Add a simple TagComposer for the keywords entry

res/css/_components.scss

@@ -148,6 +148,7 @@
 @import "./views/elements/_StyledCheckbox.scss";
 @import "./views/elements/_StyledRadioButton.scss";
 @import "./views/elements/_SyntaxHighlight.scss";
+@import "./views/elements/_TagComposer.scss";
 @import "./views/elements/_TextWithTooltip.scss";
 @import "./views/elements/_ToggleSwitch.scss";
 @import "./views/elements/_Tooltip.scss";
@@ -260,9 +261,9 @@
 @import "./views/toasts/_NonUrgentEchoFailureToast.scss";
 @import "./views/verification/_VerificationShowSas.scss";
 @import "./views/voip/_CallContainer.scss";
+@import "./views/voip/_CallPreview.scss";
 @import "./views/voip/_CallView.scss";
 @import "./views/voip/_CallViewForRoom.scss";
-@import "./views/voip/_CallPreview.scss";
 @import "./views/voip/_DialPad.scss";
 @import "./views/voip/_DialPadContextMenu.scss";
 @import "./views/voip/_DialPadModal.scss";

res/css/views/elements/_TagComposer.scss

@@ -0,0 +1,77 @@
+/*
+Copyright 2021 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_TagComposer {
+    .mx_TagComposer_input {
+        display: flex;
+
+        .mx_Field {
+            flex: 1;
+            margin: 0; // override from field styles
+        }
+
+        .mx_AccessibleButton {
+            min-width: 70px;
+            padding: 0; // override from button styles
+            margin-left: 16px; // distance from <Field>
+        }
+
+        .mx_Field, .mx_Field input, .mx_AccessibleButton {
+            // So they look related to each other by feeling the same
+            border-radius: 8px;
+        }
+    }
+
+    .mx_TagComposer_tags {
+        display: flex;
+        flex-wrap: wrap;
+        margin-top: 12px; // this plus 12px from the tags makes 24px from the input
+
+        .mx_TagComposer_tag {
+            padding: 6px 8px 8px 12px;
+            position: relative;
+            margin-right: 12px;
+            margin-top: 12px;
+
+            // Cheaty way to get an opacified variable colour background
+            &::before {
+                content: '';
+                border-radius: 20px;
+                background-color: $tertiary-fg-color;
+                opacity: 0.15;
+                position: absolute;
+                top: 0;
+                left: 0;
+                width: 100%;
+                height: 100%;
+
+                // Pass through the pointer otherwise we have effectively put a whole div
+                // on top of the component, which makes it hard to interact with buttons.
+                pointer-events: none;
+            }
+        }
+
+        .mx_AccessibleButton {
+            background-image: url('$(res)/img/subtract.svg');
+            width: 16px;
+            height: 16px;
+            margin-left: 8px;
+            display: inline-block;
+            vertical-align: middle;
+            cursor: pointer;
+        }
+    }
+}

res/img/subtract.svg

@@ -0,0 +1,3 @@
+<svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path fill-rule="evenodd" clip-rule="evenodd" d="M8 16C12.4183 16 16 12.4183 16 8C16 3.58167 12.4183 0 8 0C3.58173 0 0 3.58167 0 8C0 12.4183 3.58173 16 8 16ZM3.96967 5.0304L6.93933 8L3.96967 10.9697L5.03033 12.0304L8 9.06067L10.9697 12.0304L12.0303 10.9697L9.06067 8L12.0303 5.0304L10.9697 3.96973L8 6.93945L5.03033 3.96973L3.96967 5.0304Z" fill="#8D97A5"/>
+</svg>

src/components/views/elements/TagComposer.tsx

@@ -0,0 +1,91 @@
+/*
+Copyright 2021 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, { ChangeEvent, FormEvent } from "react";
+import { replaceableComponent } from "../../../utils/replaceableComponent";
+import Field from "./Field";
+import { _t } from "../../../languageHandler";
+import AccessibleButton from "./AccessibleButton";
+
+interface IProps {
+    tags: string[];
+    onAdd: (tag: string) => void;
+    onRemove: (tag: string) => void;
+    disabled?: boolean;
+    label?: string;
+    placeholder?: string;
+}
+
+interface IState {
+    newTag: string;
+}
+
+/**
+ * A simple, controlled, composer for entering string tags. Contains a simple
+ * input, add button, and per-tag remove button.
+ */
+@replaceableComponent("views.elements.TagComposer")
+export default class TagComposer extends React.PureComponent<IProps, IState> {
+    public constructor(props: IProps) {
+        super(props);
+
+        this.state = {
+            newTag: "",
+        };
+    }
+
+    private onInputChange = (ev: ChangeEvent<HTMLInputElement>) => {
+        this.setState({ newTag: ev.target.value });
+    };
+
+    private onAdd = (ev: FormEvent) => {
+        ev.preventDefault();
+        if (!this.state.newTag) return;
+
+        this.props.onAdd(this.state.newTag);
+        this.setState({ newTag: "" });
+    };
+
+    private onRemove = (tag: string) => {
+        // We probably don't need to proxy this, but for
+        // sanity of `this` we'll do so anyways.
+        this.props.onRemove(tag);
+    };
+
+    public render() {
+        return <div className='mx_TagComposer'>
+            <form className='mx_TagComposer_input' onSubmit={this.onAdd}>
+                <Field
+                    value={this.state.newTag}
+                    onChange={this.onInputChange}
+                    label={this.props.label || _t("Keyword")}
+                    placeholder={this.props.placeholder || _t("New keyword")}
+                    disabled={this.props.disabled}
+                    autoComplete="off"
+                />
+                <AccessibleButton onClick={this.onAdd} kind='primary' disabled={this.props.disabled}>
+                    { _t("Add") }
+                </AccessibleButton>
+            </form>
+            <div className='mx_TagComposer_tags'>
+                { this.props.tags.map((t, i) => (<div className='mx_TagComposer_tag' key={i}>
+                    <span>{ t }</span>
+                    <AccessibleButton onClick={this.onRemove.bind(this, t)} disabled={this.props.disabled} />
+                </div>)) }
+            </div>
+        </div>;
+    }
+}