There's been some previous work with integrating scripting support of the processing API.
http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Integrate;action=display;num=1187581621

http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Integrate;action=display;num=1187597413

I took the approach of integrating the JSR 223(https://scripting.dev.java.net/) scripting engines into processing. Which will allow you to write processing applications in a whole variety of languages (javascript, perl, python, scheme, ruby, etc).


I did a quick write-up here:
http://eventhorizongames.com/wiki/doku.php?id=articles:processing:scripting:start

You can try an example of a script enabled Processing applet that lets yo u modify and reinterpret the code from a webpage (this could easily be extended to a full featured online processing sketchbook IDE).
http://jddaniels.googlecode.com/svn/trunk/processing-scripting/dist/index.html

Ohh you just want a simple way to interact with a parameter in your sketch.

Check out some of the Interaction examples that show how to modify your sketch dynamically based on user input from the mouse.

Also there's an easy to use GUI toolkit called Interfascia (there are probably many more) for processing that lets you use textfield's that you can have interact with your sketch.
http://superstable.net/interfascia/download.htm

Here's an example that lets you type in the radius of a circle that will be drawn:

http://ddaniels.net/ddanielsblog/processing/GUISketch/


Code:

import interfascia.*;

GUIController c;
IFTextField radiusTxt;
IFLabel label1;
float radius = 30;

DecimalFormat format;

void setup() {
  size(400, 400);
  background(200);
  
  c = new GUIController(this);

  label1 = new IFLabel("radius  = ", 25, 1);
  radiusTxt = new IFTextField("radius", 75, 1, 50, radius+"");
  
  radiusTxt.addActionListener(this);
  
  c.add(label1);
  c.add(radiusTxt);
  
  format = new DecimalFormat();
  format.setMaximumFractionDigits(2);
}

void draw() {
  background(200);
  if(radius>0) {
	ellipse(width/2, height/2, radius, radius);
  }
}

void actionPerformed(GUIEvent e) {
  float temp;
  if (e.getMessage().equals("Modified")) {
    if (e.getSource() == radiusTxt) {
	try {
	  radius = Float.parseFloat(radiusTxt.getValue());
	} catch (Exception e2) { }
    } 
  }
}

 

So you want some way to generate an array of PImage[] using a script and then pushing that into your processing sketch to be displayed and scrolled through in the video editor.

You could pretty easily delegate a part of your sketch to a script. For example you could define a generateData() function that would generate an array of PImage[], and that function would actually use the text in a textfield to interpret a script which would return that PImage[].



Code:

PImage[] generateData() {
 return (Pimage[])invoke("generateData");
}

Object invoke(String methodName){ 
  //This is where you "compile" or evaluate your script from the text box
  //e.g.
  String scriptContents = textField.getValue();
  ScriptEngine jsengine;
  ScriptEngineManager manager = new ScriptEngineManager();
  jsengine = manager.getEngineByName("JavaScript");
  //Parse the script so you can access it's functions
  jsengine.eval(scriptContents);

  Invocable invocable = (Invocable)jsengine;
  //Call the method passing in the PApplet as an argument
  //in a Object[]
  return invocable.invokeMethod(methodName, new Object[]{this});  
  
}
 

Then in Javascript you can define it as something like:
Code:

importPackage(Packages.processing.core);

function generateData(p) {
 var numFrames = 1000;
 var images;
 //Run your cellular automata logic and return the PImage array
 
//...

  return images;
 
}
 

When I get a chance I might try and prototype something like this.