I have got a number of QComboBoxes. Suppose that we have one combobox with index i and another combobox with index j. If user activate index j in the first combobox I want the second combobox index to be changed to i, so that there no equal indexes in all comboboxes. What is the easiest way to do it? I have tryed to do it with SIGNALS AND SLOTS approach:
for(int i=0;i<boxes.size();++i){
connect(boxes[i], SIGNAL(activated(int)),this,SLOT(boxIndexChanged(int)));
}
where boxes is a QList<QComboBox*> the problem here is that i don't know in slot function boxIndexChanged(int index) which combobox have emited signal(I need it in the case if there are identical indexes in two combobox).
You have at least two options:
Use QObject::sender() to get a pointer to object which emitted a signal. Please note, that it's a simple, but not recommended way (see method's documentation).
Use QSignalMapper.
Related
My friends, Could you please explain the concept of these methods to me? Normally, when I get a data I would use 'index' to refer to items in a model and specify roles via data attribute. I came across 'item' method today and the explanation of this method is "Returns the item for the given row and column if one has been set; otherwise returns 0." What are differences from 'index'+'data' method? Is it just a shortcut?
This is the documentation of 'item' method.
https://doc.qt.io/qt-5/qstandarditemmodel.html#item
Alternatively, this is the documentation of 'index' method.
https://doc.qt.io/qt-5/qstandarditemmodel.html#index
I'll try my best to explain it.
The item is like the actual widget you see in the view (it's not actually a widget, but I think it's a good way to think about it). It's what the user is actually seeing.
The index is more "behind the scenes." It's like a pointer to a position in the model.
An item can exist without an index. But a valid index cannot exist without an item. The item only associates with an index when it is put into a model. Otherwise, it's just an item that no one can look at.
Take an array as an example... It contains multiple "items". You specify which item from the array you want by providing a number, aka the index. Simply put, the index only exists when it is associated with an item in the array. But the item can exist outside of the array and be it's own thing without an index.
The QModelIndex was created to be a lightweight way to reference items in a model. Similar to the way you can use a number to represent an object stored in an array.
In my app I'd like to insert an item at the top of a QTreeView.
What I have so far will insert an item just above the currently selected item. The code (nicked, I think, from the EditableTreeviewDemo):
QModelIndex index = this->selectionModel()->currentIndex();
QAbstractItemModel *model = this->model();
if (!model->insertRow(index.row(), index.parent()))
return;
I guess what I need is the index to the current first row? How do I get this?
As a side question, what happens to the current index when a row is inserted? Does it continue to point to the same item, or the same row?
Well first you have to know that insertRow is a function from QAbstractItemModel and it will call insertRows (with an s). This function must be redefined in your model subclass if you want to allow insertion of data in your model.
http://doc.qt.io/qt-5/qabstractitemmodel.html#insertRows
Also consider that any parent of a topmost index is a invalid QModelIndex. Then the call to do would be :
model->insertRow(0, QModelIndex());
And because this is the default value for the second parameter, simply call :
model->insertRow(0);
Then in your redefinition of insertRows simply check the validity of you parent index to ensure you news underlying data is created where you want it to be.
For you question, inserting data in the model won't affect the current and selected items.
Within an already-instantiated QAbstractListModel subclass, how do I add a row with data in each column, and have the associated QListView display the new row?
It seems that the only way to do it is to reimplement insertRow and setData within my model, and then hack them together in some sort of sequence within another function to add a row. Must I do this? Surely Qt must make it easier to add a new row.
Thanks much!
--Dany.
Just change your model's data storage, in between beginInsertRows() and endInsertRows().
For instance, let's say you have a flat list model and your model stores the data internally in a QVector m_data. You want to prepend the list, i.e. insert a row at position 0:
beginInsertRows( QModelIndex(), 0, 0 ); //notify views and proxy models that a line will be inserted
m_data.prepend( somedata ); // do the modification to the model data
endInsertRows(); //finish insertion, notify views/models
I'm afraid you have to do it that way. From the docs:
Models that provide interfaces to resizable list-like data structures can provide implementations of insertRows() and removeRows().
I'm using PyQt to create a GUI application. In a view inherited from QTableView, need to detect the row the user has selected when they double click a row. The table has sorting, but no editing.
How do I do it?
Note - tried the doubleClicked(int) signal. It is emitted by mouse buttons, not by data cells, so it was never fired. :(
Ian
I dont understand.
The doubleClicked signal of the QTableView has the signature
void doubleClicked ( const QModelIndex & index )
If you connect that signal you should obtain the correct QModelIndex.
No need to use SIGNALs anymore:
self.your_table.doubleClicked.connect(your_function)
"doubleClicked" being inherited from QAbstractItemView.
Once you have the modelIndex, (from Frank's comment above) you can use it to find which cell was double clicked.
def slotDoubleClicked(self, mi):
row = mi.row()
column = mi.column()
You then can use these row and col values to access the table with table.setItem(row, column, newdata) or other table method
Like #regomodo said, you can simply connect your function to the double click via:
self.your_table.doubleClicked.connect(your_function)
Then, if you want to know on which row the user double clicked, you can use the following code:
for idx in self.your_table.selectionModel().selectedIndexes():
row_number = idx.row()
column_number = idx.column()
It will return an integer corresponding to the row or the column number.
There will always only be a single value as the double click remove the previous selection.
If you link your function to a push button or another signal, you can receive a list containing multiple elements selected by the user.
For example, you can easily retrieve a list of all selected rows using this code:
rows = []
for idx in self.your_table.selectionModel().selectedIndexes():
rows.append(idx.row())
rows = list(set(rows))
This will return a list of all selected rows (The set function will also remove any duplicates).
Cheers!
I have a QTreeView which has the ExtendedSelection attribute (users may select more than one non-contiguous range of cells).
I would like my app to allow them to select these multiple cells and then enter a value and have all the cells take that value.
My issue is that I don't know how to get the full range of cells passed to my model. Right now the index that is passed to the setData method is only the active cell, not the full range of selected cells.
In the past, I have had my view store the currently selected range in the model every time it changes, and then use that to control which cells to modify. This seems kind of hacky and I wonder whether anyone has a better and more elegant solution.
I am using PyQt by the way, though I suspect this applies to QT by itself.
Thanks!
I believe you can use selectionModel method of the QAbstractItemView class to iterate through selected indexes and change values of the corresponding cells. Below is a small example:
foreach (QModelIndex index, ui->treeView->selectionModel()->selectedIndexes())
{
qDebug() << "Changing index " << index.row();
ui->treeView->model()->setData(index, "new data");
}
hope this helps, regards