GTK+ 3: (二) Combo Box

MVC Concept:

Control - manipulation:GtkComboBox

Model - data:GtkTreeStore or GtkListStore

View - renderer:GtkCellRenderer

GtkCellLayout interface provides the means to achieve all this.

#include <gtk/gtk.h>

/* This function gets called when currently selected item changes. */
static void cb_changed( GtkComboBox *combo, gpointer     data )
{
    GtkTreeIter   iter;
    gchar        *string = NULL;
    GtkTreeModel *model;

    /* Obtain currently selected item from combo box.
     * If nothing is selected, do nothing. */
    if( gtk_combo_box_get_active_iter( combo, &iter ) )
    {
        /* Obtain data model from combo box. */
        model = gtk_combo_box_get_model( combo );

        /* Obtain string from model. */
        gtk_tree_model_get( model, &iter, 0, &string, -1 );
    }

    /* Print string to the console - if string is NULL, print NULL. */
    g_print( "Selected (complex): >> %s <<\n", ( string ? string : "NULL" ) );

    /* Free string (if not NULL). */
    if( string )
        g_free( string );
}

/* This function deletes currently selected item from combo box. */
static void cb_delete( GtkButton   *button, GtkComboBox *combo )
{
    GtkTreeIter   iter;
    GtkListStore *store;

    /* Obtain currently selected item form combo box.
     * If nothing is selected, do nothing. */
    if( gtk_combo_box_get_active_iter( combo, &iter ) )
    {
        /* Obtain model from combo box. */
        store = GTK_LIST_STORE( gtk_combo_box_get_model( combo ) );

        /* Remove item. */
        gtk_list_store_remove( store, &iter );
    }
}



int main( int argc, char **argv )
{
    GtkWidget       *window;
    GtkWidget       *vbox;
    GtkWidget       *frame;
    GtkWidget       *combo;
    GtkWidget       *button;

    GtkListStore    *store;
    GtkTreeIter      iter;
    GtkCellRenderer *cell;

    /* Initialization */
    gtk_init( &argc, &argv );

    /* Create main window */
    window = gtk_window_new( GTK_WINDOW_TOPLEVEL );
    g_signal_connect( G_OBJECT( window ), "destroy", G_CALLBACK( gtk_main_quit ), NULL );
    gtk_container_set_border_width( GTK_CONTAINER( window ), 10 );

    /* Create vbox */
    vbox = gtk_box_new( GTK_ORIENTATION_VERTICAL, 6 );
    gtk_container_add( GTK_CONTAINER( window ), vbox );

    /* Create frame */
    frame = gtk_frame_new( "Complex API" );
    gtk_box_pack_start( GTK_BOX( vbox ), frame, FALSE, FALSE, 0 );

    /* Create data store ... */
    store = gtk_list_store_new( 1, G_TYPE_STRING );

    /* ... and fill it with some information. */
    gtk_list_store_append( store, &iter );
    gtk_list_store_set( store, &iter, 0, "Hello World once", -1 );
    gtk_list_store_prepend( store, &iter );
    gtk_list_store_set( store, &iter, 0, "Hello World twice", -1 );
    gtk_list_store_insert( store, &iter, 1 );
    gtk_list_store_set( store, &iter, 0, "Hello World last time", -1 );

    /* Create combo box with store as data source. */
    combo = gtk_combo_box_new_with_model( GTK_TREE_MODEL( store ) );
    gtk_container_add( GTK_CONTAINER( frame ), combo );

    /* Remove our reference from store to avoid memory leak. */
    g_object_unref( G_OBJECT( store ) );

    /* Create cell renderer. */
    cell = gtk_cell_renderer_text_new();

    /* Pack it into the combo box. */
    gtk_cell_layout_pack_start( GTK_CELL_LAYOUT( combo ), cell, TRUE );

    /* Connect renderer to data source. */
    gtk_cell_layout_set_attributes( GTK_CELL_LAYOUT( combo ), cell, "text", 0, NULL );

    /* Connect signal to our handler function. */
    g_signal_connect( G_OBJECT( combo ), "changed", G_CALLBACK( cb_changed ), NULL );

    /* Add button that, when clicked, deletes currently selected entry. */
    button = gtk_button_new_with_mnemonic( "_Delete selected item" );
    gtk_box_pack_start( GTK_BOX( vbox ), button, FALSE, FALSE, 0 );
    g_signal_connect( G_OBJECT( button ), "clicked", G_CALLBACK( cb_delete ), GTK_COMBO_BOX( combo ) );

    /* Show our application and start main loop. */
    gtk_widget_show_all( window );
    gtk_main();

    return( 0 );
}