I have a numeric editor that extends the QSpinBox
NumericEditor::NumericEditor(QWidget *widget): QSpinBox(widget)
I use this editor to edit the type QVariant::Int in the QTableWidget
QItemEditorCreatorBase *numericEditor = new QStandardItemEditorCreator<NumericEditor>();
factory->registerEditor(QVariant::Int, numericEditor);
Data is entered in the table as normal. Ignore the usage of the word "color". Its based off the color editor example.
QTableWidgetItem *nameItem2 = new QTableWidgetItem(QString("label2"));
QTableWidgetItem *colorItem2 = new QTableWidgetItem();
colorItem2->setData(Qt::DisplayRole, QVariant(int(4)));
table->setItem(1, 0, nameItem2);
table->setItem(1, 1, colorItem2);
The spin box appears and works fine in the QTableWidget.
My desire is to get access to the instance of QSpinBox that the table uses when it edits QVariant::Int cells so I can set the min and max values.
How can I do this?
You can install a delegate on the column with QTableWidget::setItemDelegateForColumn, and when an editor is opened, its createEditor method will be called.
class MyDelegate : public QStyledItemDelegate {
public:
QWidget *createEditor ( QWidget * parent, const QStyleOptionViewItem & option, const QModelIndex & index ) const {
// You could create the widget from scratch or call
// the base function which will use the QItemEditor you already wrote
QWidget * editor = QStyledItemDelegate::createEditor(parent, option, index);
// do whatever you need to do with the widget
editor->setProperty("minimum", 100);
editor->setProperty("maximum", 100);
return editor;
}
};
Related
I have a QTableWidget and for all rows I set a setCellWidget at one column to a button.
I would like to connect this button to a function that delets this row.
I tried this code, which does not work, because if I simply click my button I do not set the current row to the row of the button.
ui->tableWidget->insertRow(ui->tableWidget->rowCount());
QPushButton *b = new QPushButton("delete",this);
ui->tableWidget->setCellWidget(ui->tableWidget->rowCount()-1,0,b);
connect(d,SIGNAL(clicked(bool)),this,SLOT(deleteThisLine()));
...
void MainWindow::deleteThisLine()
{
int row = ui->tableWidget->currentRow();
ui->tableWidget->removeRow(row);
}
How can I connect my button to a function in a way that the function knows which button (at which row) was pressed?
To remove the row we must first get the row, if we are inserting widgets inside the cells the currentRow() method will not return the appropriate row, in many cases it will return the row of the last cell without widget that has been selected.
For that reason you must opt for another solution, for this case we will use the indexAt() method of QTableWidget, but for this we need to know the position in pixels of the cell. when one adds a widget to a cell, this cell will be the parent of the widget, so we can access from the button to the cell using the parent() method, and then get the position of the cell with respect to the QTableWidget and use it in indexAt(). To access the button we will use the sender().
When the current cell is removed the focus is lost, a possible solution is to place the focus again in another cell.
void MainWindow::deleteThisLine()
{
//sender(): QPushButton
QWidget *w = qobject_cast<QWidget *>(sender()->parent());
if(w){
int row = ui->tableWidget->indexAt(w->pos()).row();
ui->tableWidget->removeRow(row);
ui->tableWidget->setCurrentCell(0, 0);
}
}
Use this connection way to connect signal to a slot:
connect(ui->btnDelete, &QPushButton::clicked, this,&MainWindow::deleteRow);
And delete for example a row on call function:
void MainWindow::deleteRow()
{
int row = ui->tableWidget->currentRow();
ui->tableWidget->removeRow(row);
}
Create a custom class, where you pass the created push button object and the row index. From your custom push button class, handle the push button press event and emit a custom signal (it will carry the index number) handled from the object where your custom pushbutton is created. Some related code are below, to give you a hint:
.h
class mypushbutton {
explicit mypushbutton(QObject *parent = 0, QPushButton *pushbutton = 0, int index = 0);
signal:
void deleteRow(int index);
}
.cpp
mypushbutton() {
connect(pushbutton, SIGNAL(clicked(bool)), this, SLOT(actionButtonClick(bool)));
}
actionbuttonclicked() { emit deleteRow(index);}
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);
}
}
I have a GUI project in Qt Creator that functions as a shopping list. I am using a QLineEdit to add items to a QTableWidget. The user types something in, presses the QPushButton. The slot then adds a new row to the QTableWidget with the input, in the first column, and a new QPushButton in the second column. I then want the user to be able to press the button and have it clear that row, but I don't know how to access that slot, or sender (I'm not sure the proper term.) Here is the code so far. itemList is my QTableWidget, itemInput is the QLineEdit.
void MainWindow::on_btnAddItem_clicked()
{
ui->itemList->insertRow(ui->itemList->rowCount());
ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
QPushButton *clear = new QPushButton("Clear",this);
ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
ui->itemInput->clear();
}
Here is when the program is initially run. Once they click the button, it runs on_btnAddItem_clicked()
Then it looks like this, and I want to make the clear button remove the row it is a part of.
Do I need to create a new slot? Any help?
You will need to make your own button class and inherit QPushButton. Something like this :
class MyButton : public QPushButton {
public:
MyButton();
QTableWidgetItem *titem;
}
And here you MainWindow :
void MainWindow::on_btnAddItem_clicked()
{
ui->itemList->insertRow(ui->itemList->rowCount());
ui->itemList->setItem((ui->itemList->rowCount())-1,0,new QTableWidgetItem(ui->itemInput->text()));
MyButton *clear = new MyButton("Clear",this);
clear->titem = ui->itemList->item(ui->itemList->rowCount()-1, 0);
connect(clear, SIGNAL(clicked()), SLOT(on_btnClear_Clicked()));
ui->itemList->setIndexWidget(ui->itemList->model()->index(ui->itemList->rowCount()-1, 1), clear);
ui->itemInput->clear();
}
void MainWindow::on_btnClear_Clicked()
{
MyButton *btn = (MyButton*)QObject::sender();
ui->itemList->removeRow(btn->titem->row());
}
Please note, it is only step to do it.
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 QListWidget in my MainWindow that displays a list of VideoWidgets (a custom QWidget).
VideoWidget has a clickable label where on clicking the label it should delete a file and then remove the QListItem which holds the VideoWidget from the QListWidget. Here is my VideoWidget class:
VideoWidget::VideoWidget(QWidget *parent) : QWidget(parent)
{
ClickableLabel *smallRed = new ClickableLabel(this)
//...
QObject::connect(smallRed,SIGNAL(clicked()),this,SLOT(removeVideo()));
}
void VideoWidget::removeVideo(){
//...code to remove a file
QListWidget* list = myParent->getList();
QListWidgetItem* item = list->takeItem(list->currentIndex().row());
myList->removeItemWidget(item);
}
The problem is that clicking the smallRed label will not select its item in the QListWidget which means that list->currentIndex().row() will return -1. Clicking anywhere else in the Widget does select the current item. For the code to work I currently have to first click anywhere in the VideoWidget and then click its ClickableLabel. Is there any way I can achieve the same effect with one single click on my ClickableLabel?
From your previous qestion, we suggested use signal and slots. For example:
for(int r=0;r<3;r++)
{
QListWidgetItem* lwi = new QListWidgetItem;
ui->listWidget->addItem(lwi);
QCheckBox *check = new QCheckBox(QString("checkBox%1").arg(r));
check->setObjectName("filepath");
connect(check,SIGNAL(clicked()),this,SLOT(echo()));
ui->listWidget->setItemWidget(lwi,check);
}
Slot:
void MainWindow::echo()
{
qDebug() << sender()->objectName() << "should be remmoved";
}
It is not unique way to solve this problem, but it shows all main things, with signals and slots mechanism, objectName and sender() you can achieve all what you need.
sender() return object which send signal, you can cast it, but if you need only objectName you should not cast.