Re: Removing selected items from a list

[Christopher Backhouse <cjbackhouse gmail com>]

I like option 2. Strange that I didn't think of it, as this exactly what 
I usually do for std::vector (although the performance of deleting from 
the middle of a vector is obviously not good)

David NeÄas (Yeti) wrote:
> On Fri, Jul 21, 2006 at 11:23:40PM +0100, Christopher Backhouse wrote:
> > so - I loop through the selection, converting all the paths into 
> > references and put them in a new list.
> > Then I loop through that list, convert the references back to iters so i 
> > can remove them from the tree.
> > It also seems to be impossible to convert a reference to an iter - so I 
> > have to go via a path.
> > All in all not the prettiest code, but at least it works.
> > If there is a neater solution I would be happy to hear about it
>
> This method is quite general, but it has indeed a large
> overhead.  See the attached example for two simplier
> methods.
>
> Yeti
>
>
> --
> Anonyms eat their boogers.
>
>
> ==========================================================================
> #include <gtk/gtk.h>
>
> static void
> add_iter(GtkTreeModel *model,
>          GtkTreePath *path,
>          GtkTreeIter *piter,
>          gpointer userdata)
> {
>     GArray *sel = (GArray*)userdata;
>     GtkTreeIter iter = *piter;
>
>     g_array_append_val(sel, iter);
> }
>
> static void
> remove1(GtkTreeSelection *selection)
> {
>     GtkTreeView *treeview;
>     GtkListStore *store;
>     GArray *sel;
>     guint i;
>
>     treeview = gtk_tree_selection_get_tree_view(selection);
>     store = GTK_LIST_STORE(gtk_tree_view_get_model(treeview));
>
>     sel = g_array_new(FALSE, FALSE, sizeof(GtkTreeIter));
>     /* This needs persistent iters */
>     gtk_tree_selection_selected_foreach(selection, add_iter, sel);
>     gtk_tree_selection_unselect_all(selection);
>     for (i = 0; i < sel->len; i++) {
>         GtkTreeIter *iter = &g_array_index(sel, GtkTreeIter, i);
>
>         gtk_list_store_remove(store, iter);
>     }
>     g_array_free(sel, TRUE);
> }
>
> static void
> remove2(GtkTreeSelection *selection)
> {
>     GtkTreeModel *model;
>     GtkListStore *store;
>     GList *sel, *l;
>
>     sel = gtk_tree_selection_get_selected_rows(selection, &model);
>     gtk_tree_selection_unselect_all(selection);
>     store = GTK_LIST_STORE(model);
>     /* This assumes paths are in order.  Although it works there is no such
>      * guarantee in Gtk+ API docs, so maybe a sort is necessary. */
>     sel = g_list_reverse(sel);
>     for (l = sel; l; l = g_list_next(l)) {
>         GtkTreeIter iter;
>         GtkTreePath *path = (GtkTreePath*)l->data;
>
>         gtk_tree_model_get_iter(model, &iter, path);
>         gtk_list_store_remove(store, &iter);
>         gtk_tree_path_free(path);
>     }
>     g_list_free(sel);
> }
>
> /* This is gross */
> static void
> fill(GtkListStore *store)
> {
>     GtkTreeIter iter;
>     guint i;
>
>     gtk_list_store_clear(store);
>
>     for (i = 0; i < 20; i++) {
>         gtk_list_store_append(store, &iter);
>         gtk_list_store_set(store, &iter, 0, i, -1);
>     }
> }
>
> int
> main(int argc, char *argv[])
> {
>     GtkWidget *window, *treeview, *vbox, *button;
>     GtkTreeViewColumn *column;
>     GtkCellRenderer *renderer;
>     GtkTreeSelection *selection;
>     GtkListStore *store;
>
>     gtk_init(&argc, &argv);
>
>     store = gtk_list_store_new(1, G_TYPE_UINT);
>     fill(store);
>
>     window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
>     g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
>
>     vbox = gtk_vbox_new(FALSE, 0);
>     gtk_container_add(GTK_CONTAINER(window), vbox);
>
>     treeview = gtk_tree_view_new_with_model(GTK_TREE_MODEL(store));
>     gtk_tree_view_set_headers_visible(GTK_TREE_VIEW(treeview), FALSE);
>
>     renderer = gtk_cell_renderer_text_new();
>     column = gtk_tree_view_column_new();
>     gtk_cell_layout_pack_start(GTK_CELL_LAYOUT(column), renderer, TRUE);
>     gtk_cell_layout_add_attribute(GTK_CELL_LAYOUT(column), renderer, "text", 0);
>     gtk_tree_view_append_column(GTK_TREE_VIEW(treeview), column);
>     gtk_box_pack_start(GTK_BOX(vbox), treeview, TRUE, TRUE, 0);
>
>     selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(treeview));
>     gtk_tree_selection_set_mode(selection, GTK_SELECTION_MULTIPLE);
>
>     button = gtk_button_new_from_stock(GTK_STOCK_REMOVE);
>     gtk_box_pack_start(GTK_BOX(vbox), button, FALSE, FALSE, 0);
>     g_signal_connect_swapped(button, "clicked", G_CALLBACK(remove1), selection);
>
>     button = gtk_button_new_from_stock(GTK_STOCK_DELETE);
>     gtk_box_pack_start(GTK_BOX(vbox), button, FALSE, FALSE, 0);
>     g_signal_connect_swapped(button, "clicked", G_CALLBACK(remove2), selection);
>
>     button = gtk_button_new_with_mnemonic("_Fill");
>     gtk_box_pack_start(GTK_BOX(vbox), button, FALSE, FALSE, 0);
>     g_signal_connect_swapped(button, "clicked", G_CALLBACK(fill), store);
>
>     gtk_widget_show_all(window);
>     gtk_main();
>
>     return 0;
> }
>
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