Add Keyboard Shortcuts Legend (#5823)

* Add Keyboard Shortcuts Legend

Adds a "Keyboard Shortcuts" legend (displayed in the rightmost column)
which is toggled via a new "?" hotkey. When subsequently pressed from
the Keyboard Shortcuts legend, "?" will navigate back to the previous
location.

* Add hidden table headings.

Makes the headings available for accessibility but hides them visually.

1 files changed, 68 insertions, 0 deletions

diff --git a/app/javascript/mastodon/features/keyboard_shortcuts/index.js b/app/javascript/mastodon/features/keyboard_shortcuts/index.js
new file mode 100644
index 000000000..00771b79c
--- /dev/null
+++ b/app/javascript/mastodon/features/keyboard_shortcuts/index.js
@@ -0,0 +1,68 @@
+import React from 'react';
+import Column from '../ui/components/column';
+import { defineMessages, injectIntl } from 'react-intl';
+import PropTypes from 'prop-types';
+import ImmutablePureComponent from 'react-immutable-pure-component';
+
+const messages = defineMessages({
+  heading: { id: 'keyboard_shortcuts.heading', defaultMessage: 'Keyboard Shortcuts' },
+  hotkey: { id: 'keyboard_shortcuts.hotkey', defaultMessage: 'Hotkey' },
+  description: { id: 'keyboard_shortcuts.description', defaultMessage: 'Description' },
+  reply: { id: 'keyboard_shortcuts.reply', defaultMessage: 'to reply' },
+  mention: { id: 'keyboard_shortcuts.mention', defaultMessage: 'to mention author' },
+  favourite: { id: 'keyboard_shortcuts.favourite', defaultMessage: 'to favourite' },
+  boost: { id: 'keyboard_shortcuts.boost', defaultMessage: 'to boost' },
+  enter: { id: 'keyboard_shortcuts.enter', defaultMessage: 'to open status' },
+  profile: { id: 'keyboard_shortcuts.profile', defaultMessage: 'to open author\'s profile' },
+  up: { id: 'keyboard_shortcuts.up', defaultMessage: 'to move up in the list' },
+  down: { id: 'keyboard_shortcuts.down', defaultMessage: 'to move down in the list' },
+  column: { id: 'keyboard_shortcuts.column', defaultMessage: 'to focus a status in one of the columns' },
+  compose: { id: 'keyboard_shortcuts.compose', defaultMessage: 'to focus the compose textarea' },
+  toot: { id: 'keyboard_shortcuts.toot', defaultMessage: 'to start a brand new toot' },
+  back: { id: 'keyboard_shortcuts.back', defaultMessage: 'to navigate back' },
+  search: { id: 'keyboard_shortcuts.search', defaultMessage: 'to focus search' },
+  unfocus: { id: 'keyboard_shortcuts.unfocus', defaultMessage: 'to un-focus compose textarea/search' },
+  legend: { id: 'keyboard_shortcuts.legend', defaultMessage: 'to display this legend' },
+});
+
+@injectIntl
+export default class KeyboardShortcuts extends ImmutablePureComponent {
+
+  static propTypes = {
+    intl: PropTypes.object.isRequired,
+    multiColumn: PropTypes.bool,
+  };
+
+  render () {
+    const { intl } = this.props;
+
+    return (
+      <Column icon='question' heading={intl.formatMessage(messages.heading)} hideHeadingOnMobile>
+        <div className='keyboard-shortcuts scrollable optionally-scrollable'>
+          <table>
+            <thead>
+              <tr><th>{intl.formatMessage(messages.hotkey)}</th><th>{intl.formatMessage(messages.description)}</th></tr>
+            </thead>
+            <tbody>
+              <tr><td><code>r</code></td><td>{intl.formatMessage(messages.reply)}</td></tr>
+              <tr><td><code>m</code></td><td>{intl.formatMessage(messages.mention)}</td></tr>
+              <tr><td><code>f</code></td><td>{intl.formatMessage(messages.favourite)}</td></tr>
+              <tr><td><code>b</code></td><td>{intl.formatMessage(messages.boost)}</td></tr>
+              <tr><td><code>enter</code></td><td>{intl.formatMessage(messages.enter)}</td></tr>
+              <tr><td><code>up</code></td><td>{intl.formatMessage(messages.up)}</td></tr>
+              <tr><td><code>down</code></td><td>{intl.formatMessage(messages.down)}</td></tr>
+              <tr><td><code>1</code>-<code>9</code></td><td>{intl.formatMessage(messages.column)}</td></tr>
+              <tr><td><code>n</code></td><td>{intl.formatMessage(messages.compose)}</td></tr>
+              <tr><td><code>alt</code>+<code>n</code></td><td>{intl.formatMessage(messages.toot)}</td></tr>
+              <tr><td><code>backspace</code></td><td>{intl.formatMessage(messages.back)}</td></tr>
+              <tr><td><code>s</code></td><td>{intl.formatMessage(messages.search)}</td></tr>
+              <tr><td><code>esc</code></td><td>{intl.formatMessage(messages.unfocus)}</td></tr>
+              <tr><td><code>?</code></td><td>{intl.formatMessage(messages.legend)}</td></tr>
+            </tbody>
+          </table>
+        </div>
+      </Column>
+    );
+  }
+
+}