Play animated custom emoji on hover (#11348)

* Play animated custom emoji on hover in status

* Play animated custom emoji on hover in display names

* Play animated custom emoji on hover in bios/bio fields

* Add support for animation on hover on public pages emojis too

* Fix tests

* Code style cleanup

1 files changed, 42 insertions, 1 deletions

diff --git a/app/javascript/mastodon/features/account/components/header.js b/app/javascript/mastodon/features/account/components/header.js
index e5b60e33e..cab67c607 100644
--- a/app/javascript/mastodon/features/account/components/header.js
+++ b/app/javascript/mastodon/features/account/components/header.js
@@ -79,6 +79,47 @@ class Header extends ImmutablePureComponent {
     return !location.pathname.match(/\/(followers|following)\/?$/);
   }
 
+  _updateEmojis () {
+    const node = this.node;
+
+    if (!node || autoPlayGif) {
+      return;
+    }
+
+    const emojis = node.querySelectorAll('.custom-emoji');
+
+    for (var i = 0; i < emojis.length; i++) {
+      let emoji = emojis[i];
+      if (emoji.classList.contains('status-emoji')) {
+        continue;
+      }
+      emoji.classList.add('status-emoji');
+
+      emoji.addEventListener('mouseenter', this.handleEmojiMouseEnter, false);
+      emoji.addEventListener('mouseleave', this.handleEmojiMouseLeave, false);
+    }
+  }
+
+  componentDidMount () {
+    this._updateEmojis();
+  }
+
+  componentDidUpdate () {
+    this._updateEmojis();
+  }
+
+  handleEmojiMouseEnter = ({ target }) => {
+    target.src = target.getAttribute('data-original');
+  }
+
+  handleEmojiMouseLeave = ({ target }) => {
+    target.src = target.getAttribute('data-static');
+  }
+
+  setRef = (c) => {
+    this.node = c;
+  }
+
   render () {
     const { account, intl, domain, identity_proofs } = this.props;
 
@@ -200,7 +241,7 @@ class Header extends ImmutablePureComponent {
     const acct            = account.get('acct').indexOf('@') === -1 && domain ? `${account.get('acct')}@${domain}` : account.get('acct');
 
     return (
-      <div className={classNames('account__header', { inactive: !!account.get('moved') })}>
+      <div className={classNames('account__header', { inactive: !!account.get('moved') })} ref={this.setRef}>
         <div className='account__header__image'>
           <div className='account__header__info'>
             {info}