Add a basic tooltip showing who reacted

This adds a first attempt at tooltip showing who reacted to a message. It
doesn't limit senders or position the tooltip nicely, but the info is there at
least.

Part of https://github.com/vector-im/riot-web/issues/9722

res/css/_components.scss

@@ -119,6 +119,7 @@
 @import "./views/messages/_ReactionDimension.scss";
 @import "./views/messages/_ReactionsRow.scss";
 @import "./views/messages/_ReactionsRowButton.scss";
+@import "./views/messages/_ReactionsRowButtonTooltip.scss";
 @import "./views/messages/_RoomAvatarEvent.scss";
 @import "./views/messages/_SenderProfile.scss";
 @import "./views/messages/_TextualEvent.scss";

res/css/views/messages/_ReactionsRowButtonTooltip.scss

@@ -0,0 +1,34 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+.mx_ReactionsRowButtonTooltip {
+    box-shadow: none;
+    background-color: $reaction-row-button-tooltip-bg-color;
+    color: $reaction-row-button-tooltip-fg-color;
+    text-align: center;
+    font-size: 8px;
+    padding: 6px;
+    border: none;
+    border-radius: 3px;
+
+    .mx_Tooltip_chevron::after {
+        border-right-color: $reaction-row-button-tooltip-bg-color;
+    }
+
+    .mx_ReactionsRowButtonTooltip_reactedWith {
+        opacity: 0.7;
+    }
+}

res/themes/dark/css/_dark.scss

@@ -156,6 +156,8 @@ $reaction-row-button-border-color: #616b7f;
 $reaction-row-button-hover-border-color: $header-panel-text-primary-color;
 $reaction-row-button-selected-bg-color: #1f6954;
 $reaction-row-button-selected-border-color: $accent-color;
+$reaction-row-button-tooltip-bg-color: $tagpanel-bg-color;
+$reaction-row-button-tooltip-fg-color: #ffffff;
 
 // ***** Mixins! *****
 

res/themes/light/css/_light.scss

@@ -264,6 +264,8 @@ $reaction-row-button-border-color: #e9edf1;
 $reaction-row-button-hover-border-color: $focus-bg-color;
 $reaction-row-button-selected-bg-color: #e9fff9;
 $reaction-row-button-selected-border-color: $accent-color;
+$reaction-row-button-tooltip-bg-color: $tagpanel-bg-color;
+$reaction-row-button-tooltip-fg-color: #ffffff;
 
 // ***** Mixins! *****
 

src/HtmlUtils.js

@@ -107,6 +107,17 @@ function unicodeToImage(str, addAlt) {
     return str;
 }
 
+/**
+ * Returns the shortcode for an emoji character.
+ *
+ * @param {String} char The emoji character
+ * @return {String} The shortcode (such as :thumbup:)
+ */
+export function unicodeToShort(char) {
+    const unicode = emojione.jsEscapeMap[char];
+    return emojione.mapUnicodeToShort()[unicode];
+}
+
 /**
  * Given one or more unicode characters (represented by unicode
  * character number), return an image node with the corresponding

src/components/views/messages/ReactionsRow.js

@@ -116,8 +116,8 @@ export default class ReactionsRow extends React.PureComponent {
             return <ReactionsRowButton
                 key={content}
                 content={content}
-                count={count}
                 mxEvent={mxEvent}
+                reactionEvents={events}
                 myReactionEvent={myReactionEvent}
             />;
         });

src/components/views/messages/ReactionsRowButton.js

@@ -19,17 +19,28 @@ import PropTypes from 'prop-types';
 import classNames from 'classnames';
 
 import MatrixClientPeg from '../../../MatrixClientPeg';
+import sdk from '../../../index';
 
 export default class ReactionsRowButton extends React.PureComponent {
     static propTypes = {
         // The event we're displaying reactions for
         mxEvent: PropTypes.object.isRequired,
+        // The reaction content / key / emoji
         content: PropTypes.string.isRequired,
-        count: PropTypes.number.isRequired,
+        // A Set of Martix reaction events for this key
+        reactionEvents: PropTypes.object.isRequired,
         // A possible Matrix event if the current user has voted for this type
         myReactionEvent: PropTypes.object,
     }
 
+    constructor(props) {
+        super(props);
+
+        this.state = {
+            tooltipVisible: false,
+        };
+    }
+
     onClick = (ev) => {
         const { mxEvent, myReactionEvent, content } = this.props;
         if (myReactionEvent) {
@@ -48,18 +59,53 @@ export default class ReactionsRowButton extends React.PureComponent {
         }
     };
 
+    onMouseOver = () => {
+        this.setState({
+            // To avoid littering the DOM with a tooltip for every reaction,
+            // only render it on first use.
+            tooltipRendered: true,
+            tooltipVisible: true,
+        });
+    }
+
+    onMouseOut = () => {
+        this.setState({
+            tooltipVisible: false,
+        });
+    }
+
     render() {
-        const { content, count, myReactionEvent } = this.props;
+        const ReactionsRowButtonTooltip =
+            sdk.getComponent('messages.ReactionsRowButtonTooltip');
+        const { content, reactionEvents, myReactionEvent } = this.props;
+
+        const count = reactionEvents.size;
+        if (!count) {
+            return null;
+        }
 
         const classes = classNames({
             mx_ReactionsRowButton: true,
             mx_ReactionsRowButton_selected: !!myReactionEvent,
         });
 
+        let tooltip;
+        if (this.state.tooltipRendered) {
+            tooltip = <ReactionsRowButtonTooltip
+                mxEvent={this.props.mxEvent}
+                content={content}
+                reactionEvents={reactionEvents}
+                visible={this.state.tooltipVisible}
+            />;
+        }
+
         return <span className={classes}
             onClick={this.onClick}
+            onMouseOver={this.onMouseOver}
+            onMouseOut={this.onMouseOut}
         >
             {content} {count}
+            {tooltip}
         </span>;
     }
 }

src/components/views/messages/ReactionsRowButtonTooltip.js

@@ -0,0 +1,80 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import PropTypes from 'prop-types';
+
+import MatrixClientPeg from '../../../MatrixClientPeg';
+import sdk from '../../../index';
+import { unicodeToShort } from '../../../HtmlUtils';
+import { _t } from '../../../languageHandler';
+
+export default class ReactionsRowButtonTooltip extends React.PureComponent {
+    static propTypes = {
+        // The event we're displaying reactions for
+        mxEvent: PropTypes.object.isRequired,
+        // The reaction content / key / emoji
+        content: PropTypes.string.isRequired,
+        // A Set of Martix reaction events for this key
+        reactionEvents: PropTypes.object.isRequired,
+        visible: PropTypes.bool.isRequired,
+    }
+
+    render() {
+        const Tooltip = sdk.getComponent('elements.Tooltip');
+        const { content, reactionEvents, mxEvent, visible } = this.props;
+
+        const room = MatrixClientPeg.get().getRoom(mxEvent.getRoomId());
+        let tooltipLabel;
+        if (room) {
+            const senders = [];
+            for (const reactionEvent of reactionEvents) {
+                const { name } = room.getMember(reactionEvent.getSender());
+                senders.push(name);
+            }
+            const shortName = unicodeToShort(content) || content;
+            tooltipLabel = <div>{_t(
+                "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>",
+                {
+                    shortName,
+                },
+                {
+                    reactors: () => {
+                        return <div className="mx_ReactionsRowButtonTooltip_senders">
+                            {senders.join(", ")}
+                        </div>;
+                    },
+                    reactedWith: (sub) => {
+                        return <div className="mx_ReactionsRowButtonTooltip_reactedWith">
+                            {sub}
+                        </div>;
+                    },
+                },
+            )}</div>;
+        }
+
+        let tooltip;
+        if (tooltipLabel) {
+            tooltip = <Tooltip
+                tooltipClassName="mx_ReactionsRowButtonTooltip"
+                visible={visible}
+                label={tooltipLabel}
+            />;
+        }
+
+        return tooltip;
+    }
+}

src/i18n/strings/en_EN.json

@@ -907,6 +907,7 @@
     "Invalid file%(extra)s": "Invalid file%(extra)s",
     "Error decrypting image": "Error decrypting image",
     "Error decrypting video": "Error decrypting video",
+    "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>": "<reactors/><reactedWith>reacted with %(shortName)s</reactedWith>",
     "%(senderDisplayName)s changed the avatar for %(roomName)s": "%(senderDisplayName)s changed the avatar for %(roomName)s",
     "%(senderDisplayName)s removed the room avatar.": "%(senderDisplayName)s removed the room avatar.",
     "%(senderDisplayName)s changed the room avatar to <img/>": "%(senderDisplayName)s changed the room avatar to <img/>",