[Qt-interest] Retrieve a particular item from the QTreeView

Sat Mar 26 13:22:47 CET 2011

I guess selection models work with clicked() or similar event, emitting signals when the user releases the mouse button (to allow selecting several items at once by using selection rectangle, for example).

You may want to take a look at

http://doc.qt.nokia.com/4.7/model-view-programming.html#using-drag-and-drop-with-item-views

for information about drag&drop in item views.

On Saturday 26 March 2011 15:02:12 Sajjad wrote:
> Hello Constantin,
> 
> Do you you if the selection model works only with the press event. I have to
> enable the drag and drop event with the tree views .
> But the item in the tree view only get selected with the keypress and not
> with mouse press event.
> 
> Any hint on this?
> 
> 
> Regards
> Sajjad
> 
> On Fri, Mar 25, 2011 at 9:55 PM, Sajjad <dosto.walla at gmail.com> wrote:
> 
> > Thanks Constantin,
> >
> > The hint was quite a help i must say.
> >
> > I did not get any warnings while the program was running.
> >
> >
> > Regards
> > Sajjad
> >
> > On Fri, Mar 25, 2011 at 6:47 PM, Constantin Makshin <cmakshin at gmail.com>wrote:
> >
> >> Here is a part of my application I'm currently working on:
> >>
> >> void TechniqueView::selectOperation (const QItemSelection& item)
> >> {
> >>    m_selectedOperation = item.isEmpty() ? 0 :
> >> m_model->operationIdAtRow(item.first().top());
> >>    emit selectionChanged();
> >> }
> >>
> >> TechniqueView::TechniqueView (...)
> >> {
> >>    ...
> >>    m_table = new QTableView(this);
> >>    m_model = new TechniqueModel(technique, m_table, false);
> >>    m_table->setModel(m_model);
> >>    m_table->setSelectionMode(QTableView::SingleSelection);
> >>    ...
> >>    connect(m_table->selectionModel(),
> >> SIGNAL(selectionChanged(QItemSelection, QItemSelection)),
> >> SLOT(selectOperation(QItemSelection)));
> >>    ...
> >> }
> >>
> >> Since I need to track only selected item(s), the second signal parameter
> >> is ignored.
> >> QItemSelection contains selection *ranges*, so even if the user selects
> >> all items in a view, this selection may be represented as one QItemSelection
> >> object. In my case only one item (table cell) can be selected at once, so
> >> the slot takes only the first item in the list.
> >>
> >> I admit this is somewhat simplified example of selectionChanged() signal
> >> usage, but unfortunately there's nothing [significantly] more complex I can
> >> demonstrate.
> >>
> >> On Friday 25 March 2011 19:52:14 Sajjad wrote:
> >> > Hello Constantin,
> >> >
> >> > Thanks for the hint.
> >> >
> >> > say for example i have to connect the click() signal to a slot. In my
> >> > previous post i specified how i did it.
> >> >
> >> > connect(object1, SIGNAL(clicked()),object2, use_declared_slot());
> >> >
> >> > As you have suggested, could you please any example hint either in the
> >> > QtDemos or in any other
> >> > free downloadable apps that have used selectionChanged(const
> >> > QItemSelection&,const QItemSelection&).
> >> >
> >> >
> >> > Thanks
> >> > Sajjad
> >> >
> >> > On Fri, Mar 25, 2011 at 5:02 PM, Constantin Makshin <cmakshin at gmail.com
> >> >wrote:
> >> >
> >> > > I don't know how exactly the pressed() signal of QAbstractItemView
> >> works, I
> >> > > used only clicked() signal of item views and signals emitted by
> >> selection
> >> > > models (particularly selectionChanged(QItemSelection,
> >> QItemSelection)). I
> >> > > think you should try them. And make sure you don't get any
> >> > > connection-related warning/error messages when the program is running.
> >> > >
> >> > > On Friday 25 March 2011 11:18:35 you wrote:
> >> > > > Hello Constantin,
> >> > > >
> >> > > > I gave the pressed signal a try and connected the signal to  a slot.
> >> > > > Initially the slot definition contains  a cout statement
> >> > > >
> >> > > >
> >> > > > to check if the pressed signal is actually captured. It is connected
> >> as
> >> > > > follows:
> >> > > >
> >> > > > ///////////////////////////////////////////////////////////////
> >> > > >
> >> > > >
> >> > >
> >> connect(m_h3dNodeTreeView,SIGNAL(pressed(QModelIndex)),this,SLOT(getH3DTreeItemData(QModelIndex)));
> >> > > >
> >> > > >
> >> > > > ///////////////////////////////////////////////////////////////
> >> > > >
> >> > > >
> >> > > > But withe the pressed signal i get not output. Any other hint?
> >> > > >
> >> > > >
> >> > > > Regards
> >> > > > Sajjad
> >> > > >
> >> > > > On Thu, Mar 24, 2011 at 12:24 AM, Constantin Makshin <
> >> cmakshin at gmail.com
> >> > > >wrote:
> >> > > >
> >> > > > > I can't say for sure what's the difference, but my guess is that
> >> > > pressed()
> >> > > > > is emitted when a mouse button is pressed and clicked() — when
> >> it's
> >> > > > > released.
> >> > > > >
> >> > > > > And you don't have to override mousePressEvent() as signals
> >> emitted by
> >> > > item
> >> > > > > views and selection models are more convenient, particularly
> >> because
> >> > > they
> >> > > > > provide index of the selected item.
> >> > > > >
> >> > > > > On Thursday 24 March 2011 01:08:39 Sajjad wrote:
> >> > > > > > Hello Constantin,
> >> > > > > >
> >> > > > > > Is there any difference between the signals pressed() and
> >> clicked().
> >> > > > > >
> >> > > > > > I have subclass the QTreeView as well. I was wondering if i
> >> should
> >> > > > > over-ride
> >> > > > > > the mousePressEvent() of QTreeView instead.
> >> > > > > >
> >> > > > > > Regards
> >> > > > > > Sajjad
> >> > > > > >
> >> > > > > > On Wed, Mar 23, 2011 at 10:44 PM, Constantin Makshin <
> >> > > cmakshin at gmail.com
> >> > > > > >wrote:
> >> > > > > >
> >> > > > > > > Take a look at QAbstractItemView::clicked(),
> >> > > > > QAbstractItemView::pressed()
> >> > > > > > > signals and selection model (returned by
> >> > > > > > > QAbstractItemView::selectionModel()) functions.
> >> > > > > > >
> >> > > > > > > On Thursday 24 March 2011 00:26:14 Sajjad wrote:
> >> > > > > > > > Hello forum,
> >> > > > > > > >
> >> > > > > > > > I have created a customized model by sub-classing the
> >> > > > > QAbstractItemModel
> >> > > > > > > > class and view the model in the QTreeView.
> >> > > > > > > >
> >> > > > > > > > Now when the user the click on a particular item in the tree
> >> view
> >> > > i
> >> > > > > want
> >> > > > > > > > retrieve the tree item from it.
> >> > > > > > > >
> >> > > > > > > > I have encapculated the QTreeView inside the customized
> >> widget.
> >> > > And
> >> > > > > then
> >> > > > > > > i
> >> > > > > > > > have over-ridden the mousePressEvent()
> >> > > > > > > >
> >> > > > > > > > {
> >> > > > > > > >      //I check for the left mouse press event and if not i
> >> return
> >> > > > > > > >
> >> > > > > > > >     //i need to look for the current clicked item - any way
> >> > > inside
> >> > > > > the
> >> > > > > > > > QTreeView to get it?
> >> > > > > > > > }
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > > Any hint to get it?
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