Canvas embedded in Swing application renders at wrong scale on HiDPI

I am trying to embed JMonkeyEngine into a Swing application and noticed the Canvas is rendering at a different scale on HiDPI displays, the screenshot below is on a 200% scale display. I set a custom background color on the canvas to make sure it has the correct dimensions.

I combined the TetsGltfLoading class with some sample code for embedding the canvas:

package nl.rp.ddd.jme;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;

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

import com.jme3.system.AppSettings;
import com.jme3.system.JmeCanvasContext;

public class JmeTests {


	public JmeTests() {

		final JFrame frame = new JFrame();
		frame.setTitle("JME 3 Tests");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(800, 600);

		AppSettings settings = new AppSettings(true);
		settings.setWidth(800);
		settings.setHeight(600);
		settings.setVSync(true);

		TestGltfLoading canvasApplication = new TestGltfLoading();
		canvasApplication.setSettings(settings);
		canvasApplication.setDisplayStatView(false);
		canvasApplication.setDisplayFps(false);
		canvasApplication.createCanvas();
		JmeCanvasContext ctx = (JmeCanvasContext) canvasApplication.getContext();
		ctx.setSystemListener(canvasApplication);
		Dimension dim = new Dimension(800, 600);
		ctx.getCanvas().setPreferredSize(dim);
		ctx.getCanvas().setBackground(new Color(50, 50, 100));

		frame.getContentPane().setLayout(new BorderLayout());
		frame.getContentPane().add(ctx.getCanvas(), BorderLayout.CENTER);

		frame.pack();
		frame.setLocationRelativeTo(null);
		frame.setVisible(true);

	}

	public static void main(String[] args) {
		System.setProperty("org.lwjgl.opengl.Display.enableHighDPI", "true");
		SwingUtilities.invokeLater(new Runnable() {

			@Override
			public void run() {
				new JmeTests();
			}
		});
	}

}

I tested this with 3.3.2-stable, jme3-lwjgl (embedding a canvas failed with jme3-lwjgl3), java 10 and java 11 runtimes.

[remcopoelstra]

I managed to work around it for now by resizing the canvas myself (zooming in on the scene in the upper left corner), for this I override doLayout() of the parent container:

@Override
public void doLayout() {
	if (canvas != null && scale != null) {
		canvas.setBounds(0, 0, (int)(getWidth() * scale), (int)(getHeight() * scale));
	} else {
		super.doLayout();
	}
}

This does have some issues though, overlay text is rendered at wrong scale for example. I wouldn’t consider this workaround a solution to the problem.

I also did some experimenting with embedding a canvas with lwjgl3 (because I would prefer to use this instead of lwjgl2). I was able to embed a canvas on Windows with glfwAttachWin32Window() but I still have to try to get keyboard/mouse input working correctly. See this issue for more info on attaching glfw to an existing handle: https://github.com/glfw/glfw/issues/25

[glowlux]

This seems related… solution looks good. https://forum.jogamp.org/GLcanvas-vs-NEWT-on-Hi-DPI-Screens-tp4041191p4041642.html

I think returning scaled sizes from the getHeight() and getWidth() methods of the canvas is better and seems to break less things. Modified LwjglCanvas.java

Not submitting this as change though, because I’m unsure if this workaround breaks anything else…