gtk2/docs/reference/gtk/migrating-GtkIconView.sgml

<chapter id="gtk-migrating-GtkIconView">

  <title>Migrating from GnomeIconList to GtkIconView</title>

  <para>
    Since version 2.6, GTK+ provides the <link linkend="GtkIconView">GtkIconView</link>
    widget. It is similar in functionality to the GnomeIconList widget in the libgnomeui
    library, both widgets provide a way to lay out named icons in a grid. The distinctive
    feature of the GTK+ widget is that it follows the model-view pattern, allowing
    it to share the actual data (i.e. the names and images of the icons) with other
    views.
  </para>

  <para>
    <link linkend="GtkIconView">GtkIconView</link> currently doesn't support some features
    found in GnomeIconList. Icons can not be positioned freely, the spacing is not customizable,
    and it is not possible to edit the names of icons. 
  </para>

  <para>
    To convert an application that uses GnomeIconList to 
    <link linkend="GtkIconView">GtkIconView</link>, the first step is to organize your data
    in a <link linkend="GtkTreeModel">GtkTreeModel</link>. GnomeIconList lets you directly
    insert data with gnome_icon_list_insert() and gnome_icon_list_insert_pixbuf() and their
    append variants. So, if you previously had a function to fill your icon list similar
    to this one:
    <informalexample><programlisting>
      void 
      fill_icon_list (GnomeIconList *icon_list)
      {
        gnome_icon_list_append (icon_list, "file1.png", "Icon 1");
        gnome_icon_list_append (icon_list, "file2.png", "Icon 2");

        /* more icons ... */ 
      }
    </programlisting></informalexample>
    you will have to create a tree model, attach your icon view to it, and fill the model:
    <informalexample><programlisting>
      enum { 
        PIXBUF_COLUMN,
        TEXT_COLUMN,

        /* you can have more columns here, e.g */ 

        DATA_COLUMN
      };
 
      void 
      fill_model (GtkListStore *model)
      {
        GtkTreeIter iter;
        GdkPixbuf *pixbuf;

        gtk_list_store_append (model, &amp;iter);
        pixbuf = gdk_pixbuf_new_from_file ("file1.png", NULL);
        gtk_list_store_set (model, &amp;iter, PIXBUF_COLUMN, pixbuf, TEXT_COLUMN, "Icon 1", -1);
        g_object_unref (pixbuf);

        gtk_list_store_append (model, &amp;iter);
        pixbuf = gdk_pixbuf_new_from_file ("file2.png", NULL);
        gnome_icon_list_append (icon_list, PIXBUF_COLUMN, pixbuf, TEXT_COLUMN, "Icon 2", -1);
        g_object_unref (pixbuf);

        /* more icons ... */ 
      }

      int 
      main (int argc, char *argv[])
      {
        GtkWidget *icon_view;
        GtkTreeModel *model;

        gtk_init (&amp;argc, &amp;argv);

        /* do other initialization... */

        /* construct the GtkIconView */
        icon_view = gtk_icon_view_new ();
        model = gtk_list_store_new (3, GDK_TYPE_PIXBUF, G_TYPE_STRING, G_TYPE_POINTER);

        gtk_icon_view_set_pixbuf_column (GTK_ICON_VIEW (icon_view), PIXBUF_COLUMN);
        gtk_icon_view_set_text_column (GTK_ICON_VIEW (icon_view), TEXT_COLUMN);
        gtk_icon_view_set_model GTK_ICON_VIEW (icon_view), model);

        fill_model (model);

        /* ... */
      }
    </programlisting></informalexample>
    This example uses a <link linkend="GtkListStore">GtkListStore</link> as
    model, but part of the elegance of the model-view pattern is that you can easily
    use another tree model implementation, or even write your own custom tree model.
  </para>

  <para>
    Your application may make use of extra data attached to the icons in the 
    GnomeIconList via gnome_icon_list_set_icon_data() and gnome_icon_list_get_icon_data(). 
    With <link linkend="GtkIconView">GtkIconView</link> such data is most conveniently
    stored in an extra column in the tree model, so you would call a function like
    <informalexample><programlisting>
    void 
    set_icon_data (GtkIconView *icon_view,
                   gint         idx,
                   gpointer     data)
    {
       GtkTreeModel *model;
       GtkTreeIter iter;

       model = gtk_icon_view_get_model (icon_view);
    
       if (gtk_tree_model_iter_nth_child (model, &amp;iter, NULL, idx))
         gtk_list_store_set (GTK_LIST_STORE (model), &amp;iter, 
                             DATA_COLUMN, data, -1);
    }
    </programlisting></informalexample>
    assuming that your tree model has a DATA_COLUMN of type G_TYPE_POINTER.
  </para>

  <para>
    There is a number of minor API differences between GnomeIconList and GtkIconView:
    <itemizedlist> 
     <listitem><para>
       GnomeIconListMode is replaced by the orientation property of GtkIconView
     </para></listitem>
     <listitem><para>
       GtkIconView can not be frozen in the same was as GnomeIconList with 
       gnome_icon_list_freeze() and gnome_icon_list_thaw(). Instead you can 
       replace the whole model of a GtkIconView, instead of doing many small 
       changes to the existing model.
     </para></listitem>
    </itemizedlist>
  </para> 
</chapter>

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