How to use controllers in Nifty

codex · July 23, 2021, 1:05am

I’m having trouble understanding how controllers work in Nifty. I tried to get my Player class to modify the gui, but I couldn’t get it and I can’t tell what went wrong.
Could someone please explain how to use controllers?

Note: I’ve already looked at most of the relevant wiki here. I followed whatever I could, but I couldn’t understand exactly what was going on in some parts.

sgold · July 23, 2021, 6:00am

There’s more than one way to do use Nifty controllers in JME. What I usually do is to create an appstate for each screen. A screen is displayed if and only if its appstate is enabled. Most of the relevant code is here:

github.com

stephengold/jme3-utilities/blob/2d5dd8a077daa94bb2de52bbcaaf2fea507c86ce/nifty/src/main/java/jme3utilities/nifty/BasicScreenController.java#L48

    
      
          import de.lessvoid.nifty.screen.ScreenController;
          import java.util.ArrayList;
          import java.util.Collection;
          import java.util.List;
          import java.util.logging.Level;
          import java.util.logging.Logger;
          import jme3utilities.MyString;
          import jme3utilities.Validate;
          import jme3utilities.ui.InputMode;
          
          
/**
           * A GuiAppState to control a Nifty screen. A screen is displayed if and only if
           * its controller is enabled. No more than one screen can be enabled/displayed
           * at a time.
           * <p>
           * Each instance is disabled at creation, with an option for automatic enabling
           * during initialization.
           *
           * @author Stephen Gold sgold@sonic.net
           */
          public class BasicScreenController

codex · July 23, 2021, 3:28pm

Ok, but how do I use and implement this into my XML/Java?

sgold · July 23, 2021, 5:59pm

For each screen, create a BasicScreenController (or an instance of some class that extends it). If you’re using XML, reference the controller’s fully-qualified classname in the screen layout like so:

<nifty xmlns="http://nifty-gui.lessvoid.com/nifty-gui">
    <screen id="s1" controller="com.github.stephengold.S1Controller">
        <layer childLayout="vertical" backgroundColor="#444f">