maemo.org - Talk - HildonTouchSelector and gtk_list_store

I noticed a behavior that I believe was introduced in the recent updates of SDK to PR1.2. I have used gtk_list_store_clear to clear a list store associated with a touch selector. Now it seems that gtk_list_store_clear emits several times the "value-changed" signal for the picker button of the touch selector. I tried to block the signal by using g_signal_handlers_block_by_func/g_signal_handlers_unblock_by_func around gtk_list_store_clear but the signal is still emitted.

Here is a simple example which should demonstrate the behaviour.

Code:

/*

 * This file is adapted from Hildon Tutorial Examples

 *

 * Copyright (C) 2009 Nokia Corporation. All rights reserved.

 *

 * This maemo code example is licensed under a MIT-style license,

 * that can be found in the file called "COPYING" in the package

 * root directory.

 *

 */



#include                                        <hildon/hildon.h>



void value_changed (GtkWidget *widget, gpointer user_data)

{

  gint current_selection;

  HildonTouchSelector *selector;



  g_printerr("%s() start\n",__PRETTY_FUNCTION__);



  selector = hildon_picker_button_get_selector(HILDON_PICKER_BUTTON(widget));

  current_selection = hildon_touch_selector_get_active (selector, 0);

  g_printerr ("Current selection : %d\n", current_selection);



  g_printerr("%s() end\n",__PRETTY_FUNCTION__);

}



void fill_simple_selector(GtkWidget *selector)

{

  gint i;



  for (i = 1; i <= 5 ; i++) {

    gchar *label = g_strdup_printf ("Item %d", i);



    /* Add item to the column */

    hildon_touch_selector_append_text (HILDON_TOUCH_SELECTOR (selector),

                                       label);



    g_free (label);

  }

}



static GtkWidget *create_simple_selector (void)

{

  GtkWidget *selector = NULL;



  /* Create a HildonTouchSelector with a single text column */

  selector = hildon_touch_selector_new_text();



  /* Populate selector */

  fill_simple_selector(selector);



  return selector;

}



void button_clicked( GtkWidget *widget,  gpointer user_data)

{

  GtkTreeModel *model;

  HildonTouchSelector *selector;



  g_printerr("%s() start\n",__PRETTY_FUNCTION__);



  selector = hildon_picker_button_get_selector(HILDON_PICKER_BUTTON(user_data));



  /* The following should inhibit the value_changed callback to be called ... */

  g_signal_handlers_block_by_func(selector, G_CALLBACK(value_changed), NULL);



  model = hildon_touch_selector_get_model(HILDON_TOUCH_SELECTOR(selector), 0);

  gtk_list_store_clear(GTK_LIST_STORE(model));

  fill_simple_selector(GTK_WIDGET(selector));



  /* ...until unblocked here*/

  g_signal_handlers_unblock_by_func(selector, G_CALLBACK(value_changed), NULL);



  g_printerr("%s() end\n",__PRETTY_FUNCTION__);

}



int main (int argc, char **argv)

{

  HildonProgram *program = NULL;

  GtkWidget *window = NULL;

  GtkWidget *selector = NULL;

  GtkWidget *box = NULL;

  GtkWidget *picker_button = NULL;

  GtkWidget *button = NULL;



  hildon_gtk_init (&argc, &argv);



  program = hildon_program_get_instance ();

  g_set_application_name

    ("hildon-touch-selector example program");



  window = hildon_stackable_window_new ();

  hildon_program_add_window (program, HILDON_WINDOW (window));



  box = gtk_vbox_new(FALSE, 5);

  gtk_container_add (GTK_CONTAINER (window), box);



  /* Create touch selector */

  selector = create_simple_selector ();



  /* Create a picker button */

  picker_button = hildon_picker_button_new (HILDON_SIZE_AUTO,

                                            HILDON_BUTTON_ARRANGEMENT_VERTICAL);



  /* Set a title to the button*/

  hildon_button_set_title (HILDON_BUTTON (picker_button), "Select an item");



  /* Attach touch selector to the picker button*/

  hildon_picker_button_set_selector (HILDON_PICKER_BUTTON (picker_button),

                                     HILDON_TOUCH_SELECTOR (selector));



  g_signal_connect(G_OBJECT(picker_button), "value-changed",

                   G_CALLBACK(value_changed), NULL);



  /* Add button to main window */

  gtk_box_pack_start (GTK_BOX (box), picker_button, TRUE, TRUE, 0);



  button = hildon_button_new_with_text (HILDON_SIZE_AUTO, 

                                        HILDON_BUTTON_ARRANGEMENT_VERTICAL,

                                        "Refill touch selector",

                                        NULL);

  g_signal_connect(G_OBJECT(button), "clicked",

                   G_CALLBACK(button_clicked), picker_button);

  gtk_box_pack_start (GTK_BOX (box), button, TRUE, TRUE, 0);



  g_signal_connect (G_OBJECT (window), "destroy",

                    G_CALLBACK (gtk_main_quit), NULL);



  gtk_widget_show_all (GTK_WIDGET (window));



  gtk_main ();



  return 0;

}

Compile the code with

Code:

gcc -o hildon-touch-selector-example hildon-touch-selector-example.c `pkg-config gtk+-2.0 hildon-1 --cflags --libs` -Wall

Pressing the "Refill touch selector" button should first clear the touch selector list store and then refill it with the same date. As seen, the value-changed callback (function value_changed()) is called while the button_clicked() callback is running.

Have I understood something wrong? I wouldn't like to use the "changed" callback for the touch selector since it created some problems in my code (not the simple example above).