I have a QTableWidget with SelectionMode set to SingleSelection, and SelectionBehavior set to SelectColumns. This means that only a single column can be selected.
But I later need to find out which column is selected, and the only functions I can use are selectedIndexes() or selectedItems(), both of which return entire lists, which is wasteful.
Is there a way to do this more efficiently?
Your approach with the selectedItems() was correct.
As QT cant know that you've set your widget to singlerow/column selection it offers those functions to return a QList<>.
in your case you can work on those by using .first().
Evne though I suggest to use the signals currentColumnChanged() to react in your application
( http://harmattan-dev.nokia.com/docs/library/html/qt4/qitemselectionmodel.html#currentColumnChanged )
you could always iterate over all columns of the selected row via selectionModel()->isColumnSelected()
( http://qt-project.org/doc/qt-4.8/qitemselectionmodel.html#isColumnSelected )
connect(tableWidget, SIGNAL(currentCellChanged(int,int,int,int), this, SLOT(onCellChanged(int,int,int,int)));
void Class::onCellChanged(int curRow, int curCol, int preRow, int preCol)
{
current_Col = curCol;
// curRow, preRow and preCol are unused
}
connect(tableWidget->selectionModel()
, SIGNAL(currentColumnChanged(QModelIndex,QModelIndex))
, SLOT(onColumnChanged(QModelIndex)));
...
void Class::onColumnChanged(const QModelIndex &index)
{
int col = index.column();
}
It seems that the function selectedRanges() does what I need. It returns a list of the selected ranges, but since it's a single column, this list would have only one item (so it's efficient, no big list need to be created).
int column = ui->tableWidget->selectedRanges().front().leftColumn();
currentColumn() returns an int of the current selected column.
Related
I have a QStandardItemModel with a single column (represents a list). Each item in the list has a unique integer ID stored as the QStandardItem's data (via QStandardItem::setData which I guess is into Qt::UserRole+1 by default).
Given one of these IDs, I'd like to find and remove the corresponding row from the model. Right now I'm doing this:
void NetworkManager::removeSessionFromModel (QStandardItemModel *model, int sessionId) {
foreach (const QStandardItem *item, model->findItems("*", Qt::MatchWildcard)) {
if (item->data() == sessionId) {
model->removeRow(item->index().row());
break;
}
}
}
It works fine, but every single line of that function makes me cringe. Is there a cleaner way to do any of this?
How about traversing the QStandardItemModel directly? Something like this:
void NetworkManager::removeSessionFromModel (QStandardItemModel *model, int sessionId)
{
for (int i = 0; i < model->rowCount(); ++i)
{
if (model->item(i)->data() == sessionId)
{
model->removeRow(i);
break;
}
}
}
Not sure how QStandardItemModel behaves with random access, maybe your method is more efficient.
Edit:
Actually, there is a function to do what you want: QAbstractItemModel::match
It returns a QModelIndexList with all entries that have matching data in a given role.
void NetworkManager::removeSessionFromModel (QStandardItemModel *model, int sessionId)
{
QModelIndexList list = model->match(model->index(0, 0), Qt::UserRole + 1, sessionId);
if (!list.empty())
model->removeRow(list .first().row());
}
Setting data to a specific role can be done as follows:
model->setData(model->index(row, col), QVariant(13), Qt::UserRole + 1);
You need to get the row index from your item id.
A more effective way could be to use a QMap with the row index as value and the item id as a key.
In this case, you also need to maintain the map values every time you add/remove a row.
If you don't have 3 millions items in your list, just keep it simple and use your code.
By optimize this code, you probably also add complexity and reduce maintainability, and you get is 0,05 ms instead of 0,06 ms.
In GUI code, I often have code like this : it's simple, everyone get it immediatly and it does the job. It' also fast enough.
You're using findItems wrong, it can already return the item you want just by passing the value you're searching for. If you call it like you're doing right now you're looping through your items at least two times, since findItems must iterate through all the items to find those that match your pattern, in your case all items match, then you iterate the returned items again to find the sessionId.
void NetworkManager::removeSessionFromModel (QStandardItemModel *model, int sessionId) {
auto items = model->findItems(QString::number(sessionId));
if (!items.empty()) {
auto row = items.first()->index().row();
model->removeRow(row);
}
}
Alternatively you can use the match method since findItems uses that internally, so you avoid allocating the StandardItem just to get its index. Also match returns right after the number of items matching the pattern, in this case the value of sessionId, are found so it doesn't always iterate all the items; that's more efficient. Obviously if the value is not found after iterating all the items it returns an empty list.
auto start = model->index(0, 0);
auto indexes = model->match(start, Qt::UserRole + 1, QString::number(sessionId), 1, Qt::MatchExactly);
if (!indexes.empty()) {
auto row = indexes.first().row();
model->removeRow(row);
}
When I use Qt tableView, I can just set item in the first row. When I click add, it will cover the former, but not set a new item. Maybe my slot function is incorrect. But I don't know how to handle it.
void Widget::on_addButton_clicked()
{ int i = 0;
EditDialog editDialog(this);
if(editDialog.exec() == 1)
{
model->setItem(i,0,new QStandardItem(editDialog.getID()));
model->setItem(i,1,new QStandardItem(editDialog.getPriority()));
model->setItem(i,2,new QStandardItem(editDialog.getTime()));
}
i++;
}
Please, have a look into doc. QStandardItemModel::setItem():
Sets the item for the given row and column to item. The model takes ownership of the item. If necessary, the row count and column count are increased to fit the item. The previous item at the given location (if there was one) is deleted.
(Emphasizing is mine.)
If a row shall be inserted before end of table (e.g. as first), then it's necessary to do this explicitly.
This can be achieved by calling QStandardItemModel::insertRow() before setting the items.
This could e.g. look like this:
// fills a table model with sample data
void populate(QStandardItemModel &tblModel, bool prepend)
{
int row = tblModel.rowCount();
if (prepend) tblModel.insertRow(0);
for (int col = 0; col < NCols; ++col) {
QStandardItem *pItem = new QStandardItem(QString("row %0, col %1").arg(row).arg(col));
tblModel.setItem(prepend ? 0 : row, col, pItem);
}
}
I took this from an older post of mine. The complete sample can be found in my answer to SO: Stop QTableView from scrolling as data is added above current position.
I am trying to get the id of the record in the model from a QCombobox with findData(index), but when select a item, it retunrs -1. It has been working in another project, but this is the second one that doesn't work. Here's my code:
modAnfi = new QSqlTableModel(this);
modAnfi->setQuery("SELECT id, (nombres || ' ' || apellidos) as Nombre, nombres, apellidos FROM tbPersonas WHERE activo=1");
comboAnfitrion->setModel(modAnfi);
comboAnfitrion->setModelColumn(1);
comboAnfitrion->setEditable(true);
comboAnfitrion->completer()->setCompletionMode(QCompleter::PopupCompletion);
connect(comboAnfitrion, SIGNAL(currentIndexChanged(int)), this, SLOT(currentIndexChangeAnfitrion(int)));
and:
void controlReg::currentIndexChangeAnfitrion(int index)
{
qDebug() << comboAnfitrion->findData(index); // -1
qDebug()<< comboAnfitrion->itemData(1); // QVariant(Invalid)
}
Thanks for your time, any help will be appreciated.
You have to use the model you assign to the comboBox, use the index to look for it:
modAnfi->data(modAnfi->index( index, 0));
Check the QComboBox documentation; from the findData description, quoting:
Returns the index of the item containing the given data
Where you are passing index as the "given data". However, index is already an index in the combobox. But you're obviously not looking for an index (since you already have one).
I suspect you actually want to call the itemData method instead? That would retrieve the data associated with an element for a given index.
My row has 5 columns and I need the data from the last column. I've written the below function. This function should return the element from the last column of the selected row, but unfortunately, after debug I've noticed that my function only reads the first column. Can anyone help me to solve this?
QString MainWindow::getIDNumberFromSelectedRow(const QModelIndexList indexes)
{
QStringList selected_text;
foreach(QModelIndex current,indexes)
{
QVariant data = model->data(current);
QString text = data.toString();
selected_text.append(text);
qDebug() << text;
}
QString idNumber = selected_text.last();
return idNumber;
}
Possibly, indexes, and thus, current(s) refers to the first column of the model.
What if you refer directly to a specific item, e.g:
model->data(model->index(current.row(), 4))
I don't know if this work, anyway I hope it'll help
I am trying to delete all rows from a QTableWidget . Here is what I tried.
for ( int i = 0; i < mTestTable->rowCount(); ++i )
{
mTestTable->removeRow(i);
}
I had two rows in my table. But this just deleted a single row. A reason could be that I did not create the the table with a fixed table size. The Qt Documentation for rowCount() says,
This property holds the number of rows in the table.
By default, for a table constructed without row and column counts,
this property contains a value of 0.
So if that is the case, what is the best way to remove all rows from table?
Just set the row count to 0 with:
mTestTable->setRowCount(0);
it will delete the QTableWidgetItems automatically, by calling removeRows as you can see in QTableWidget internal model code:
void QTableModel::setRowCount(int rows)
{
int rc = verticalHeaderItems.count();
if (rows < 0 || rc == rows)
return;
if (rc < rows)
insertRows(qMax(rc, 0), rows - rc);
else
removeRows(qMax(rows, 0), rc - rows);
}
I don't know QTableWidget but your code seems to have a logic flaw. You are forgetting that as you go round the loop you are decreasing the value of mTestTable->rowCount(). After you have removed one row, i will be one and mTestTable->rowCount() will also be one, so your loop stops.
I would do it like this
while (mTestTable->rowCount() > 0)
{
mTestTable->removeRow(0);
}
AFAIK setRowCount(0) removes nothing. Objects are still there, but no more visible.
yourtable->model()->removeRows(0, yourtable->rowCount());
QTableWidget test;
test.clear();
test.setRowCount( 0);
The simple way to delete rows is to set the row count to zero. This uses removeRows() internally.
table->setRowCount(0);
You could also clear the content and then remove all rows.
table->clearContents();
table->model()->removeRows(0, table->rowCount());
Both snippets leave the headers untouched!
If you need to get rid of headers, too, you could switch from clearContents() to clear().
In order to prevent an app crash, disconnect all signals from the QTableView.
// Deselects all selected items
ui->tableWidget->clearSelection();
// Disconnect all signals from table widget ! important !
ui->tableWidget->disconnect();
// Remove all items
ui->tableWidget->clearContents();
// Set row count to 0 (remove rows)
ui->tableWidget->setRowCount(0);
Look this post : http://forum.qt.io/topic/1715/qtablewidget-how-to-delete-a-row
QList<QTableWidgetItem*> items = table.findItems(.....);
QMap<int, int> rowsMap;
for(int i = 0; i < items.count(); i++{
rowsMap[items.at(i).row()] = -1; //garbage value
}
QList<int> rowsList = rowsMap.uniqueKeys();
qSort(rowsList);
//Now go through your table and delete rows in descending order as content would shift up and hence cannot do it in ascending order with ease.
for(int i = rowList.count() - 1; i >= 0; i--){
table.removeRow(rowList.at(i));
}
You can just add empty item model (QStandardItemModel) to your QTableView (myTableView):
itemModel = new QStandardItemModel;
ui->myTableView->setModel(itemModel);
In python you can just set the rowCount to zero and that'll work!
tableWidget.setRowCount(0)
This code is tested with PySide6. Hope it will work for PyQt5 and PyQt6 too.
Your code does not delete last row.
Try this one.
int totalRow = mTestTable->rowCount();
for ( int i = 0; i < totalRow ; ++i )
{
mTestTable->removeRow(i);
}
In your code, on the first time, rowCount() have value 2 and value of the i is 0, so its delete 1st row,
But on the second time value of i incremented with 1, but rowCount() return the updated row count which is now 1, so, it does not delete the last row.
Hope now you ll be clear.
Removes all items not in the headers from the view. This will also remove all selections. The table dimensions stay the same.
void QTableWidget::clearContents()
Removes all items in the view. This will also remove all selections and headers.
void QTableWidget::clear()
This works for me:
for i in reversed(range(self.tableWidget.rowCount())):
self.tableWidget.removeRow(i)