Hello Tony!
Thanks again. I do have some follow-up questions.
On Tue, Jun 26, 2012 at 12:28 PM, Tony Rietwyk <t...@rightsoft.com.au> wrote:
> Hi Frank,
>
> I haven't used QItemEditorFactory. My reading of the docs suggests this
> only applies if all of your strings are to be edited via the same combo.
> None of the interfaces include a QModelIndex, so logically it can't be used
> to provide different editors for different columns.
Yes, I was kind of worried about that. In my case my views and models
are associated with one another one to one. (That is, I don't have more
than one view connected to the same model.) All of the fields in a given
column of a view will use the same list of items in the combo box, but
different columns will have different lists of items. So whether I do it
with an editor or a delegate, I need to be able to have the editor and/or
delegate depend on the column.
> I think that means you will need to provide a QStyledItemDelegate override.
> For a given view, you can use just one item delegate for all non-standard
> columns, or have separate delegates for different columns (or rows).
In this scheme I would have different (instances of the) delegates for
different columns. Makes sense.
> I
> suggest that you load up the strings from the database only once, and store
> them in the delegate. Then you override createEditor to create the combo
> box, and add the pre-loaded items.
This part I think I understand.
> Note that delegates don't have to be specific to a particular view.
Here's where I don't understand how things work. Is a delegate
associated with a view or a model? I would think with the view
because delegates seem to do "view" kinds of things -- display
and UI interaction, rather than "model" things -- data.
In my specific case of a QTableView, is a delegate associated
with the view, with a cell in the view, or with a row or column of
the view?
Is the delegate that is associated with the view (or some part
thereof) a specific instance of a delegate class, or is it a
class (i.e., not an instance) that the machinery under the
hood somehow instantiates automatically, as needed?
And how, specifically, do I associate a delegate with a view
(or a specific part of a view)?
Let's say I derive my custom combo-box delegate from
QStyledDelegate (along the lines of your TSpinBoxDelegate
example, below). Then I instantiate my custom delegate
and load up that specific instance with the desired items
for its combo box. How to I attach that instance of that
delegate to a specific column of one of my QTableViews?
That's the part I'm fuzzy on.
> Here is
> one that I use whenever I have a column of ints with a range:
>
> class TSpinBoxDelegate : public QStyledItemDelegate
> {
> Q_OBJECT
>
> private:
> int minValue;
> int maxValue;
>
> public:
> TSpinBoxDelegate(int min, int max, QObject *parent = 0);
>
> QWidget *createEditor(
> QWidget *parent,
> const QStyleOptionViewItem &option,
> const QModelIndex &index) const;
> };
>
> ................
>
> TSpinBoxDelegate::TSpinBoxDelegate(int min, int max, QObject *parent) :
> QStyledItemDelegate(parent)
> {
> minValue = min;
> maxValue = max;
> }
>
>
> QWidget *TSpinBoxDelegate::createEditor(
> QWidget *parent,
> const QStyleOptionViewItem &option,
> const QModelIndex &index) const
> {
> Q_UNUSED( option );
> Q_UNUSED( index );
>
> QSpinBox *editor = new QSpinBox(parent);
> editor->setMinimum( minValue );
> editor->setMaximum( maxValue );
> return editor;
> }
This makes sense. I think I'm clear on how to implement a custom
delegate -- I just don't know what to do with it after I have it.
> Hope that helps,
Yes, thank you.
> Tony.
Best.
K. Frank
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