Naming the main JTextArea of jEdit from a BeanShell script

Question

My goal is the following: Isabelle/jEdit is an extension of jEdit for the Isabelle theorem prover. I would like to get the typeset, syntax-highlighted version of my theory files to an image file programmatically, using a shell command, as they appear on the screen.

This is a follow-up to Calling into jEdit to get a bitmap of the rendered text where an author wrote a BeanShell script to translate a JTextArea into an image file. This is the script:

import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

img = new BufferedImage(textArea.getWidth(), textArea.getHeight(), BufferedImage.TYPE_INT_ARGB);
g = img.getGraphics();
textArea.paint(g);
g.dispose();
ImageIO.write(img, "png", new File(".../textArea.png"));

and I called that from the command line

$ isabelle jedit -j "-run=textarea-snapshot.bsh" MyTheory.thy

but the BeanShell script's textArea is undefined so I got an error.

So I should get the main JTextArea of jEdit to make this work.

As far as I understand it is created at

https://github.com/albfan/jEdit/blob/master/org/gjt/sp/jedit/gui/RegisterViewer.java#L78

contentTextArea = new JTextArea(10,20);

but it is not clear whether I can access it from a BeanShell script without modifying jEdit's code.

Could someone with jEdit experience answer how I could name this contentTextArea from my BeanShell script? Or, how could I solve my Original Goal?

It would really help us to help you if you [tell people your actual goal](https://technojeeves.com/index.php/aliasjava1/15-smart-questions) — g00se, Aug 14 '23 at 15:56
Why not just execute a screenshot app set to capture the active window? — g00se, Aug 14 '23 at 16:31
Because I want to do this programmatically, to create a document preparation system. — Gergely, Aug 15 '23 at 09:28

score 1 · Accepted Answer · answered Aug 15 '23 at 15:32

The BeanShell script I gave you in that linked question was to take an image of an already running and existing jEdit instance. There textArea is exactly the way to access the text area.

If you run that script during a fresh startup of jEdit, it is executed too early and the text area does not yet exist.

If you want to do it like that, you need to write a more sophisticated script, that registers an EditBus component and thus can react to events like the view being activated.

Something along the lines of

import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;

EditBus.addToBus(new EBComponent() {
    public void handleMessage(EBMessage message) {
        if ((message instanceof ViewUpdate) && (message.getWhat() == ViewUpdate.ACTIVATED)) {
            EditBus.removeFromBus(this);
            textArea = message.getView().getTextArea();
            img = new BufferedImage(textArea.getWidth(), textArea.getHeight(), BufferedImage.TYPE_INT_ARGB);
            g = img.getGraphics();
            textArea.paint(g);
            g.dispose();
            ImageIO.write(img, "png", new File("textArea.png"));
        }
    }
});

Thanks indeed. Could you suggest me reading so that I could develop such things? — Gergely, Aug 16 '23 at 07:54
And yes, I tried the script, it does run and gives me an image file, but an empty one. I should look into how I can set the cursor to some point in the file and wait for the rendering to complete. — Gergely, Aug 16 '23 at 08:16
It worked for me, having the script file open in jEdit with plain jEdit. Might be that you need some adaption though depending on what Isabelle does there, yes, hence the "along the lines of". :-) For reading, you can have a look at the macro and plugin development documentation of jEdit included in the normal help and the JavaDoc. The macro is basically doing what you could also do in some plugin, same API. — Vampire, Aug 16 '23 at 15:27

Naming the main JTextArea of jEdit from a BeanShell script

1 Answers1