Hi-- I'm trying to write a GUI-based Java program from within Clojure,
and I'm using an interesting library called Piccolo2D (http://
www.piccolo2d.org). The worldwide intersection of Clojure and
Piccolo2D is probably *me*, but I'm hoping that someone here can point
me in the right direction.
I'm starting by trying to translate an existing Hello World program
into its Clojure equivalent:
------------------------------------------------
import javax.swing.JFrame;
import edu.umd.cs.piccolo.PCanvas;
import edu.umd.cs.piccolo.nodes.PText;
public class HelloWorldExample extends JFrame {
private HelloWorldExample() {
final PCanvas canvas = new PCanvas();
final PText text = new PText("Hello World");
canvas.getLayer().addChild(text);
add(canvas);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(600, 400);
setVisible(true);
}
public static void main(String[] args) {
new HelloWorldExample();
}
}
------------------------------------------------------
Here's my best attempt so far:
------------------------------------------------------
(ns piccoloHello
(:gen-class)
(:import (edu.umd.cs.piccolo PCanvas PNode PLayer)
(edu.umd.cs.piccolo.nodes PText)
(edu.umd.cs.piccolox PFrame)))
(defn create-frame
"Creates the main PFrame used by the program."
[]
(proxy [PFrame] []
(initialize []
(let [aCanvas (PCanvas.)
aFrame (PFrame. "Piccolo2D Hello World" false aCanvas)
aNode (PText. "Hello World")
aLayer (.getLayer aCanvas)]
(. aLayer .addChild aNode)))))
(defn -main []
(let [main-frame (create-frame)]
(.setVisible main-frame true)))
--------------------------------------------------------
Running it displays a window with "Piccolo2D Hello World" in the title
bar, but no text in the window's canvas. The program exits with the
following error message:
>>>>> Exception in thread "AWT-EventQueue-0"
>>>>> java.lang.IllegalArgumentException: No matching method found: .addChild
>>>>> for class edu.umd.cs.piccolo.PLayer
BTW, you probably should know that PCanvas is a subclass of
JComponent, that PLayer and PText are subclasses of PNode, and that
PLayer does not have an addChild method, but that PNode does.
POSSIBLE CAUSES: One, it's probable that I don't know what I'm doing
and I have the wrong syntax for using proxy to subclass PFrame. Two,
my suspicion is I need to do something special to invoke PNode's
addChild method on aLayer, and I don't know what that is. I found
proxy-super as a Clojure function, but I couldn't find a way to use it
that helped.
Any educated guesses? Thanks.
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