Using Processing Core Library like a console application, no window

Processing
1

Hello, I’d like to use the processing core library, however, I don’t actually want to use the processing window or draw function at all. I’m using processing because the PImage class and some other utilities are very useful, but this is a console application and I don’t need any of the other features. I’ve got a class that extends PApplet, and its constructor calls sketchPath() and passes the path of the current running jar so that I can call loadImage() without calling setup() so a window doesn’t have to be created. This works almost perfectly, however, I’m encounter issues when running headless on Linux server, and I understand why, I just don’t know what to change to disable all the display type stuff. This is the error:

Exception in thread "main" java.awt.AWTError: Can't connect to X11 window server using '0' as the value of the DISPLAY variable.
        at java.desktop/sun.awt.X11GraphicsEnvironment.initDisplay(Native Method)
        at java.desktop/sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:102)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at java.desktop/sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:61)
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Class.java:315)
        at java.desktop/java.awt.GraphicsEnvironment$LocalGE.createGE(GraphicsEnvironment.java:101)
        at java.desktop/java.awt.GraphicsEnvironment$LocalGE.<clinit>(GraphicsEnvironment.java:83)
        at java.desktop/java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:129)
        at java.desktop/sun.awt.X11.XToolkit.<clinit>(XToolkit.java:232)
        at java.base/java.lang.Class.forName0(Native Method)
        at java.base/java.lang.Class.forName(Class.java:315)
        at java.desktop/java.awt.Toolkit$2.run(Toolkit.java:588)
        at java.desktop/java.awt.Toolkit$2.run(Toolkit.java:583)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at java.desktop/java.awt.Toolkit.getDefaultToolkit(Toolkit.java:582)
        at java.desktop/javax.swing.ImageIcon.<init>(ImageIcon.java:286)
        at processing.core.PApplet.loadImage(PApplet.java:5564)
        at processing.core.PApplet.loadImage(PApplet.java:5480)
        at ImgDiff.<init>(ImgDiff.kt:9)
        at ImgDiffKt.main(ImgDiff.kt:31)
1 Like
2

Hello,

Maybe you can just use the file PImage.java in your project :

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3

I’m not sure what method are you using, but I made myself ProcessingTest.java class that has only this:

import processing.core.PImage;
import processing.core.PApplet;
public class ProcessingTest{

	public static void main(String[] args){
		PApplet thing = new PApplet();
		thing.sketchPath();
		PImage test;
		test=thing.loadImage("/home/architector4/Pictures/test.png");
	}

}

And it compiles, loads and runs just fine without X11.

If something like this doesn’t work for you, could you please provide a minimum viable example i.e. the smallest amount of code that fails with that error?

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