().split(QRegExp("(\\s|\\n|\\r)+"), QString::SkipEmptyParts).count();
Qt-way:
Remember - signals/slots are awesome.
Just after form creation, you can connect signal from MainWindow to properties passing text in your QTextEdit and store it locally:
// MainWindow.cpp
auto myProperties = new properties(notepad->textEdit);
connect(this->textEdit, QOverload<QString>::of(&QTextEdit::valueChanged), myProperties, GetNewValue);
// properties.h
void GetNewValue(QString val);
// properties.cpp
void properties::GetNewValue(QString val) {
ui->wordcountlabel->setText(QString::number(val.toPlainText().split(QRegExp("(\\s|\\n|\\r)+"), QString::SkipEmptyParts).count());
}
You can't do this, the ui is a private member of a widget, create a function that returns or sets what you need!
Related
I am trying to create a configuration menu box for an application, and have used a QDialog box to display the options that the user can change. This box contains QComboBoxes and QLineEdits, but a lot of them (7 combo boxes and 12 line edits). There is a QPushButton in the bottom called "Apply Changes" that should get enabled only when any property in the box gets changed.
Do I have to link every signal from each widget with a slot to enable the button individually or is there a signal that the QDialog box itself emits when there is a change in its constituent widgets?
Right now I have this:
connect(Combo1,SIGNAL(activated(QString)),this,SLOT(fnEnable(QString)));
connect(Combo2,SIGNAL(activated(QString)),this,SLOT(fnEnable(QString)))
followed by 17 more lines of these connections.
void MyClass::fnEnable(QString)
{
ApplyButton->setEnabled(true); //It is initialised as false
}
I was wondering if there was a shorter way of doing this, maybe (like I mentioned before) a signal emitted by QDialog (I couldn't find one in the documentation)
I know that this does not speed up the program, as only the required connection is called, but it would make any further attempts at making more ambitious dialog boxes easier.
Actually there is no such signal, but one approach is to create a list of QComboBox, and make the connections with a for, for example:
QList <*QCombobox> l;
l<<combobox1<< combobox2<< ....;
for (auto combo: l) {
connect(combo, &QComboBox::activated, this, &MyClass::fnEnable);
}
The same would be done with QLineEdit.
You can iterate over an initializer list of widgets boxes and leverage C++11 to do all the boring work for you:
MyClass::MyClass(QWidget * parent) : QWidget(parent) {
auto const comboBoxes = {Combo1, Combo2, ... };
for (auto combo : comboBoxes)
connect(combo, &QComboBox::activates, this, &MyClass::fnEnable);
}
You can also automatically find all the combo boxes:
MyClass::MyClass(QWidget * parent) : QWidget(parent) {
ui.setupUi(this); // or other setup code
for (auto combo : findChildren<QComboBox*>(this))
connect(combo, &QComboBox::activated, this, &MyClass::fnEnable);
}
Or you can automatically attach to the user property's change signal. This will work on all controls that have the user property. The user property is the property of a control that contains the primary data the control is displaying.
void for_layout_widgets(QLayout * layout, const std::function<void(QWidget*)> & fun,
const std::function<bool(QWidget*)> & pred = +[](QWidget*){ return true; })
{
if (!layout) return;
for (int i = 0; i < layout->count(); ++i) {
auto item = layout->itemAt(i);
for_layout_widgets(item->layout(), fun, pred);
auto widget = item->widget();
if (widget && pred(widget)) fun(widget);
}
}
class MyClass : public QWidget {
Q_OBJECT
Q_SLOT void MyClass::fnEnable(); // must take no arguments
...
};
MyClass::MyClass(QWidget * parent) : QWidget(parent) {
// setup code here
auto slot = metaObject()->method(metaObject()->indexOfMethod("fnEnable()"));
Q_ASSERT(slot.isValid());
for_layout_widgets(layout(), [=](QWidget * widget){
auto mo = widget->metaObject();
auto user = mo->userProperty();
if (!user.isValid()) return;
auto notify = user.notifySignal();
if (!notify.isValid()) return;
connect(widget, notify, this, slot);
});
}
You can also keep the combo boxes in an array, by value. This minimizes the costs of indirect references and results in code that will take the least amount of memory possible and perform well:
class MyClass : public QWidget {
Q_OBJECT
QVBoxLayout m_layout{this};
std::array<QComboBox, 14> m_comboBoxes;
...
};
MyClass(QWidget * parent) : QWidget(parent) {
for (auto & combo : m_comboBoxes) {
m_layout.addWidget(&combo);
connect(&combo, &QComboBox::activates, this, &MyClass::fnEnable);
}
}
In my programm, I fill my interface with a lot of checkbox by this way :
void VGCCC::addMaterialToUI(QDomNodeList _materialNodeList, QWidget* _areaWidget, QLayout* _layout, QWidget* _layoutWidget, int _maTable)
{
for(int i=0; i< _materialNodeList.count();i++)
{
QDomElement materialElement = _materialNodeList.at(i).toElement();
QString elementFile = materialElement.attribute("file");
QString elementId = materialElement.attribute("id");
QString elementLabel = elementId;
elementLabel += " - ";
elementLabel += materialElement.attribute("label");
QCheckBox* checkbox = new QCheckBox(elementLabel);
_layout->addWidget(checkbox);
_layoutWidget->adjustSize();
_areaWidget->setMinimumHeight(_layoutWidget->height());
_areaWidget->setMinimumWidth(_layoutWidget->width());
configuration c;
c.path = (m_igmPath+elementFile).toStdString();
c.id = elementId.toInt();
c.name = elementLabel.toStdString();
if(_maTable==0)
{
m_materialSectionMap[checkbox] = c;
}
else
{
m_materialPostMap[checkbox] = c;
}
}
}
I would like to know how to retrieve these "abstract" checkbox. More exactly, if one of these checkbox is checked, I would like to call another function like this :
connect(anyCheckbox,SIGNAL(stateChanged(anyCheckbox)), this, SLOT(doSomethingFunctionIfCheckboxIsChecked()));
The difficulty is that in my UI, these checkbox didn't exist, so I can't connect them to my function. How can I solve it ?
You can e.g. collect pointers to your checkbox objects to a list so can access or "retrieve" them later.
You can connect each checkbox's stateChanged signal to a same slot which is then called when state of any of the checkboxes is changed. In the slot you can cast the sender() to a checkbox if you need to know which specific checkbox is in question. Another alternative is to use QSignalMapper.
In your class declaration:
private slots:
void checkboxStateChanged(int state)
private:
QList<QCheckBox*> m_checkboxes;
In your class definition:
void VGCCC::addMaterialToUI(QDomNodeList _materialNodeList, QWidget* _areaWidget, QLayout* _layout, QWidget* _layoutWidget, int _maTable)
{
...
QCheckBox* checkbox = new QCheckBox(elementLabel);
m_checkboxes.append(checkbox);
connect(checkbox, SIGNAL(stateChanged(int)), this, SLOT(checkboxStateChanged(int)));
...
}
void VGCCC::checkboxStateChanged(int state)
{
// Here your can e.g. call doSomethingFunctionIfCheckboxIsChecked()
QCheckBox* checkbox = qobject_cast<QCheckBox*>(sender());
if (checkbox)
{
// checkbox points to the object whose state changed
}
}
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.
In our application that uses Qt 4 and supports touch input, we use the QFileDialog with the options QFileDialog::DontUseNativeDialog and QFileDialog::ExistingFiles.
The first is needed because we set our own stylesheet and that does not work with the native dialog. The second is for needed for selecting multiple files, which is what we want to do.
The problem ist that one can not select multiple files with touch input in the QFileDialog, because we have no "shift" or "ctrl"-key available. In Windows the problem is solved by adding checkboxes to the items. QFileDialog has no checkboxes.
I tried to manipulate the QFileDialog to make it displays check boxes for the items, but I failed.
I tried to exchanged the QFileSystemModel that is used by the underlying QTreeView and QListView, but this breaks the signal-slot connections between the model and the dialog. I could not find a way to restore them because they are burried deep in the private intestants of the dialog.
At this moment the only solution I can imagine is writing a whole new dialog, but I would like to avoid the effort.
So is there a way to add checkboxes to the QFileDialog model views ?
Do you have another idea how selecting multiple files could be made possible?
Is the problem fixed in Qt 5? We want to update anyway.
Thank you for your Help.
As I failed to add checkboxes to the item views, I implemented a "hacky" work-around. It adds an extra checkable button to the dialog that acts as a "ctrl"-key. When the button is checked, multiple files can be selected. The solution is a little bit ugly, because it relies on knowing the internals of the dialog, but it does the job.
So here is the code for the header ...
// file touchfiledialog.h
/*
Event filter that is used to add a shift modifier to left mouse button events.
This is used as a helper class for the TouchFileDialog
*/
class EventFilterCtrlModifier : public QObject
{
Q_OBJECT;
bool addCtrlModifier;
public:
EventFilterCtrlModifier( QObject* parent);
void setAddCtrlModifier(bool b);
protected:
virtual bool eventFilter( QObject* watched, QEvent* e);
};
/*
TouchDialog adds the possibility to select multiple files with touch input to the QFileDialog.
This is done by adding an extra button which can be used as control key replacement.
*/
class QTOOLS_API TouchFileDialog : public QFileDialog
{
Q_OBJECT
EventFilterCtrlModifier* listViewEventFilter;
EventFilterCtrlModifier* treeViewEventFilter;
bool initialized;
public:
TouchFileDialog( QWidget* parent);
protected:
virtual void showEvent( QShowEvent* e);
private slots:
void activateCtrlModifier(bool b);
private:
void initObjectsForMultipleFileSelection();
};
with the implementation ...
// file touchfiledialog.cpp
#include "touchfiledialog.h"
EventFilterCtrlModifier::EventFilterCtrlModifier(QObject* parent)
: QObject(parent)
, addCtrlModifier(false)
{
}
void EventFilterCtrlModifier::setAddCtrlModifier(bool b)
{
addCtrlModifier = b;
}
bool EventFilterCtrlModifier::eventFilter(QObject* watched, QEvent* e)
{
QEvent::Type type = e->type();
if( type == QEvent::MouseButtonPress || type == QEvent::MouseButtonRelease)
{
if( addCtrlModifier)
{
QMouseEvent* mouseEvent = static_cast<QMouseEvent*>(e);
// Create and post a new event with ctrl modifier if the event does not already have one.
if( !mouseEvent->modifiers().testFlag(Qt::ControlModifier))
{
QMouseEvent* newEventWithModifier = new QMouseEvent(
type,
mouseEvent->pos(),
mouseEvent->globalPos(),
mouseEvent->button(),
mouseEvent->buttons(),
mouseEvent->modifiers() | Qt::ControlModifier
);
QCoreApplication::postEvent(watched, newEventWithModifier);
return true; // absorb the original event
}
}
}
return false;
}
//#######################################################################################
TouchFileDialog::TouchFileDialog(QWidget* parent)
: QFileDialog(parent)
, listViewEventFilter(NULL)
, treeViewEventFilter(NULL)
, initialized(false)
{
}
void TouchFileDialog::showEvent(QShowEvent* e)
{
// install objects that are needed for multiple file selection if needed
if( !initialized)
{
if( fileMode() == QFileDialog::ExistingFiles)
{
initObjectsForMultipleFileSelection();
}
initialized = true;
}
QFileDialog::showEvent(e);
}
void TouchFileDialog::initObjectsForMultipleFileSelection()
{
// install event filter to item views that are used to add ctrl modifiers to mouse events
listViewEventFilter = new EventFilterCtrlModifier(this);
QListView* listView = findChild<QListView*>();
listView->viewport()->installEventFilter(listViewEventFilter);
treeViewEventFilter = new EventFilterCtrlModifier(this);
QTreeView* treeView = findChild<QTreeView*>();
treeView->viewport()->installEventFilter(treeViewEventFilter);
QGridLayout* dialogLayout = static_cast<QGridLayout*>(layout()); // Ugly because it makes assumptions about the internals of the QFileDialog
QPushButton* pushButtonSelectMultiple = new QPushButton(this);
pushButtonSelectMultiple->setText(tr("Select multiple"));
pushButtonSelectMultiple->setCheckable(true);
connect( pushButtonSelectMultiple, SIGNAL(toggled(bool)), this, SLOT(activateCtrlModifier(bool)));
dialogLayout->addWidget(pushButtonSelectMultiple, 2, 0);
}
void ZFFileDialog::activateCtrlModifier(bool b)
{
listViewEventFilter->setAddCtrlModifier(b);
treeViewEventFilter->setAddCtrlModifier(b);
}
The TouchFileDialog installs an event filter to the item views that will add a ControlModifier to the mouse events of the views when the corresponging button in the dialog is checked.
Feel free to post other solutions, because this is somewhat improvised.
I am trying to create pop-up menu depending on a variable as follows:
QMenu menu(widget);
for(int i = 1; i <= kmean.getK(); i++)
{
stringstream ss;
ss << i;
string str = ss.str();
string i_str = "Merge with " + str;
QString i_Qstr = QString::fromStdString(i_str);
menu.addAction(i_Qstr, this, SLOT(mergeWith1()));
}
menu.exec(position);
where:
kmean.get(K) returns an int value,
mergeWith1() is some `SLOT()` which works fine
Issue:
The loop creates an action on menu only for i=1 case, and ignores other values of i.
Additional information
When doing the same loop with casual int values (without convert) everything works fine. e.g. if I do in loop only menu.addAction(i, this, SLOT(...))) and my K=4, a menu will be created with four actions in it, named 1, 2, 3, 4 correspondingly.
What can be the problem caused by
I think the issue is in convert part, when I convert i to string using stringstream and after to QString. May be the value is somehow lost. I am not sure.
QESTION:
How to make the loop accept the convert part?
What do I do wrong in convert part?
In Qt code, you shouldn't be using std::stringstream or std::string. It's pointless.
You have a crashing bug by having the menu on the stack and giving it a parent. It'll be double-destructed.
Don't use the synchronous blocking methods like exec(). Show the menu asynchronously using popup().
In order to react to the actions, connect a slot to the menu's triggered(QAction*) signal. That way you can deal with arbitrary number of automatically generated actions.
You can use the Qt property system to mark actions with custom attributes. QAction is a QObject after all, with all the benefits. For example, you can store your index in an "index" property. It's a dynamic property, created on the fly.
Here's a complete example of how to do it.
main.cpp
#include <QApplication>
#include <QAction>
#include <QMenu>
#include <QDebug>
#include <QPushButton>
struct KMean {
int getK() const { return 3; }
};
class Widget : public QPushButton
{
Q_OBJECT
KMean kmean;
Q_SLOT void triggered(QAction* an) {
const QVariant index(an->property("index"));
if (!index.isValid()) return;
const int i = index.toInt();
setText(QString("Clicked %1").arg(i));
}
Q_SLOT void on_clicked() {
QMenu * menu = new QMenu();
int last = kmean.getK();
for(int i = 1; i <= last; i++)
{
QAction * action = new QAction(QString("Merge with %1").arg(i), menu);
action->setProperty("index", i);
menu->addAction(action);
}
connect(menu, SIGNAL(triggered(QAction*)), SLOT(triggered(QAction*)));
menu->popup(mapToGlobal(rect().bottomRight()));
}
public:
Widget(QWidget *parent = 0) : QPushButton("Show Menu ...", parent) {
connect(this, SIGNAL(clicked()), SLOT(on_clicked()));
}
};
int main (int argc, char **argv)
{
QApplication app(argc, argv);
Widget w;
w.show();
return app.exec();
}
#include "main.moc"