GUI development

Foreword

Almost everything in NavIt works as a plugin, and so do the guis.

Initializing your gui

You have to provide a function plugin_init in your plugin.

This function should call

plugin_register_gui_type("gui-name", function);

The function has the following parameters: struct gui_methods *meth, int w, int h

• meth is a structure with gui-functions you have to fill

• w is the expected width

• h is the expected height of the gui.

But you might ignore w and h, they are only recommendations.

meth should be filled with the following data:

• menubar_new

• toolbar_new

• statusbar_new

• popup_new

• set_graphics

You can probably implement menubar_new, toolbar_new, statusbar_new and popup_new as a dummy, since it is rather GTK-specific, but set_graphics is required. It connects the graphics to the gui.

struct gui_methods gui_<plugin>_methods = {
   gui_<plugin>_menubar_new,
   gui_<plugin>_toolbar_new,
   gui_<plugin>_statusbar_new,
   gui_<plugin>_popup_new,
   gui_<plugin>_set_graphics,
   gui_<plugin>_main_loop,
};

Here is a code sample :

void
plugin_init(void)
{
   dbg(1,"registering <your plugin>\n");
   plugin_register_gui_type("<your plugin>", <your init function>);
}

Now, here is a sample of the init function :

 static struct gui_priv *
 gui_<plugin>_new(struct navit *nav, struct gui_methods *meth, struct attr **attrs)
 {
    dbg(1,"Begin initialization of <your plugin>\n");
    struct gui_priv *this_;
        *meth=gui_<plugin>_methods;

    this_=g_new0(struct gui_priv, 1);

    // Perform initializations specific to your gui
    // ...

    // If you want to register a callback function for the vehicle, you can do it so:
    struct callback *cb=callback_new_0(callback_cast(vehicle_callback_handler));

    navit_add_vehicle_cb(nav,cb);
    this_->nav=nav;

    return this_;
}

And you plugin (gui) should initialize. Now, you need somme dummy functions (for now). Thoses are requested for GTK.

static struct menu_priv *
gui_<plugin>_toolbar_new(struct gui_priv *this_, struct menu_methods *meth)
{
   return NULL;
}

static struct statusbar_priv *
gui_<plugin>_statusbar_new(struct gui_priv *gui, struct statusbar_methods *meth)
{
   return NULL;
}

static struct menu_priv *
gui_<plugin>_popup_new(struct gui_priv *this_, struct menu_methods *meth)
{
   return NULL;
}

The following function allows to get menu entries for bookmarks

static struct menu_priv *
gui_<plugin>_menubar_new(struct gui_priv *this_, struct menu_methods *meth)
{
   *meth=menu_methods;
   return (struct menu_priv *) 1;
}

The plugin main()

And, last but not least :

static int gui_run_main_loop(struct gui_priv *this_)
{
       // Whatever needs to be done right before beginning the navigation

       // Define your viewport
   struct map_selection sel;

   memset(&sel, 0, sizeof(sel));
   sel.u.c_rect.rl.x=800;
   sel.u.c_rect.rl.y=600;

   transform_set_screen_selection(navit_get_trans(this_->nav), &sel);


   navit_draw(this_->nav);

       // Register the callback to handle navigation instructions updates
   struct navigation *navig;
   navig=navit_get_navigation(navit);

   navigation_register_callback(navig,
       attr_navigation_long,
       callback_new_0((void (*)())update_roadbook)
   );

   timeout = g_timeout_source_new(100);
   g_source_set_callback(timeout, gui_timeout_cb, NULL, NULL);
   g_source_attach(timeout, NULL);
   while (!must_quit)
   {
       //Poll event, process them

       // Call update of gps
       g_main_context_iteration (NULL, TRUE);

       // Any other task you may need

       }
       g_source_destroy(timeout);

}