ListItemFactory#
Superclasses: Object
Subclasses: BuilderListItemFactory
, SignalListItemFactory
A GtkListItemFactory
creates widgets for the items taken from a GListModel
.
This is one of the core concepts of handling list widgets such
as ListView
or GridView
.
The GtkListItemFactory
is tasked with creating widgets for items
taken from the model when the views need them and updating them as
the items displayed by the view change.
A view is usually only able to display anything after both a factory and a model have been set on the view. So it is important that you do not skip this step when setting up your first view.
Because views do not display the whole list at once but only a few
items, they only need to maintain a few widgets at a time. They will
instruct the GtkListItemFactory
to create these widgets and bind them
to the items that are currently displayed.
As the list model changes or the user scrolls to the list, the items will change and the view will instruct the factory to bind the widgets to those new items.
The actual widgets used for displaying those widgets is provided by you.
When the factory needs widgets created, it will create a GtkListItem
and hand it to your code to set up a widget for. This list item will provide
various properties with information about what item to display and provide
you with some opportunities to configure its behavior. See the
ListItem
documentation for further details.
Various implementations of GtkListItemFactory
exist to allow you different
ways to provide those widgets. The most common implementations are
BuilderListItemFactory
which takes a GtkBuilder
.ui file
and then creates widgets and manages everything automatically from the
information in that file and SignalListItemFactory
which allows
you to connect to signals with your own code and retain full control over
how the widgets are setup and managed.
A GtkListItemFactory
is supposed to be final - that means its behavior should
not change and the first widget created from it should behave the same way as
the last widget created from it.
If you intend to do changes to the behavior, it is recommended that you create
a new GtkListItemFactory
which will allow the views to recreate its widgets.
Once you have chosen your factory and created it, you need to set it
on the view widget you want to use it with, such as via
set_factory
. Reusing factories across different
views is allowed, but very uncommon.