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BetterPonymotes is an emote addon to serve the pony subreddits. It currently supports Chrome (including other browsers that support Chrome extensions, like Opera, Chromium, and Vivaldi), Firefox, Firefox Mobile, and Safari.

Its data is maintained as a set of files by the addon maintainer, and compiled into compact representations for use by the addon at build time in the form of a large, executable JS file. Its code is split between maintenance tools on the backend (mostly Python) and JS that runs in the browser.


First off, there are some files and directories that aren't in the git repo but need to exist.


The PEM file is a private, unencrypted RSA key. It looks like this:

[lots of base64 stuff]

The Makefile expects it to be available in the root of the project directory, but you can edit it if you like. The only thing that matters is that you NEVER expose it and NEVER lose it. Update security depends on it.

BPM assumes a POSIX environment, with standard utilities like cp, rm, make, sed, etc. available on your PATH. This means that developing on Windows is not currently supported. (But feel free to try to get the build working on Windows if you want.)

You'll also need the following tools:

  • Python 3. Most of the scripts used for building and maintaining BPM are written in python. You'll need python installed and on your PATH with the name python3 in order to build BPM. (Many Linux distributions already have this by default.)

  • Python 2. The script BPM uses to tag emotes still requires Python 2, so you'll need Python 2 installed and on your PATH with the name python2 in order to tag emotes in BPM. (Many Linux distributions already have this by default.)

  • zip, a command line utility for creating zip-formatted archives. Needs to be on your PATH. If you don't already have it, it can probably be installed using your system's package manager. (E.g. sudo apt-get install zip on Ubuntu)

  • The Firefox Addon SDK. It comes in a zip file with a bin/activate shell script. Source it to add its bin/ to your $PATH, because you need the cfx tool.

  • uhura. It's a little perl script used to sign the Firefox XPI's. It needs to be on $PATH. I'm not sure exactly where I got it, and installing it is a pain, since it depends on some CPAN modules. I forget which.

  • apng2gif. A tool to convert APNG files to GIF format. Needs to be on your PATH in order to build BPM.

Repository Structure

# Animote support
animotes/               Converted GIF cache (not kept in repo due to size)           Script to maintain animotes/ and build/gif-animotes.css

# Scripts and code                All-around emote update tool. Handles downloading
                        new stylesheets.
bplib/                  Python support library         CSS compressor              CSS parsing          Emote extraction             A JSON dumper with better output formatting          In-memory representation of all the emote data, as
                        well as code to load/save it all.          "Emote resolution", that is, resolves conflicts and
                        does the majority of the work in dumping data.             Tool to exports all emote data to JSON. DinsFire64
                        uses this data to maintain his Reddit News emote pack.            Extracts emote data from minified CSS files.
                        minified-css/ -> emotes/                Builds the addon data files.
                        emotes/ + tags/ + data/ -> build/bpm-resources.js

# Build process
build/                  Build directory (not in repo)
Makefile                Pretty much the whole build process. Its main target
                        rebuilds all data files and addons.
web/                    Most actual site files.
    index.html          Main page.
www/                    A complete copy of the site. Synced to
                        Firefox update manifest file.
    *.xpi               Hosted addon files.

# Addon directories
addon/                  All common code and static data files (CSS).
    bpm-*.js            Main script.
    pref-setup.js       All-around utility and framework for backend scripts.
                        Does a lot more than just preferences.
    bpmotes.css         Misc CSS used by the addon, and some things that can't
                        be put anywhere else.
    combiners-nsfw.css  NSFW components of r/mylittlecombiners that aren't emotes.
    extracss-pure.css   Chaos script. Most fancy emote flags are here.
    extracss-webkit.css This CSS is specific to WebKit/Blink and not
                        compatible between browsers.
    options.html        Options page.
    options.js          Options page code.
    options.css         Options page CSS.
    bootstrap.css       Bootstrap. Used on the options page.
    cr-background.html  Chrome background page. Holds prefs and things for the addon.
    cr-background.js    Chrome background code.
    cr-manifest.json    Chrome addon manifest.
    fx-main.js          Firefox backend script.
    fx-package.json     Firefox addon manifest.

# Data files
data/                   Misc data files you need to maintain.
    rules.yaml          Main controlling data file for the addon.
    tags.yaml           Tag rules.
    icons.svg           Original SVG for the icons BPM has. Encoded into CSS manually.

# Cached data
emotes/                 Extracted emote cache. All of these can be regenerated.
minified-css/           The minified CSS that Reddit serves up. These are what get parsed for emotes.
source-css/             Unminified CSS, pulled from /about/stylesheet. Useful for reading.
                        Note that the script can't pull down files in NSFW
                        subreddits, so those are missing.

# Tag maintainence
tags/                   Tag data.               A small Flask-based webapp used to tag emotes.            Verifies the tag data for most kinds of inconsistencies. Run this after editing, always.
tagapp-static/          Static data for the emote tagging webapp.
    css/tagapp.css      CSS
    js/tagger.js        JavaScript for the UI
templates/              Templates for the emote tagger.

All of this will be explained in detail further on.

Browser Addon Structure

Most addon API's have the same basic structure- there's a background script that runs on its own, and content scripts that run in the pages. The former must obviously be written to the specific browser, but the latter is largely independent except where it has to communicate with the backend.

Firefox's background script is addon/fx-main.js. Chrome has addon/cr-background.html, and Safari has addon/sf-background.html. As these scripts share a large amount of functionality, most of that is now held in addon/pref-setup.js.

The backend is chiefly responsible for storing and managing preferences, applying the necessary files to pages (JS and CSS), and maintaining the custom CSS cache. Custom CSS is easily the most complex thing it does.

bpm-browser.js is dedicated to abstracting over the differences between browser API's and communication.

Development Process

Most of the addon proper in the content script split up between the addon/bpm-*.js files. Most new features can be implemented here without touching anything else.

Changing DEV_MODE in bpm-header.js enables a bunch of extra logging, which may help if you're getting crashes or strange behavior. Remember to disable it before release.

Changes to preferences require editing addon/pref-setup.js and the options page.

Changes involving the data backend are too complicated to go over here.

Stylesheets, Emote Data, and Compilation

Stylesheets are stored and cached in two forms - source and minified. The reason is that Reddit, by default, serves up only the minified form, and while this is enough to extract emote data, it's very difficult to read, which is very often necessary when maintaining the emote cache. The source CSS, however, has no image URLs. Since those can change freely, the only way to reliably know when emotes change is to reparse the minified CSS.

The tool is responsible for updating stylesheet files. Its chief commands are:

  • update: redownloads all stylesheets
  • extract/extractall: runs the emote extraction tool on particular subreddits
  • diff: runs git diff | kompare for convenient visual browsing.
  • commit: runs git commit -m [...] with a standard message.

Emote data is stored in JSON form under emotes/, one line per emote. This makes it quite conveniently diffable and greppable.

The tool (run by make automatically) reads the data/rules.yaml file for instructions, loads all emote and tag data, and compiles it into a set of JS data files (build/bpm-resources.js) and CSS (build/emote-classes.css). These are used by the addon directly.

Tagging Emotes

After updating the emote cache, any new or changed emotes need to be tagged appropriately. The ./ script starts a web server on localhost:5000, running a webapp for this purpose. It's not too difficult to figure out how to use, but tag data has a specific structure that should be respected.

[Small warning: the tagapp is one of the few Python scripts in the project that runs under Python 2 (the rest is Python 3). It uses bplib/ code, however, and there are some lingering unicode/json incompatibilities and bugs as a result. In a nutshell, running the script seems to work fine on its own, but not from a shell that has been "activated" with the Addon SDK. It seems to change the Python environment.]

Generally, most tags fall under others in a loose, informal hierarchy. These can be reviewed in data/tags.yaml.

Every emote must fall under at least one RootTag. ExclusiveTags can never be used with any other tags (except as mentioned). HiddenTags are removed from the data set before building the addon files. TagAliases generate additional records in the data files, so that searching on those tags will work properly. TagImplications essentially makes a given tag also apply several others - this is how the hierarchy is built. Note that this is not recursive.

Every emote has exactly one primary name with all of its tags. Other names for the same emote must be tagged as +v (for "variant"). will match them up automatically, copy tags around, and the tag search code in the addon uses this information to hide variants (in actuality, replacing them with their base name).

The formatting (colors and fonts) psuedo-emotes are tagged +formatting. Emotes that don't work right are tagged +broken, any emotes that should be removed from the final product are tagged +remove. +nsfw is obvious and +q (short for +questionable) is slightly less so.

Run ./ after editing tags to guard against typos and certain classes of mistakes. Some warnings are known oddities that the script isn't capable of recognizing; ignore those.

APNG -> GIF Conversion

Assuming all animotes are tagged with +animote, run ./ to download and convert all of them. This process requires apng2gif to be on $PATH, and it will spit out GIFs to animotes/, which must be uploaded to the host site. It also generates build/gif-animotes.css, which is the override sheet used by Chrome.

Updates and Version Numbers

After updating the CSS and tags, run commit to record it all, and either run manually or make to regenerate the emote data files. This process is heavily controlled by data/rules.yaml, which lists:

  • The subreddits currently in the addon (note that update doesn't actually respect this)
  • Subreddits to disregard PONYSCRIPT-IGNORE on (needed when they incorrectly put custom emotes in this block)
  • Custom tweaks to the emote set (as emotes/ is never modified directly)
  • Conflict resolution rules, by subreddit (e.g. r/aaaa > r/bbbb) and by individual emote.
  • Explicit matchups for +v emotes that the code can't autodetect.

The version number is at the top of the Makefile, and is used by make to automatically update the version numbers every browser addon that BPM supports.

When everything is updated, running make is sufficient to rebuild all packages.

Release Process

To release BPM:

  1. Run make to rebuild all packages.
  2. Upload build/ to the Chrome webstore.
  3. Upload build/betterponymotes.xpi to for package signing. Download the output file to build/.
  4. Run make www to rebuild the website.
  5. Run make sync to synchronize with, including the Firefox package.
  6. Make update threads, message /u/TwilightShadow1, /u/DinsFire64 and other interested third parties.









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