Add custom data (field) to sidebar widgets for later display

Question

I am building a theme that allows widgets to be dragged & dropped, essentially turning WP into a desktop-like environment where the admin controls what "apps" are available via the widget panel.

This is going reasonably well, except that it would be nice is if there were a way for the admin to store starting locations for all of the widgets (and presumably, more meta-data later)

In practical terms, this means I want 2 custom fields to appear on each widget in the admin panel, and then for there to be a hook to spit that data out when the widgets are printed on the page (in my case as some inline style values).

I am building this "desktop" using home.php

I am not sure if wordpress is actually built to do this, but it seems vaguely plausible. Any thoughts? Thanks!

Answer 1

Crude code. I have never tried this but I can get you part of the way there.

Add a field...

add_action(
  'in_widget_form', 
  function ($instance) {
    echo '<input type="text" value="c00l" />';
    return null;
  },
  1
);

And there is a hook that runs on settings update.

add_filter(
  'widget_update_callback', 
  function($instance, $new_instance, $old_instance, $this) {
    var_dump($instance, $new_instance, $old_instance, $this); die;
  },
  1,4
);

However, it looks like you need to add an option/setting to the widget before that hook will work and I don't see how to do that. I am probably missing something obvious but don't have time to do more research right now.

Reference

http://core.trac.wordpress.org/browser/trunk/src/wp-includes/widgets.php