pleroma/docs/docs/configuration/custom_emoji.md

Custom Emoji

Before you add your own custom emoji, check if they are available in an existing pack. See Mix.Tasks.Pleroma.Emoji for information about emoji packs.

To add custom emoji:

• Create the STATIC-DIR/emoji/ directory if it doesn't exist (STATIC-DIR is configurable, instance/static/ by default)
• Create a directory with whatever name you want (custom is a good name to show the purpose of it). This will create a local emoji pack.
• Put your .png emoji files in that directory. In case of conflicts, you can create an emoji.txt file in that directory and specify a custom shortcode using the following format: shortcode, file-path, tag1, tag2, etc. One emoji per line. Note that if you do so, you'll have to list all other emojis in the pack too.
• Either restart Akkoma or connect to the iex session Akkoma's running and run Pleroma.Emoji.reload/0 in it.

Example:

image files (in instance/static/emoji/custom): happy.png and sad.png

content of emoji.txt:

happy, /emoji/custom/happy.png, Tag1,Tag2
sad, /emoji/custom/sad.png, Tag1
foo, /emoji/custom/foo.png

The files should be PNG (APNG is okay with .png for image/png Content-type) and under 50kb for compatibility with mastodon.

Default file extentions and locations for emojis are set in config.exs. To use different locations or file-extentions, add the shortcode_globs to your secrets file (prod.secret.exs or dev.secret.exs) and edit it. Note that not all fediverse-software will show emojis with other file extentions:

config :pleroma, :emoji, shortcode_globs: ["/emoji/custom/**/*.png", "/emoji/custom/**/*.gif"]

Emoji tags (groups)

Default tags are set in config.exs. To set your own tags, copy the structure to your secrets file (prod.secret.exs or dev.secret.exs) and edit it.

config :pleroma, :emoji,
  shortcode_globs: ["/emoji/custom/**/*.png"],
  groups: [
    Finmoji: "/finmoji/128px/*-128.png",
    Custom: ["/emoji/*.png", "/emoji/custom/*.png"]
  ]

Order of the groups matters, so to override default tags just put your group on top of the list. E.g:

config :pleroma, :emoji,
  shortcode_globs: ["/emoji/custom/**/*.png"],
  groups: [
    "Finmoji special": "/finmoji/128px/a_trusted_friend-128.png", # special file
    "Cirno": "/emoji/custom/cirno*.png", # png files in /emoji/custom/ which start with `cirno`
    "Special group": "/emoji/custom/special_folder/*.png", # png files in /emoji/custom/special_folder/
    "Another group": "/emoji/custom/special_folder/*/.png", # png files in /emoji/custom/special_folder/ subfolders
    Finmoji: "/finmoji/128px/*-128.png",
    Custom: ["/emoji/*.png", "/emoji/custom/*.png"]
  ]

Priority of tags assigns in emoji.txt and custom.txt:

tag in file > special group setting in config.exs > default setting in config.exs

Priority for globs:

special group setting in config.exs > default setting in config.exs

Stealing emoji

Managing your emoji can be hard work, and you just want to have the cool emoji your friends use? As usual, crime comes to the rescue!

You can use the Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy Message Rewrite Facility to automatically add to your instance emoji that messages from specific servers contain. Note that this happens on message processing, so the emoji will be added only after your instance receives some interaction containing emoji after configuring this.

To activate this you have to configure it in your configuration file. For example if you wanted to steal any emoji that is not related to cinnamon and not larger than about 10K from coolemoji.space and spiceenthusiasts.biz, you would add the following:

config :pleroma, :mrf,
  policies: [
    Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy
  ]

config :pleroma, :mrf_steal_emoji,
  hosts: [
    "coolemoji.space",
    "spiceenthusiasts.biz"
  ],
  rejected_shortcodes: [
    ".*cinnamon.*"
  ],
  size_limit: 10000

Note that this may not obey emoji licensing restrictions. It's extremely unlikely that anyone will care, but keep this in mind for when Nintendo starts their own instance.