add vala example

examples/example.vala

+/**
+ * I don't know vala, so this is as much as I can give you for an example.
+ *
+ * This demo allows you to connect the output socket to the input and receive
+ * an event which will change the label of the input node.
+ *
+ * The cast of to GtkNodes.NodeSocket seems necessary, because vala does not
+ * consider the socket_connect signal to be part of the socket's signals if it
+ * is returned as a GtkWidget on item_add() (which is done intentionally).
+ * 
+ * Compile with 'valac --pkg gtknodes example.vala' with the library installed.
+ * There is no makefile integration for now, sorry.
+ */
+
+
+using Gtk;
+using GtkNodes;
+
+
+int main (string[] args)
+{
+	Gtk.init (ref args);
+
+	var window = new Window ();
+	window.title = "Nodes Demo";
+	window.border_width = 10;
+	window.window_position = WindowPosition.CENTER;
+	window.set_default_size (300, 300);
+	window.destroy.connect (Gtk.main_quit);
+
+	var node_view = new GtkNodes.NodeView();
+	var node = new GtkNodes.Node();
+
+	node.set_label("Demo");
+
+	var ilbl = new Gtk.Label("Input");
+	ilbl.set_xalign(0.0f);
+
+	unowned var input = (GtkNodes.NodeSocket) node.item_add(ilbl, GtkNodes.NodeSocketIO.SINK);
+
+
+    	input.socket_connect.connect (() => {
+		ilbl.label = "connected";
+	});
+
+	input.socket_disconnect.connect (() => {
+		ilbl.label = "disconnected";
+	});
+
+
+	var olbl = new Gtk.Label("Output");
+	olbl.set_xalign(1.0f);
+	node.item_add(olbl, GtkNodes.NodeSocketIO.SOURCE);
+
+
+	node_view.add(node);
+	window.add(node_view);
+	window.show_all();
+
+	Gtk.main();
+	return 0;
+}
+
+