Infomaniac is a Firefox extension for Fluidinfo.

Introduction

Infomaniac is a Firefox extension that makes it easy to follow web pages, see the info other people have stored and to add one's own info about them. The extension adds a sidebar to the browser and, as such, must be XUL-based. The sidebar contains a browser XUL element which displays a mini-object browser served from fluidinfo.com. As the user changes tabs and pages the sidebar is updated to show the relevant content.

Development and testing

Follow the instructions here to prepare a development profile and tweak some settings to get information about errors when the extension runs:

https://developer.mozilla.org/en/Setting_up_extension_development_environment

When that's done put a file in ~/.mozilla/firefox/<profile>/extensions called jid1-AiwVfZ6h5L6xsQ@jetpack with a single line containing the path to this repository. Start Firefox and hit Ctrl-Shift-f to see the extension in action:

/usr/bin/firefox -no-remote -P dev

You need to restart the browser whenever you make a change to the extension logic before it will be visible. When the browser is running install the Firebug extension.

When you use Firebug for the first time click on the little box next to "Console" to enable it. Then click on the little menu arrow beside "Console" and turn on the following options:

• Show Javascript Errors
• Show Chrome Errors
• Show Chrome Messages
• Show Stack Trace With Errors

They'll persist between browser restarts so you should only need to do this once.

Handling page and tab changes

The extension needs to detect a few several kinds of state changes and update itself to ensure that the content it displays always matches the current page:

• A new tab is opened showing the empty about:blank page.
• A new tab is opened showing a page that can be followed.
• The active tab is switched from one to another.
• The page in the active tab isn't loaded yet.
• The page in the active tab finishes loading.
• The page in the active tab is changed.
• The page in an inactive tab has changed since the last time the extension updated itself (say because of an automatic refresh or because a page was loading slowly and the user switched away while it finished).

As you can see many things can happen that must result in the extension updating its state. The way it does this is by listening for and responding to a combination of events, which are described on these pages:

• https://developer.mozilla.org/en/Code_snippets/Tabbed_browser
• https://developer.mozilla.org/en/Code_snippets/On_page_load

Setting the root URL

The root URL, used to fetch the extension content, is stored in the extensions.infomaniac.rootURL preference. Preferences are described in some detail here:

https://developer.mozilla.org/en/Code_snippets/Preferences

The default can be overridden by opening about:config and setting a new endpoint. It's quite useful to use a browser profile just for development, as described above, with the root URL set to a local instance of fluidinfo.com.

Making a new release

Create a .xpi file:

make

This will create an infomaniac.xpi file that's ready to deploy.

Further information

There are a number of resources you'll need to have on hand to understand and modify the extension:

• https://developer.mozilla.org/en/XUL_tutorial provides a nice introduction to XUL.
• https://developer.mozilla.org/en/XUL_reference provides a list of XUL elements with links to detailed API documentation for each one.
• https://developer.mozilla.org/en/Code_snippets provides a list of examples, nicely organized by topic, which are indispensable when learning how to perform basic (and not-so-basic) tasks.
• https://developer.mozilla.org/en/Extension_packaging provides instructions for making an XPI. It also has some information about how to install the extension directly and serve the file correctly from a web server.