From 76f1ed834efd3b58b6ebc8e951b661bbc1b7bf9b Mon Sep 17 00:00:00 2001
From: Eugen Rochko <eugen@zeonfederated.com>
Date: Sat, 25 Jan 2020 05:23:05 +0100
Subject: [PATCH] Add number animations (#12948)

---
 .../mastodon/components/animated_number.js    | 47 +++++++++++++++++++
 .../components/announcements.js               |  5 +-
 .../status/components/detailed_status.js      | 11 +++--
 .../styles/mastodon/components.scss           | 12 ++++-
 4 files changed, 66 insertions(+), 9 deletions(-)
 create mode 100644 app/javascript/mastodon/components/animated_number.js

diff --git a/app/javascript/mastodon/components/animated_number.js b/app/javascript/mastodon/components/animated_number.js
new file mode 100644
index 000000000..2d359fbc6
--- /dev/null
+++ b/app/javascript/mastodon/components/animated_number.js
@@ -0,0 +1,47 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { FormattedNumber } from 'react-intl';
+import TransitionMotion from 'react-motion/lib/TransitionMotion';
+import spring from 'react-motion/lib/spring';
+import { reduceMotion } from 'mastodon/initial_state';
+
+export default class AnimatedNumber extends React.PureComponent {
+
+  static propTypes = {
+    value: PropTypes.number.isRequired,
+  };
+
+  willEnter () {
+    return { y: -1 };
+  }
+
+  willLeave () {
+    return { y: spring(1, { damping: 35, stiffness: 400 }) };
+  }
+
+  render () {
+    const { value } = this.props;
+
+    if (reduceMotion) {
+      return <FormattedNumber value={value} />;
+    }
+
+    const styles = [{
+      key: value,
+      style: { y: spring(0, { damping: 35, stiffness: 400 }) },
+    }];
+
+    return (
+      <TransitionMotion styles={styles} willEnter={this.willEnter} willLeave={this.willLeave}>
+        {items => (
+          <span className='animated-number'>
+            {items.map(({ key, style }) => (
+              <span key={key} style={{ position: style.y > 0 ? 'absolute' : 'static', transform: `translateY(${style.y * 100}%)` }}><FormattedNumber value={key} /></span>
+            ))}
+          </span>
+        )}
+      </TransitionMotion>
+    );
+  }
+
+}
diff --git a/app/javascript/mastodon/features/getting_started/components/announcements.js b/app/javascript/mastodon/features/getting_started/components/announcements.js
index ee444e3f0..18b1de127 100644
--- a/app/javascript/mastodon/features/getting_started/components/announcements.js
+++ b/app/javascript/mastodon/features/getting_started/components/announcements.js
@@ -5,13 +5,14 @@ import ImmutablePropTypes from 'react-immutable-proptypes';
 import PropTypes from 'prop-types';
 import IconButton from 'mastodon/components/icon_button';
 import Icon from 'mastodon/components/icon';
-import { defineMessages, injectIntl, FormattedMessage, FormattedDate, FormattedNumber } from 'react-intl';
+import { defineMessages, injectIntl, FormattedMessage, FormattedDate } from 'react-intl';
 import { autoPlayGif } from 'mastodon/initial_state';
 import elephantUIPlane from 'mastodon/../images/elephant_ui_plane.svg';
 import { mascot } from 'mastodon/initial_state';
 import unicodeMapping from 'mastodon/features/emoji/emoji_unicode_mapping_light';
 import classNames from 'classnames';
 import EmojiPickerDropdown from 'mastodon/features/compose/containers/emoji_picker_dropdown_container';
+import AnimatedNumber from 'mastodon/components/animated_number';
 
 const messages = defineMessages({
   close: { id: 'lightbox.close', defaultMessage: 'Close' },
@@ -225,7 +226,7 @@ class Reaction extends ImmutablePureComponent {
     return (
       <button className={classNames('reactions-bar__item', { active: reaction.get('me') })} onClick={this.handleClick} onMouseEnter={this.handleMouseEnter} onMouseLeave={this.handleMouseLeave} title={`:${shortCode}:`}>
         <span className='reactions-bar__item__emoji'><Emoji hovered={this.state.hovered} emoji={reaction.get('name')} emojiMap={this.props.emojiMap} /></span>
-        <span className='reactions-bar__item__count'><FormattedNumber value={reaction.get('count')} /></span>
+        <span className='reactions-bar__item__count'><AnimatedNumber value={reaction.get('count')} /></span>
       </button>
     );
   }
diff --git a/app/javascript/mastodon/features/status/components/detailed_status.js b/app/javascript/mastodon/features/status/components/detailed_status.js
index d5bc82735..2fec247c1 100644
--- a/app/javascript/mastodon/features/status/components/detailed_status.js
+++ b/app/javascript/mastodon/features/status/components/detailed_status.js
@@ -6,7 +6,7 @@ import DisplayName from '../../../components/display_name';
 import StatusContent from '../../../components/status_content';
 import MediaGallery from '../../../components/media_gallery';
 import { Link } from 'react-router-dom';
-import { FormattedDate, FormattedNumber } from 'react-intl';
+import { FormattedDate } from 'react-intl';
 import Card from './card';
 import ImmutablePureComponent from 'react-immutable-pure-component';
 import Video from '../../video';
@@ -14,6 +14,7 @@ import Audio from '../../audio';
 import scheduleIdleTask from '../../ui/util/schedule_idle_task';
 import classNames from 'classnames';
 import Icon from 'mastodon/components/icon';
+import AnimatedNumber from 'mastodon/components/animated_number';
 
 export default class DetailedStatus extends ImmutablePureComponent {
 
@@ -172,7 +173,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
         <Link to={`/statuses/${status.get('id')}/reblogs`} className='detailed-status__link'>
           <Icon id={reblogIcon} />
           <span className='detailed-status__reblogs'>
-            <FormattedNumber value={status.get('reblogs_count')} />
+            <AnimatedNumber value={status.get('reblogs_count')} />
           </span>
         </Link>
       );
@@ -181,7 +182,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
         <a href={`/interact/${status.get('id')}?type=reblog`} className='detailed-status__link' onClick={this.handleModalLink}>
           <Icon id={reblogIcon} />
           <span className='detailed-status__reblogs'>
-            <FormattedNumber value={status.get('reblogs_count')} />
+            <AnimatedNumber value={status.get('reblogs_count')} />
           </span>
         </a>
       );
@@ -192,7 +193,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
         <Link to={`/statuses/${status.get('id')}/favourites`} className='detailed-status__link'>
           <Icon id='star' />
           <span className='detailed-status__favorites'>
-            <FormattedNumber value={status.get('favourites_count')} />
+            <AnimatedNumber value={status.get('favourites_count')} />
           </span>
         </Link>
       );
@@ -201,7 +202,7 @@ export default class DetailedStatus extends ImmutablePureComponent {
         <a href={`/interact/${status.get('id')}?type=favourite`} className='detailed-status__link' onClick={this.handleModalLink}>
           <Icon id='star' />
           <span className='detailed-status__favorites'>
-            <FormattedNumber value={status.get('favourites_count')} />
+            <AnimatedNumber value={status.get('favourites_count')} />
           </span>
         </a>
       );
diff --git a/app/javascript/styles/mastodon/components.scss b/app/javascript/styles/mastodon/components.scss
index 6c412bc89..1e1000ff3 100644
--- a/app/javascript/styles/mastodon/components.scss
+++ b/app/javascript/styles/mastodon/components.scss
@@ -3,6 +3,14 @@
   -ms-overflow-style: -ms-autohiding-scrollbar;
 }
 
+.animated-number {
+  display: inline-flex;
+  flex-direction: column;
+  align-items: stretch;
+  overflow: hidden;
+  position: relative;
+}
+
 .link-button {
   display: block;
   font-size: 15px;
@@ -6754,10 +6762,10 @@ noscript {
     &.active {
       transition: all 100ms ease-in;
       transition-property: background-color, color;
-      background-color: mix(lighten($ui-base-color, 12%), $ui-highlight-color, 90%);
+      background-color: mix(lighten($ui-base-color, 12%), $ui-highlight-color, 80%);
 
       .reactions-bar__item__count {
-        color: $highlight-text-color;
+        color: lighten($highlight-text-color, 8%);
       }
     }
   }