lemur-ui

name	lemur-ui
description	Build user interfaces using Lemur UI framework. Use when creating menus, HUD elements, buttons, labels, or other GUI components.

Lemur UI Framework

Lemur is the UI framework for building game interfaces. Documentation from official wiki.

Initialization (from Wiki)

// In simpleInitApp() or app initialization
GuiGlobals.initialize(this);

// Load the 'glass' style (requires Groovy dependency)
BaseStyles.loadGlassStyle();

// Set 'glass' as default style
GuiGlobals.getInstance().getStyles().setDefaultStyle("glass");

Positioning and Size (from Wiki)

Important: GUI elements are positioned by their upper left corner and grow down and right. This is a compromise between OpenGL (0,0 at lower left) and traditional UI (0,0 at upper left).

// Put window at upper area - elements grow DOWN from this point
myWindow.setLocalTranslation(300, 300, 0);

Class Hierarchy (from Wiki)

Spatial
  └── Panel (base: background, border, insets, alpha)
        ├── Container (adds layout support)
        └── Label (adds text, icon, font, color)
              └── Button (adds click commands, highlight)

Base GUI Elements

Panel Properties

• background: Background component (QuadComponent)
• border: Border component (underneath background)
• insets: Insets3f - space around element within parent (like CSS margin)
• alpha: Fade in/out entire hierarchy

Container

// Create with default SpringGridLayout
Container myWindow = new Container();
guiNode.attachChild(myWindow);

// Or with specific layout
Container c = new Container(new BorderLayout());

Label Properties

• text: Display text
• icon: Icon component
• font, fontSize: Text rendering
• textVAlignment: VAlignment.Top/Bottom/Center
• textHAlignment: HAlignment.Left/Right/Center
• color: Text color
• shadowColor, shadowOffset: Text shadow

Label label = new Label("Hello, World.");
label.setFontSize(16);
label.setColor(ColorRGBA.White);

Button

Extends Label with click support.

Button clickMe = myWindow.addChild(new Button("Click Me"));
clickMe.addClickCommands(new Command<Button>() {
    @Override
    public void execute(Button source) {
        System.out.println("Clicked!");
    }
});

// Or with lambda
clickMe.addClickCommands(source -> System.out.println("Clicked!"));

Button Actions: ButtonAction.Down, Up, Click, HighlightOn, HighlightOff

TextField Properties

• text: Entered text value
• singleLine: true (default) or false for multiline
• preferredWidth: Width hint for layouts

TextField field = new TextField("default");
String value = field.getText();

Layouts (from Wiki)

SpringGridLayout (default)

Row-major by default. Children added to grid cells.

Container c = new Container();  // SpringGridLayout by default

// Explicit grid positions (row, column)
c.addChild(new Label("Foo"), 0, 0);
c.addChild(new Label("Bar"), 1, 0);

// Shortcut - auto-increments row
c.addChild(new Label("Foo"));
c.addChild(new Label("Bar"));

// Two-column layout - specify column only
c.addChild(new Label("Name:"));
c.addChild(new TextField("value"), 1);  // column 1
c.addChild(new Label("Age:"));
c.addChild(new TextField("25"), 1);     // column 1

BorderLayout

Container c = new Container(new BorderLayout());
c.addChild(new Label("Top"), Position.North);
c.addChild(new Label("Bottom"), Position.South);
c.addChild(new Label("Center"), Position.Center);
c.addChild(new Label("Left"), Position.West);
c.addChild(new Label("Right"), Position.East);

Composite Elements (from Wiki)

Slider

Slider slider = new Slider();  // x-axis default
slider.setDelta(1);  // increment amount
double value = slider.getModel().getValue();

ProgressBar

ProgressBar progress = new ProgressBar();
progress.setProgressPercent(0.5);  // 50%
progress.setMessage("Loading...");

ListBox (proto)

ListBox<String> listBox = new ListBox<>();
listBox.getModel().add("Item 1");
listBox.getModel().add("Item 2");

OptionPanelState (proto)

// Add to state manager once
stateManager.attach(new OptionPanelState());

// Show modal dialogs
getState(OptionPanelState.class).show("Title", "Message");
getState(OptionPanelState.class).showError("Error", "Something went wrong");

Styling (from Wiki)

Element IDs

Define style hierarchy: container.contained.contained

// Create with ElementId
Container window = new Container(new ElementId("mywindow"));
Button btn = new Button("Click", new ElementId("mywindow.button"));

Selectors (Groovy style language)

// Style all elements of 'glass' style
selector('glass') {
    fontSize = 20
}

// Style specific element ID
selector('button', 'glass') {
    color = color(0.5, 0.75, 0.75, 0.85)
    background = new QuadBackgroundComponent(color(0, 1, 0, 1))
}

// Containment selector - only buttons inside sliders
selector('slider', 'button', 'glass') {
    fontSize = 10
}

Style in Code

Styles styles = GuiGlobals.getInstance().getStyles();
Attributes attrs = styles.getSelector("button", "glass");
attrs.set("color", new ColorRGBA(0.5f, 0.75f, 0.75f, 0.85f));
attrs.set("fontSize", 14);

Project-Specific Patterns

ActionButton with CallMethodAction

import com.simsilica.lemur.ActionButton;
import com.simsilica.lemur.CallMethodAction;

ActionButton btn = new ActionButton(
    new CallMethodAction("Button Text", this, "methodName")
);
btn.setInsets(new Insets3f(5, 10, 5, 10));
window.addChild(btn);

// Method called when clicked
protected void methodName() {
    log.info("Button clicked");
}

Menu State Pattern

public class MainMenuState extends BaseAppState {
    private Container mainWindow;

    @Override
    protected void initialize(Application app) {
        mainWindow = new Container();
        // Build UI...
    }

    @Override
    protected void onEnable() {
        ((SimpleApplication) getApplication()).getGuiNode().attachChild(mainWindow);
        GuiGlobals.getInstance().requestCursorEnabled(this);
    }

    @Override
    protected void onDisable() {
        mainWindow.removeFromParent();
        GuiGlobals.getInstance().releaseCursorEnabled(this);
    }
}

Project Assets

• Styles in infinity/assets/Interface/