Function gtk_cell_renderer_toggle_set_active does not work properly - gtk

Question

I would like to put a Checkbox in treeview.
When I clicked the Checkbox, it should ckeck. But Checkbox keeps being not checked.
I have written a sample code in C and GTK3:
#include <gtk/gtk.h>
GtkTreeModel* create_model ()
{
GtkTreeIter gti;
GtkListStore *gls = gtk_list_store_new ( 1, G_TYPE_BOOLEAN );
gtk_list_store_append ( gls, &gti );
gtk_list_store_set ( gls, &gti, 0, FALSE, -1 );
return GTK_TREE_MODEL ( gls );
}
void check ( GtkCellRendererToggle *cell )
{
int active = gtk_cell_renderer_toggle_get_active ( cell );
g_print ( "%d\n", active );
if ( active )
{
//fail
gtk_cell_renderer_toggle_set_active (GTK_CELL_RENDERER_TOGGLE ( cell ), FALSE );
}
else
{
//fail
gtk_cell_renderer_toggle_set_active (GTK_CELL_RENDERER_TOGGLE ( cell ), TRUE) ;
}
return;
}
int main ( int argc, char *argv[] )
{
gtk_init ( &argc, &argv );
//window
GtkWidget *window_main = gtk_window_new ( GTK_WINDOW_TOPLEVEL );
//tree view
GtkWidget *treeview = gtk_tree_view_new_with_model ( create_model () );
//cell_renderer_toggle
GtkCellRenderer *cell = gtk_cell_renderer_toggle_new ();
gtk_tree_view_append_column ( GTK_TREE_VIEW ( treeview ), gtk_tree_view_column_new_with_attributes ( "test", cell, "active", 0, NULL ) );
g_signal_connect ( cell, "toggled", G_CALLBACK ( check ), NULL );
gtk_container_add ( GTK_CONTAINER ( window_main ), treeview );
gtk_widget_show_all ( window_main );
gtk_main();
return 0;
}
Function gtk_cell_renderer_toggle_set_active call fails and does not set the cell active.
Please help me fix my code.

Answer 1

With the call of
gtk_tree_view_column_new_with_attributes ("test", cell, "active", 0, NULL);
you bind the "active" property of each cell renderer in any row of the column to the value in the first column of the related data model. Although the state of any GtkCellRendererToggle instance is represented by its own properties its "active" property reflects the corresponding value in the data model at the same time.
If you activate a single cell renderer by means of gtk_cell_renderer_toggle_set_active you just set the "active" property of the specific GtkCellRendererToggle instance. Unfortunately the instance has no knowledge about the data model from which it represent a value and therefore has no access to it. That means that on the next draw of the treeview the "active" property corresponds with the related value from the data model again. Your change is simply overwritten.
Nevertheless you can still safely set all other properties of a cell renderer that are not connected to the data model. I included an example for that in my example.
That means that your callback have to change the value in the data model instead of changing the property of the cell renderer.
The appended modification of your example code illustrates what i've described
#include <gtk/gtk.h>
GtkListStore *
create_model ()
{
GtkTreeIter gti;
GtkListStore *gls;
gls = gtk_list_store_new (1, G_TYPE_BOOLEAN);
gtk_list_store_append (gls, &gti);
gtk_list_store_set (gls, &gti, 0, TRUE, -1);
return gls;
}
void
check (GtkCellRendererToggle * cell, gchar * path, GtkListStore * model)
{
GtkTreeIter iter;
gboolean active;
active = gtk_cell_renderer_toggle_get_active (cell);
gtk_tree_model_get_iter_from_string (GTK_TREE_MODEL (model), &iter, path);
if (active) {
gtk_cell_renderer_set_alignment(GTK_CELL_RENDERER(cell), 0, 0);
gtk_list_store_set (GTK_LIST_STORE (model), &iter, 0, FALSE, -1);
}
else {
gtk_cell_renderer_set_alignment(GTK_CELL_RENDERER(cell), 0.5, 0.5);
gtk_list_store_set (GTK_LIST_STORE (model), &iter, 0, TRUE, -1);
}
}
int
main (int argc, char *argv[])
{
GtkTreeViewColumn *column;
GtkWidget *window_main;
GtkWidget *treeview;
GtkCellRenderer *cell;
GtkListStore *store;
gtk_init (&argc, &argv);
store = create_model ();
//window
window_main = gtk_window_new (GTK_WINDOW_TOPLEVEL);
//tree view
treeview = gtk_tree_view_new_with_model (GTK_TREE_MODEL (store));
//cell_renderer_toggle
cell = gtk_cell_renderer_toggle_new ();
column =
gtk_tree_view_column_new_with_attributes ("test",
cell, "active", 0, NULL);
gtk_tree_view_append_column (GTK_TREE_VIEW (treeview), column);
g_signal_connect (cell, "toggled", G_CALLBACK (check), store);
g_signal_connect (window_main, "destroy",
G_CALLBACK (gtk_main_quit), NULL);
gtk_container_add (GTK_CONTAINER (window_main), treeview);
gtk_widget_show_all (window_main);
gtk_main ();
return 0;
}