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docs/configuration/custom_emoji.md

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+# 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 pleroma or connect to the iex session pleroma'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:
+```elixir
+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.
+```elixir
+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:
+```elixir
+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`