Saving per-user or per-document preferences in a P

Question

I'm working on a Photoshop script in JavaScript using ExtendScript. My script allows some user input, and I'd like to save it between uses. That is, I'm looking for a way to save a simple string or numeric value under a particular key so that I'll be able to access it on subsequent uses of the script. Simply put, I want to save a preference for my script. How do I do that?

Even better would be to be able to save at least some preferences on a per-document basis. Is that possible? That is, can I store an arbitrary bit of data with a document?

Answer 1

For per-document prefs I suggest the use of the XMP Metadata. You can find example snippet here: http://forums.adobe.com/thread/790973. You can leverage AdobeXMPScript library to create your own namespace like it is suggested in the link by Paul Riggott.

Answer 2

You can use put/get custom options to save preference parameters that persist across Photoshop launches:

const kMyFlag = app.stringIDToTypeID( "myFlag" );
const kMyNumber = app.stringIDToTypeID( "myNumber" );
const kMySettings = "mySettings";

function saveSettings()
{
  var desc = new ActionDescriptor();
  desc.putBoolean(kMyFlag, true);
  desc.putInteger(kMyNumber, 42);

  // "true" means setting persists across Photoshop launches.
  app.putCustomOptions( kMySettings, desc, true );
}

function getSettings()
{
  var desc = app.getCustomOptions( kMySettings );
  return [desc.getBoolean( kMyFlag ), desc.getInteger( kMyNumber )];
}

Answer 3

You have some options. You can create a text file and write to it using the File object:

var prefs = new File("~/desktop/prefs.txt");
prefs.open("w"); // or "a" to append
prefs.writeln("user:lenny;favorite_color:ff6600;likes:sunsets;");

...if you wanted your preferences tied to the script itself.

If you want per-document preferences you could write a string to one of the metadata fields of the file your working on using Document.info like this (using the 'instructions' field but you could use any writable field):

var doc = app.activeDocument;
doc.info.instructions = "user:lenny;favorite_color:ff6600;likes:sunsets;";
//alert(doc.info.instructions); // see, it works!

As for how to actually format the string you could just do it like a simple config file or, if you have a complex user preferences object you could use the XML object to construct and serialize it. JSON would be great for this but there is no JSON object in Extendscript, unfortunately.