I have a QTreeWidget where I insert different widgets (QDoubleSpinBox,QSpinBox,QCheckBox...)
QTreeWidget *t = ui->treeWidget;
QTreeWidgetItem *item = new QTreeWidgetItem();
int c = 0;
QDoubleSpinBox *dspb = new QDoubleSpinBox();
t->setItemWidget(item, c++, dspb);
QSpinBox *spb = new QSpinBox();
t->setItemWidget(item, c++, spb);
QCheckBox *cb = new QCheckBox();
t->setItemWidget(item, c++, cb);
t->addTopLevelItem(item);
However, the cb widget looks wired since the checkbox is aligned to the left. I would like to see it aligned in the center.
Q: How can I change the checkbox to appear in the middle of the TreeWidget cell?
I need to be able to access the cb item again later. Currently, I use the following code:
QTreeWidgetItem *itm = t->topLevelItem(0);
bool checked = qobject_cast<QCheckBox *>(t->itemWidget(itm,c++))->checkState() == Qt::Checked;
If I need to do some workaround to get the central alignment going, how can I access the cb object then?
Found it:
cb->setStyleSheet("margin-left:50%; margin-right:50%;");
works!
Related
I am using a QTreeWidget and setting a widget for the QTreeWidgetItem in the QTreeWidget. It is working fine but when I do the same for second time, the application is crashing.
The below is working fine.
QTreeWidget* treewidget = new QTreeWidget();
QTreeWidgetItem* item0 = new QTreeWidgetItem((QTreeWidget*)0, QStringList(QString("item0")));
treewidget->insertTopLevelItem(0,item0);
QSlider* slider0 = new QSlider();
treewidget->setItemWidget(item0, 0, slider0);
But if I add the last line once again, it is crashing when running the application.
The below is crashing.
QTreeWidget* treewidget = new QTreeWidget();
QTreeWidgetItem* item0 = new QTreeWidgetItem((QTreeWidget*)0, QStringList(QString("item0")));
treewidget->insertTopLevelItem(0,item0);
QSlider* slider0 = new QSlider();
treewidget->setItemWidget(item0, 0, slider0);
treewidget->setItemWidget(item0, 0, slider0); // Intentionally added to simulate the issue
The above is an example to show the issue, but in my application, based on some events, I delete the tree widget items and add it later. When I set the item widget (after adding the items later), I am getting the crash.
I could not figure out why. Any ideas? FYI, I am using Qt 5.3.2 MSVC 2010, 32 bit.
treewidget->setItemWidget(item0, 0, slider0);
treewidget->setItemWidget(item0, 0, slider0);// Intentionally added to simulate the issue
I look at Qt code (4.x):
void QTreeWidget::setItemWidget(QTreeWidgetItem *item, int column, QWidget *widget)
{
Q_D(QTreeWidget);
QAbstractItemView::setIndexWidget(d->index(item, column), widget);
}
and QAbstractItemView::setIndexWidget:
void QAbstractItemView::setIndexWidget(const QModelIndex &index, QWidget *widget)
{
Q_D(QAbstractItemView);
if (!d->isIndexValid(index))
return;
if (QWidget *oldWidget = indexWidget(index)) {
d->persistent.remove(oldWidget);
d->removeEditor(oldWidget);
oldWidget->deleteLater();
}
so if you add slider0 two times, then at first call it was added,
at seconds call Qt call for it deleteLater, and then added it,
are sure that this is what you want?
You have to set correct parent in the constructor of QTreeWidgetItem. Try this:
QTreeWidgetItem* item0 = new QTreeWidgetItem(treewidget);
Also it is important to understand who is owner of the slider0 after calling of setItemWidget(): the owner is your table, so 1) you don't need to delete this object; 2) the object will be deleted if you call setItemWidget for the same cell again. So, double call of treewidget->setItemWidget(item0, 0, slider0); seems very strange (second time you are setting the deleted object into that cell).
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.
I generate checkboxes as follows:
foreach(QString filt, types){
QCheckBox *checkbox = new QCheckBox(filt, this);
checkbox->setChecked(true);
vbox->addWidget(checkbox);
}
I need to get access to these checkboxes by name but they are all called the same?
I need to read the text they display.
How can I go about this?
Is it possible to run a for loop and attach the value of i onto the end of the checkbox. So in effect, the checkbox would be called checkbox[0], checkbox [1], etc?
EDIT:
I've changed the code to the following:
for(int i=0; i<types.count(); ++i)
{
QString filt = types[i];
*checkboxCount = *checkboxCount + 1;
QCheckBox *typecheckbox[i] = new QCheckBox(filt, this);
typecheckbox[i]->setChecked(true);
vbox->addWidget(typecheckbox[i]);
}
I thought this was a way to dynamically name the checkboxes so I can loop through them to get the text value from them.
I'm getting the error 'variable-sized object may not be initialized' on this line QCheckBox *typecheckbox[i] = new QCheckBox(filt, this);
Any ideas to a solution/ alternate approach?
If you want to access the checkboxes later, you can just use the find children method as follows:
QStringList myStringList;
QList<QCheckBox *> list = vbox->findChildren<QCheckBox *>();
foreach (QCheckBox *checkBox, list) {
if (checkBox->isChecked())
myStringList.append(checkBox->text());
}
After reading some examples I am still missing here something.
I have Qtreeview for view and QStandardItemModel for the data interface, also using QSortFilterProxyModel subclass but I don't know if its relevant.
This is my logic:
First I create the model with the QWidget as the parent:
QStandardItemModel m_model = new QStandardItemModel(0,4,parent);
then setSourceModel(m_model) for the widget
Set the treeview with QSortFilterProxyModel. something like this:
GroupProxyModel = new GroupSortFilterProxyModel;
GroupProxyModel->setDynamicSortFilter(true);
setSourceModel(createSubjectModel(parent));
ui.treeView_mainwindow->setModel(GroupProxyModel);
ui.treeView_mainwindow->setSortingEnabled(true);
Then later I fill the first row like this:
QList<QStandardItem *> items;
items.insert(0,new QStandardItem("Test 0"));
items.at(0)->setEditable(false);
m_model->insertRow(0,items);
Until now every thing working fine and I see the row with the data. But when I like to
add child to the row like this:
QModelIndex parentQModelIndex = m_model->item(0,0)->index();
m_model->insertRows(0,1,parentQModelIndex);
m_model->insertColumns(0,1,parentQModelIndex);
QModelIndex indexB = m_model->index(0, 0, parentQModelIndex);
m_model->setData(indexB,"Child test",Qt::DisplayRole);
But I don't see the child, why?
That's not how QStandardItemModel works - to add a child, call appendRow(s)/insertRow(s) on the parent QStandardItem:
QStandardItem* child = new QStandardItem( tr("Child test") );
...
QStandardItem* parentItem = m_model->item( 0, 0 );
parentItem->appendRow( child );
I have a bunch of QComboBoxes in a table. So that I know which one was triggered I remap the signal to encode the table cell location (as described in Selecting QComboBox in QTableWidget)
(Why Qt doesn't just send the cell activated signal first so you can use the same current row/column mechanism as any other cell edit I don't know.)
But this removes all knowledge of the original sender widget. Calling QComboBox* combo = (QComboBox* )sender() in the slot fails, presumably because sender() is now the QSignalMapper.
I can use the encoded row/column to lookup the QComboBox in the table widget but that seems wrong. Is there a more correct way to do it?
e.g.:
// in table creator
_signalMapper = new QSignalMapper(this);
// for each cell
QComboBox* combo = new QComboBox();
connect(combo, SIGNAL(currentIndexChanged(int)), _signalMapper, SLOT(map()));
_signalMapper->setMapping(combo, row);
// and finally
connect(_signalMapper, SIGNAL(mapped(int)),this, SLOT(changedType(int)));
// slot
void myDlg::changedType(int row)
{
QComboBox* combo = (QComboBox* )sender(); // this doesn't work !!
}
EDIT: Added for future search: there is a new book "Advanced Qt Programming" by Mark Summerfield that explains how to do this sort of thing.
Why not connect the QComboBox's signal straight to your slot?
QComboBox *combo = ...
connect(combo, SIGNAL(currentIndexChanged(int)), this, SLOT(changedType(int)));
And then in your slot you can use the sender() method to retrieve the QComboBox that was changed.
void myDlg::changedType(int row)
{
QComboBox *combo = qobject_cast<QComboBox *> sender();
if(combo != 0){
// rest of code
}
}
Alternatively, to use the QSignalMapper method you would just need to change your slot to use the mapping you set up:
void myDlg::changedType(int row)
{
QComboBox *combo = qobject_cast<QComboBox *>(_signalMapper->mapping(row));
if(combo != 0){
// rest of code
}
}
I don't know exact answer, but maybe you should use: QComboBox* combo = qobject_cast(sender()) instead of QComboBox* combo = (QComboBox* )sender(). Someting like this:
QObject* obj = sender();
QComboBox* combo = qobject_cast<QComboBox*>(obj);
if(combo)
{
doSomethingWithCombo(combo);
}
else
{
// obj is not QComboBox instance
}
But maybe QSignalMapper really substitutes itself instead of real sender...