Re: gtk_tree_model_iter_next works, what should I do about prev]

[David Nečas (Yeti) <yeti physics muni cz>]

On Wed, Aug 08, 2007 at 07:32:18AM -0600, Kevin DeKorte wrote:
> I've been having some great luck using a GtkListStore, but recently I
> wanted to see the previous node on the list. Obviously, the
> gtk_tree_model_iter_prev doesn't exist. So what is the best way to get
> the previous node.
>
> I tried something like the code below, but path was always NULL and so
> it didn't work. Any hints on this?
> // global
> GtkListStore *playliststore;
> GtkTreeIter iter;
>
> // in the callback
> GtkTreePath *path;
> gchar *filename;
> gint count;
> gint playlist;
>
> path = gtk_tree_model_get_path(GTK_TREE_MODEL(playliststore),&iter);
> if (gtk_tree_path_prev(path)) {
>       if(gtk_tree_model_get_iter(GTK_TREE_MODEL(playliststore),&iter,path)) {
>                                         gtk_tree_model_get(GTK_TREE_MODEL(playliststore), &iter,
> ITEM_COLUMN,&filename, COUNT_COLUMN,&count,PLAYLIST_COLUMN,&playlist,-1);
>                       shutdown();
>                       set_media_info(filename);
>                       play_file(filename, playlist);
>                               gtk_list_store_set(playliststore,&iter,COUNT_COLUMN,count+1, -1);
>                       g_free(filename);
>       }
> }
> gtk_tree_path_free(path);

This is not selfcontained and compilable, so it's hard to
say why it does not work.  In any case the global iter
variable is the prime suspect.  Also,
gtk_tree_model_get_path() does not normally return NULL,
doesn't it print any warning to the console?

Anyway, this works (it selects the previous row than you
clicked on):

====================================================================
#include <time.h>
#include <sys/stat.h>
#include <gtk/gtk.h>
#include <glib/gstdio.h>

enum {
    COLUMN_NAME,
    COLUMN_SIZE,
    COLUMN_DATE,
    N_COLUMNS
};

static void
fill_model(GtkListStore *store)
{
    GDir *dir;

    if ((dir = g_dir_open(".", 0, NULL))) {
        const gchar *name;

        while ((name = g_dir_read_name(dir))) {
            struct stat st;

            if (!g_stat(name, &st)) {
                guint64 time, size;
                GtkTreeIter iter;

                time = st.st_mtime;
                size = st.st_size;
                gtk_list_store_append(store, &iter);
                gtk_list_store_set(store, &iter,
                                   COLUMN_NAME, name,
                                   COLUMN_SIZE, size,
                                   COLUMN_DATE, time,
                                   -1);
            }
            /* else something */
        }
    }
    /* else something */
}

static void
render_date(G_GNUC_UNUSED GtkTreeViewColumn *column,
            GtkCellRenderer *renderer,
            GtkTreeModel *model,
            GtkTreeIter *iter,
            G_GNUC_UNUSED gpointer data)
{
    guint64 i;
    time_t time;
    struct tm *tm;
    gchar s[24];

    gtk_tree_model_get(model, iter, COLUMN_DATE, &i, -1);
    time = i;
    tm = localtime(&time);
    strftime(s, sizeof(s), "%Y-%m-%d %H:%M:%S", tm);    /* ISO 8601 */
    g_object_set(G_OBJECT(renderer), "text", s, NULL);
}

static void
selection_changed(GtkTreeSelection *selection)
{
    static gboolean in_selection_changed = FALSE;

    GtkTreeModel *model;
    GtkTreePath *path;
    GtkTreeIter iter;

    if (in_selection_changed
        || !gtk_tree_selection_get_selected(selection, &model, &iter))
        return;

    in_selection_changed = TRUE;
    path = gtk_tree_model_get_path(model, &iter);
    if (gtk_tree_path_prev(path)) {
        gtk_tree_model_get_iter(model, &iter, path);
        gtk_tree_selection_select_iter(selection, &iter);
    }
    gtk_tree_path_free(path);
    in_selection_changed = FALSE;
}

int
main(int argc,
     char *argv[])
{
    GtkWidget *window, *view, *scrlwindow;
    GtkTreeSelection *selection;
    GtkTreeViewColumn *column;
    GtkCellRenderer *renderer;
    GtkListStore *store;

    gtk_init(&argc, &argv);
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size(GTK_WINDOW(window), 360, 240);
    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

    scrlwindow = gtk_scrolled_window_new(NULL, NULL);
    gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(scrlwindow),
                                   GTK_POLICY_NEVER, GTK_POLICY_AUTOMATIC);
    gtk_container_add(GTK_CONTAINER(window), scrlwindow);

    store = gtk_list_store_new(N_COLUMNS,
                               G_TYPE_STRING, G_TYPE_INT64, G_TYPE_INT64);
    fill_model(store);
    view = gtk_tree_view_new();
    gtk_container_add(GTK_CONTAINER(scrlwindow), view);
    gtk_tree_view_set_model(GTK_TREE_VIEW(view), GTK_TREE_MODEL(store));

    renderer = gtk_cell_renderer_text_new();
    column = gtk_tree_view_column_new_with_attributes("Name", renderer,
                                                      "text", COLUMN_NAME,
                                                      NULL);
    gtk_tree_view_column_set_expand(column, TRUE);
    gtk_tree_view_append_column(GTK_TREE_VIEW(view), column);

    renderer = gtk_cell_renderer_text_new();
    g_object_set(G_OBJECT(renderer), "xalign", 1.0, NULL);
    column = gtk_tree_view_column_new_with_attributes("Size", renderer,
                                                      "text", COLUMN_SIZE,
                                                      NULL);
    gtk_tree_view_append_column(GTK_TREE_VIEW(view), column);

    renderer = gtk_cell_renderer_text_new();
    column = gtk_tree_view_column_new_with_attributes("Date", renderer,
                                                      NULL);
    gtk_tree_view_column_set_cell_data_func(column, renderer,
                                            &render_date, NULL, NULL);
    gtk_tree_view_append_column(GTK_TREE_VIEW(view), column);

    selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(view));
    gtk_tree_selection_set_mode(selection, GTK_SELECTION_BROWSE);
    g_signal_connect(selection, "changed",
                     G_CALLBACK(selection_changed), NULL);

    gtk_widget_show_all(window);
    gtk_main();

    return 0;
}
====================================================================

Yeti

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