GUI development

From Navit's Wiki
Revision as of 08:49, 29 March 2010 by Akashihi (talk | contribs) (Added gui category)
Jump to: navigation, search

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);
        
}