BnnWidget

import javax.annotation.Nonnull;

import net.teamfruit.bnnwidget.WBase;
import net.teamfruit.bnnwidget.WEvent;
import net.teamfruit.bnnwidget.WFrame;
import net.teamfruit.bnnwidget.WPanel;
import net.teamfruit.bnnwidget.WRenderer;
import net.teamfruit.bnnwidget.motion.Easings;
import net.teamfruit.bnnwidget.position.Area;
import net.teamfruit.bnnwidget.position.Point;
import net.teamfruit.bnnwidget.position.R;
import net.teamfruit.bnnwidget.render.OpenGL;
import net.teamfruit.bnnwidget.var.V;
import net.teamfruit.bnnwidget.var.VMotion;

// your main gui extends "WFrame"
public class MyGui extends WFrame {
	// init widgets in "initWidget"
	@Override
	protected void initWidget() {
		// add your panel extends "WPanel"
		add(new WPanel(new R()) {
			@Override
			protected void initWidget() {
				// "R" is a class that relatively expresses an area.
				add(new WBase(new R()) {
					// "VMotion" is a constantly changing value depending on the specified animation.
					VMotion m = V.pm(0);

					@Override
					public void draw(final @Nonnull WEvent ev, final @Nonnull Area pgp, final @Nonnull Point p, final float frame, final float opacity) {
						// Let's prepare before rendering with "WRenderer.startShape()"
						WRenderer.startShape();
						// BnnWidget provides a GL wrapper that absorbs differences in Minecraft versions.
						// The value of the "V" class is retrieved by get () every time.
						OpenGL.glColor4f(0f, 0f, 0f, this.m.get());
						// "WGui" has drawing methods that can be specified in detail with a float value.
						draw(getGuiPosition(pgp));
					}

					private boolean mouseinside;

					@Override
					public void update(final @Nonnull WEvent ev, final @Nonnull Area pgp, final @Nonnull Point p) {
						// The area of the parent widget becomes get Area of the child widget by getGuiPosition.
						final Area a = getGuiPosition(pgp);
						// PointInside determines if the cursor is over the widget
						if (a.pointInside(p)) {
							if (!this.mouseinside) {
								this.mouseinside = true;
								// Add animation and start it. Release the queue with stop.
								this.m.stop().add(Easings.easeLinear.move(.2f, 0f)).start();
							}
						} else if (this.mouseinside) {
							this.mouseinside = false;
							this.m.stop().add(Easings.easeLinear.move(.2f, .5f)).start();
						}
						super.update(ev, pgp, p);
					}

					// It is called when the GUI is closed. If you want to add closing animation, return false and let's wait.
					@Override
					public boolean onCloseRequest() {
						this.m.stop().add(Easings.easeLinear.move(.25f, 0f)).start();
						return false;
					}

					// The GUI will not exit until it returns true. Let's see if the animation has ended with isFinished.
					@Override
					public boolean onClosing(final @Nonnull WEvent ev, final @Nonnull Area pgp, final @Nonnull Point mouse) {
						return this.m.isFinished();
					}
				});
			}
		});
	}
}