GUI with Nifty GUI - jMonkeyEngine 3.0 - page 296

11. We add <useControls filename="nifty-default-con-
trols.xml" /> to include access to basic nifty controls such as buttons, and
we should add another <useControls> tag for our options menu. These
should also be added before the <screen> element.
Now, we can start looking at the Controller code for this. Perform the following five
steps to do this:
1. We should define a class that implements the ScreenController interface,
which will become the link between the GUI and the code. We can make it ab-
stract and call it NiftyController .
2. It should have two protected fields, namely, Nifty nifty and Screen
screen , which will be set from the values provided in the bind method.
3. We also need a Boolean field called optionsMenuVisible .
4. We need to add methods for each of the methods specified in the option-
sMenu.xml file, and toggleOptionsMenu() should either show or hide the
menu depending on whether optionsMenuVisible is true or not. A handy
way to get hold of an element is by using the following code:
nifty.getCurrentScreen().findElementByName("options");
5. Then, we can call either hide() or show() on the element to control visibility.
Normally, the application is shut down when Esc is pressed. Let's make the options menu
handle this instead; this consists of the following four steps:
1. Start by deleting the related mapping by adding the following line to the
NiftyAppState initialization method:
app.getInputManager().deleteMapping(SimpleApplication.INPUT_MAPPING_EXIT);
2. Now, we need to add our own mapping for the Esc key, as shown in the following
code:
app.getInputManager().addMapping("TOGGLE_OPTIONS",
new KeyTrigger(KeyInput.KEY_ESCAPE));
app.getInputManager().addListener(this,
"TOGGLE_OPTIONS");