package e4s.tutorial;

import e4s.html.*;
import e4s.servlet.E4ModuleImplementation;

/**
 * E4JavaScript and event-handler examples. Java-Scripts can be used wherever required,
 * Event-Handlers are "bound" to their base types, e.g. has the E4EventHandlerBODY 
 * functionality for bindings with onLoad() or onUnLoad(). Scripts as well as
 * event handlers can either have an explicit name or they get assigned an 
 * generic name. Scripts are collected throught the object-tag chain within
 * the HTML output (except Ajax, it always starts on HTML level) and included 
 * in the header section of the HTML file. It is also possible to use referenced
 * scripts (stored outside as .js file), but the elegance is the possibility
 * to include certain topics in the script, for example a localized text message.
 *
 * {@tutorial Example_E4JavaScript}
 */
public class Example_JavaScript extends E4ModuleImplementation
{
	public static E4Method start = null;
	
	public void start(HTML html)
	{
		BODY body = html.BODY();
		
		body.Message(E4Message.INFO, "Java-Script handling");
		
      // This is an "unnamed" script which is implementes as E4EventHandler, 
      // we can execute but not reference later on it. The handler will
      // be added explicit to the body element
		E4EventHandlerBODY loading = new E4EventHandlerBODY(E4EventHandlerBODY._EVENT_ONLOAD);
		loading.appendln("function " + loading.getName() + "()");
		loading.appendln("{");
		loading.appendln("   alert('This unnamed script was called on loading the page');");
		loading.appendln("}");
		
		body.setEventHandler(loading);

      // This is an "unnamed" script and allready associated with an onLoad() event in 
      // the body tag.
      E4EventHandlerBODY exit = body.onUnLoad();
      exit.appendln("function " + exit.getName() + "()");
      exit.appendln("{");
      exit.appendln("   alert('So long..');");
      exit.appendln("}");
     
		body.P();
		
      // this is a named script
      E4JavaScript js = new E4JavaScript("myScript");
      js.appendln("function " + js.getName() + "(txt)");
      js.appendln("{");
      js.appendln("   alert(txt);");
      js.appendln("}");

      // don't forget to add it explicitly
      body.addScript(js);
      
		E4EventHandlerA onClick = new E4EventHandlerA(E4EventHandlerA._EVENT_ONCLICK);
      onClick.setParam("on the text");
      
		onClick.appendln("function " + onClick.getName() + "(x)");
		onClick.appendln("{");
		onClick.appendln("   alert('You clicked on ' + x);");
		onClick.appendln("}");
  
		A href = body.A(onClick);
		href.println("Click here");
		
		body.P();
		
      // this is an unnamed script
      E4JavaScript butterfly = new E4JavaScript();
      butterfly.appendln("function " + js.getName() + "(txt)");
      butterfly.appendln("{");
      butterfly.appendln("   alert('you clicked the butterfly');");
      butterfly.appendln("}");

      IMG img = body.IMG("images/tutorial/Example_A/butterfly01.jpg");
	   img.setScript((E4EventHandler_Intf)onClick);
	}
	
}