AWTGLCanvas draw on demand

DrawOnDemand.java

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ComponentAdapter;

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

import org.lwjgl.opengl.GL;
import org.lwjgl.opengl.GL11;
import org.lwjgl.opengl.awt.AWTGLCanvas;

public class DrawOnDemand {

	public static void main(String[] args) {
		AWTGLCanvas canvas = new AWTGLCanvas() {

			@Override
			public void paintGL() {
				int w = getWidth();
				int h = getHeight();
				if(w==0 || h == 0){
					return;
				}
				float aspect = (float) w / h;
				GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);
				GL11.glViewport(0, 0, w, h);
				GL11.glBegin(GL11.GL_QUADS);
				GL11.glColor3f(0.4f, 0.6f, 0.8f);
				GL11.glVertex2f(-0.75f / aspect, 0.0f);
				GL11.glVertex2f(0, -0.75f);
				GL11.glVertex2f(+0.75f / aspect, 0);
				GL11.glVertex2f(0, +0.75f);
				GL11.glEnd();
				swapBuffers();
			}

			@Override
			public void initGL() {
				GL.createCapabilities();
			}

			@Override
			public void repaint() {
				if(SwingUtilities.isEventDispatchThread()){
					render();
				} else {
					SwingUtilities.invokeLater(()->render());
				}
			}

			/**
			 * NOOP - this canvas is painted using OpenGL through the {@link #render()} method.
			 */
			 @Override
			 public final void paint(Graphics g) {
				 // don't modify the graphics object
			 }

			 /**
			  * NOOP - this canvas is painted using OpenGL through the {@link #render()} method.
			  */
			 @Override
			 public final void paintAll(Graphics g) {
				 // don't modify the graphics object
			 }

			 /**
			  * NOOP - this canvas is painted using OpenGL through the {@link #render()} method.
			  */
			 @Override
			 public final void update(Graphics g) {
				 // don't modify the graphics object
			 }

		};

		JFrame frame = new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().add(canvas);
		canvas.setPreferredSize(new Dimension(200, 200));
		canvas.addComponentListener(new ComponentAdapter() {
			public void componentResized(java.awt.event.ComponentEvent e) {
				canvas.repaint();
			};
		});

		SwingUtilities.invokeLater(()->{
			frame.pack();
			frame.setVisible(true);
		});
	}

}