Merge pull request #6262 from matrix-org/gsouquet/fix-backdrop-filter

Move backdrop filter to a canvas based solution

package.json

@@ -64,6 +64,7 @@
     "cheerio": "^1.0.0-rc.9",
     "classnames": "^2.2.6",
     "commonmark": "^0.29.3",
+    "context-filter-polyfill": "^0.2.4",
     "counterpart": "^0.18.6",
     "diff-dom": "^4.2.2",
     "diff-match-patch": "^1.0.5",
@@ -195,6 +196,7 @@
       "decoderWorker\\.min\\.js": "<rootDir>/__mocks__/empty.js",
       "decoderWorker\\.min\\.wasm": "<rootDir>/__mocks__/empty.js",
       "waveWorker\\.min\\.js": "<rootDir>/__mocks__/empty.js",
+      "context-filter-polyfill": "<rootDir>/__mocks__/empty.js",
       "workers/(.+)\\.worker\\.ts": "<rootDir>/__mocks__/workerMock.js",
       "RecorderWorklet": "<rootDir>/__mocks__/empty.js"
     },

res/css/_common.scss

@@ -168,7 +168,7 @@ input[type=text]:focus, input[type=password]:focus, textarea:focus {
 // it has the appearance of a text box so the controls
 // appear to be part of the input
 
-.mx_Dialog, .mx_MatrixChat {
+.mx_Dialog, .mx_MatrixChat_wrapper {
     .mx_textinput > input[type=text],
     .mx_textinput > input[type=search] {
         border: none;

res/css/_components.scss

@@ -17,6 +17,7 @@
 @import "./structures/_LeftPanelWidget.scss";
 @import "./structures/_MainSplit.scss";
 @import "./structures/_MatrixChat.scss";
+@import "./structures/_BackdropPanel.scss";
 @import "./structures/_MyGroups.scss";
 @import "./structures/_NonUrgentToastContainer.scss";
 @import "./structures/_NotificationPanel.scss";

res/css/structures/_BackdropPanel.scss

@@ -0,0 +1,51 @@
+/*
+Copyright 2021 New Vector Ltd
+
+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_BackdropPanel {
+    position: absolute;
+    left: 0;
+    top: 0;
+    height: 100vh;
+    width: 100%;
+    overflow: hidden;
+
+    &::before {
+        content: " ";
+        position: absolute;
+        left: 0;
+        top: 0;
+        height: 100vh;
+        width: 100%;
+        background-color: var(--lp-background-overlay);
+    }
+}
+
+.mx_BackdropPanel--canvas {
+    position: absolute;
+    top: 0;
+    left: 0;
+    min-height: 100%;
+    z-index: 0;
+    pointer-events: none;
+    overflow: hidden;
+
+    &:nth-of-type(2n-1) {
+        opacity: 0.2;
+    }
+    &:nth-of-type(2n) {
+        opacity: 0.1;
+    }
+}

res/css/structures/_GroupFilterPanel.scss

@@ -14,10 +14,17 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+.mx_MatrixChat--with-avatar {
+    .mx_GroupFilterPanel {
+        background-color: transparent;
+    }
+}
+
 .mx_GroupFilterPanel {
-    flex: 1;
     background-color: $groupFilterPanel-bg-color;
+    flex: 1;
     cursor: pointer;
+    position: relative;
 
     display: flex;
     flex-direction: column;

res/css/structures/_LeftPanel.scss

@@ -17,15 +17,22 @@ limitations under the License.
 $groupFilterPanelWidth: 56px; // only applies in this file, used for calculations
 $roomListCollapsedWidth: 68px;
 
+.mx_MatrixChat--with-avatar {
+    .mx_LeftPanel,
+    .mx_LeftPanel .mx_LeftPanel_roomListContainer {
+        background-color: transparent;
+    }
+}
+
 .mx_LeftPanel {
     background-color: $roomlist-bg-color;
     // TODO decrease this once Spaces launches as it'll no longer need to include the 56px Community Panel
     min-width: 206px;
-    max-width: 50%;
 
     // Create a row-based flexbox for the GroupFilterPanel and the room list
     display: flex;
     contain: content;
+    position: relative;
 
     .mx_LeftPanel_GroupFilterPanelContainer {
         flex-grow: 0;

res/css/structures/_MatrixChat.scss

@@ -29,8 +29,6 @@ limitations under the License.
 .mx_MatrixChat_wrapper {
     display: flex;
 
-    flex-direction: column;
-
     width: 100%;
     height: 100%;
 }
@@ -42,15 +40,16 @@ limitations under the License.
 }
 
 .mx_MatrixChat {
+    position: relative;
     width: 100%;
     height: 100%;
 
     display: flex;
 
-    order: 2;
-
     flex: 1;
+    flex-grow: 0;
     min-height: 0;
+    max-width: 50%;
 }
 
 .mx_MatrixChat_syncError {

res/css/structures/_RoomView.scss

@@ -18,6 +18,8 @@ limitations under the License.
     word-wrap: break-word;
     display: flex;
     flex-direction: column;
+    flex: 1;
+    position: relative;
 }
 
 

res/css/structures/_SpacePanel.scss

@@ -22,11 +22,18 @@ $activeBorderTransparentGap: 1px;
 $activeBackgroundColor: $roomtile-selected-bg-color;
 $activeBorderColor: $secondary-fg-color;
 
+.mx_MatrixChat--with-avatar {
+    .mx_SpacePanel {
+        background-color: transparent;
+    }
+}
+
 .mx_SpacePanel {
-    flex: 0 0 auto;
     background-color: $groupFilterPanel-bg-color;
+    flex: 0 0 auto;
     padding: 0;
     margin: 0;
+    position: relative;
 
     // Create another flexbox so the Panel fills the container
     display: flex;

res/themes/dark/css/_dark.scss

@@ -238,9 +238,12 @@ $voice-playback-button-fg-color: $message-body-panel-icon-fg-color;
 // Appearance tab colors
 $appearance-tab-border-color: $room-highlight-color;
 
-// blur amounts for left left panel (only for element theme, used in _mods.scss)
+// blur amounts for left left panel (only for element theme)
-$roomlist-background-blur-amount: 60px;
+:root {
-$groupFilterPanel-background-blur-amount: 30px;
+    --llp-background-blur: 160px;
+    --lp-background-blur: 90px;
+    --lp-background-overlay: rgba(255, 255, 255, 0.055);
+}
 
 $composer-shadow-color: rgba(0, 0, 0, 0.28);
 

res/themes/dark/css/dark.scss

@@ -2,10 +2,6 @@
 @import "../../light/css/_paths.scss";
 @import "../../light/css/_fonts.scss";
 @import "../../light/css/_light.scss";
-// important this goes before _mods,
-// as $groupFilterPanel-background-blur-amount and
-// $roomlist-background-blur-amount
-// are overridden in _dark.scss
 @import "_dark.scss";
 @import "../../light/css/_mods.scss";
 @import "../../../../res/css/_components.scss";

res/themes/light/css/_light.scss

@@ -361,10 +361,12 @@ $voice-playback-button-fg-color: $message-body-panel-icon-fg-color;
 // FontSlider colors
 $appearance-tab-border-color: $input-darker-bg-color;
 
-// blur amounts for left left panel (only for element theme, used in _mods.scss)
+// blur amounts for left left panel (only for element theme)
-$roomlist-background-blur-amount: 40px;
+:root {
-$groupFilterPanel-background-blur-amount: 20px;
+    --llp-background-blur: 120px;
-
+    --lp-background-blur: 60px;
+    --lp-background-overlay: rgba(0, 0, 0, 0.055);
+}
 $composer-shadow-color: rgba(0, 0, 0, 0.04);
 
 // Bubble tiles

res/themes/light/css/_mods.scss

@@ -4,27 +4,6 @@
 // set the user avatar (if any) as a background so
 // it can be blurred by the tag panel and room list
 
-@supports (backdrop-filter: none) {
-    .mx_LeftPanel {
-        background-image: var(--avatar-url, unset);
-        background-repeat: no-repeat;
-        background-size: cover;
-        background-position: left top;
-    }
-
-    .mx_GroupFilterPanel {
-        backdrop-filter: blur($groupFilterPanel-background-blur-amount);
-    }
-
-    .mx_SpacePanel {
-        backdrop-filter: blur($groupFilterPanel-background-blur-amount);
-    }
-
-    .mx_LeftPanel .mx_LeftPanel_roomListContainer {
-        backdrop-filter: blur($roomlist-background-blur-amount);
-    }
-}
-
 .mx_RoomSublist_showNButton {
     background-color: transparent !important;
 }

src/components/structures/BackdropPanel.tsx

@@ -0,0 +1,165 @@
+/*
+Copyright 2021 New Vector Ltd
+
+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, { createRef } from "react";
+import "context-filter-polyfill";
+
+import UIStore from "../../stores/UIStore";
+
+interface IProps {
+    backgroundImage?: CanvasImageSource;
+}
+
+interface IState {
+    // Left Panel image
+    lpImage?: string;
+    // Left-left panel image
+    llpImage?: string;
+}
+
+export default class BackdropPanel extends React.PureComponent<IProps, IState> {
+    private leftLeftPanelRef = createRef<HTMLCanvasElement>();
+    private leftPanelRef = createRef<HTMLCanvasElement>();
+
+    private sizes = {
+        leftLeftPanelWidth: 0,
+        leftPanelWidth: 0,
+        height: 0,
+    };
+    private style = getComputedStyle(document.documentElement);
+
+    public state: IState = {};
+
+    public componentDidMount() {
+        UIStore.instance.on("SpacePanel", this.onResize);
+        UIStore.instance.on("GroupFilterPanelContainer", this.onResize);
+        this.onResize();
+    }
+
+    public componentWillUnmount() {
+        UIStore.instance.off("SpacePanel", this.onResize);
+        UIStore.instance.on("GroupFilterPanelContainer", this.onResize);
+    }
+
+    public componentDidUpdate(prevProps: IProps) {
+        if (prevProps.backgroundImage !== this.props.backgroundImage) {
+            this.setState({});
+            this.onResize();
+        }
+    }
+
+    private onResize = () => {
+        if (this.props.backgroundImage) {
+            const groupFilterPanelDimensions = UIStore.instance.getElementDimensions("GroupFilterPanelContainer");
+            const spacePanelDimensions = UIStore.instance.getElementDimensions("SpacePanel");
+            const roomListDimensions = UIStore.instance.getElementDimensions("LeftPanel");
+            this.sizes = {
+                leftLeftPanelWidth: spacePanelDimensions?.width ?? groupFilterPanelDimensions?.width ?? 0,
+                leftPanelWidth: roomListDimensions?.width ?? 0,
+                height: UIStore.instance.windowHeight,
+            };
+            this.refreshBackdropImage();
+        }
+    };
+
+    private refreshBackdropImage = (): void => {
+        const leftLeftPanelContext = this.leftLeftPanelRef.current.getContext("2d");
+        const leftPanelContext = this.leftPanelRef.current.getContext("2d");
+        const { leftLeftPanelWidth, leftPanelWidth, height } = this.sizes;
+        const width = leftLeftPanelWidth + leftPanelWidth;
+        const { backgroundImage } = this.props;
+
+        const imageWidth = (backgroundImage as ImageBitmap).width;
+        const imageHeight = (backgroundImage as ImageBitmap).height;
+
+        const contentRatio = imageWidth / imageHeight;
+        const containerRatio = width / height;
+        let resultHeight;
+        let resultWidth;
+        if (contentRatio > containerRatio) {
+            resultHeight = height;
+            resultWidth = height * contentRatio;
+        } else {
+            resultWidth = width;
+            resultHeight = width / contentRatio;
+        }
+
+        // This value has been chosen to be as close with rendering as the css-only
+        // backdrop-filter: blur effect was, mostly takes effect for vertical pictures.
+        const x = width * 0.1;
+        const y = (height - resultHeight) / 2;
+
+        this.leftLeftPanelRef.current.width = leftLeftPanelWidth;
+        this.leftLeftPanelRef.current.height = height;
+        this.leftPanelRef.current.width = (window.screen.width * 0.5);
+        this.leftPanelRef.current.height = height;
+
+        const spacesBlur = this.style.getPropertyValue('--llp-background-blur');
+        const roomListBlur = this.style.getPropertyValue('--lp-background-blur');
+
+        leftLeftPanelContext.filter = `blur(${spacesBlur})`;
+        leftPanelContext.filter = `blur(${roomListBlur})`;
+        leftLeftPanelContext.drawImage(
+            backgroundImage,
+            0, 0,
+            imageWidth, imageHeight,
+            x,
+            y,
+            resultWidth,
+            resultHeight,
+        );
+        leftPanelContext.drawImage(
+            backgroundImage,
+            0, 0,
+            imageWidth, imageHeight,
+            x - leftLeftPanelWidth,
+            y,
+            resultWidth,
+            resultHeight,
+        );
+        this.setState({
+            lpImage: this.leftPanelRef.current.toDataURL('image/jpeg', 1),
+            llpImage: this.leftLeftPanelRef.current.toDataURL('image/jpeg', 1),
+
+        });
+    };
+
+    public render() {
+        if (!this.props.backgroundImage) return null;
+        return <div className="mx_BackdropPanel">
+            <img
+                className="mx_BackdropPanel--canvas"
+                src={this.state.llpImage} />
+            <img
+                className="mx_BackdropPanel--canvas"
+                src={this.state.lpImage} />
+            <canvas
+                ref={this.leftLeftPanelRef}
+                className="mx_BackdropPanel--canvas"
+                style={{
+                    display: this.state.lpImage ? 'none' : 'block',
+                }}
+            />
+            <canvas
+                style={{
+                    display: this.state.lpImage ? 'none' : 'block',
+                }}
+                ref={this.leftPanelRef}
+                className="mx_BackdropPanel--canvas"
+            />
+        </div>;
+    }
+}

src/components/structures/GroupFilterPanel.tsx

@@ -15,6 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+import type { EventSubscription } from "fbemitter";
 import React from 'react';
 import GroupFilterOrderStore from '../../stores/GroupFilterOrderStore';
 
@@ -30,22 +31,43 @@ import AutoHideScrollbar from "./AutoHideScrollbar";
 import SettingsStore from "../../settings/SettingsStore";
 import UserTagTile from "../views/elements/UserTagTile";
 import { replaceableComponent } from "../../utils/replaceableComponent";
+import UIStore from "../../stores/UIStore";
+
+interface IGroupFilterPanelProps {
+
+}
+
+// FIXME: Properly type this after migrating GroupFilterOrderStore.js to Typescript
+type OrderedTagsTemporaryType = Array<{}>;
+// FIXME: Properly type this after migrating GroupFilterOrderStore.js to Typescript
+type SelectedTagsTemporaryType = Array<{}>;
+
+interface IGroupFilterPanelState {
+    // FIXME: Properly type this after migrating GroupFilterOrderStore.js to Typescript
+    orderedTags: OrderedTagsTemporaryType;
+    // FIXME: Properly type this after migrating GroupFilterOrderStore.js to Typescript
+    selectedTags: SelectedTagsTemporaryType;
+}
 
 @replaceableComponent("structures.GroupFilterPanel")
-class GroupFilterPanel extends React.Component {
+class GroupFilterPanel extends React.Component<IGroupFilterPanelProps, IGroupFilterPanelState> {
-    static contextType = MatrixClientContext;
+    public static contextType = MatrixClientContext;
 
-    state = {
+    public state = {
         orderedTags: [],
         selectedTags: [],
     };
 
-    componentDidMount() {
+    private ref = React.createRef<HTMLDivElement>();
-        this.unmounted = false;
+    private unmounted = false;
-        this.context.on("Group.myMembership", this._onGroupMyMembership);
+    private groupFilterOrderStoreToken?: EventSubscription;
-        this.context.on("sync", this._onClientSync);
 
-        this._groupFilterOrderStoreToken = GroupFilterOrderStore.addListener(() => {
+    public componentDidMount() {
+        this.unmounted = false;
+        this.context.on("Group.myMembership", this.onGroupMyMembership);
+        this.context.on("sync", this.onClientSync);
+
+        this.groupFilterOrderStoreToken = GroupFilterOrderStore.addListener(() => {
             if (this.unmounted) {
                 return;
             }
@@ -56,23 +78,25 @@ class GroupFilterPanel extends React.Component {
         });
         // This could be done by anything with a matrix client
         dis.dispatch(GroupActions.fetchJoinedGroups(this.context));
+        UIStore.instance.trackElementDimensions("GroupPanel", this.ref.current);
     }
 
-    componentWillUnmount() {
+    public componentWillUnmount() {
         this.unmounted = true;
-        this.context.removeListener("Group.myMembership", this._onGroupMyMembership);
+        this.context.removeListener("Group.myMembership", this.onGroupMyMembership);
-        this.context.removeListener("sync", this._onClientSync);
+        this.context.removeListener("sync", this.onClientSync);
-        if (this._groupFilterOrderStoreToken) {
+        if (this.groupFilterOrderStoreToken) {
-            this._groupFilterOrderStoreToken.remove();
+            this.groupFilterOrderStoreToken.remove();
         }
+        UIStore.instance.stopTrackingElementDimensions("GroupPanel");
     }
 
-    _onGroupMyMembership = () => {
+    private onGroupMyMembership = () => {
         if (this.unmounted) return;
         dis.dispatch(GroupActions.fetchJoinedGroups(this.context));
     };
 
-    _onClientSync = (syncState, prevState) => {
+    private onClientSync = (syncState, prevState) => {
         // Consider the client reconnected if there is no error with syncing.
         // This means the state could be RECONNECTING, SYNCING, PREPARED or CATCHUP.
         const reconnected = syncState !== "ERROR" && prevState !== syncState;
@@ -82,18 +106,18 @@ class GroupFilterPanel extends React.Component {
         }
     };
 
-    onClick = e => {
+    private onClick = e => {
         // only dispatch if its not a no-op
         if (this.state.selectedTags.length > 0) {
             dis.dispatch({ action: 'deselect_tags' });
         }
     };
 
-    onClearFilterClick = ev => {
+    private onClearFilterClick = ev => {
         dis.dispatch({ action: 'deselect_tags' });
     };
 
-    renderGlobalIcon() {
+    private renderGlobalIcon() {
         if (!SettingsStore.getValue("feature_communities_v2_prototypes")) return null;
 
         return (
@@ -104,7 +128,7 @@ class GroupFilterPanel extends React.Component {
         );
     }
 
-    render() {
+    public render() {
         const DNDTagTile = sdk.getComponent('elements.DNDTagTile');
         const ActionButton = sdk.getComponent('elements.ActionButton');
 
@@ -147,7 +171,7 @@ class GroupFilterPanel extends React.Component {
             );
         }
 
-        return <div className={classes} onClick={this.onClearFilterClick}>
+        return <div className={classes} onClick={this.onClearFilterClick} ref={this.ref}>
             <AutoHideScrollbar
                 className="mx_GroupFilterPanel_scroller"
                 onClick={this.onClick}

src/components/structures/LeftPanel.tsx

@@ -37,11 +37,9 @@ import SettingsStore from "../../settings/SettingsStore";
 import RoomListStore, { LISTS_UPDATE_EVENT } from "../../stores/room-list/RoomListStore";
 import IndicatorScrollbar from "../structures/IndicatorScrollbar";
 import AccessibleTooltipButton from "../views/elements/AccessibleTooltipButton";
-import { OwnProfileStore } from "../../stores/OwnProfileStore";
 import RoomListNumResults from "../views/rooms/RoomListNumResults";
 import LeftPanelWidget from "./LeftPanelWidget";
 import { replaceableComponent } from "../../utils/replaceableComponent";
-import { mediaFromMxc } from "../../customisations/Media";
 import SpaceStore, { UPDATE_SELECTED_SPACE } from "../../stores/SpaceStore";
 import { getKeyBindingsManager, RoomListAction } from "../../KeyBindingsManager";
 import UIStore from "../../stores/UIStore";
@@ -71,6 +69,7 @@ export default class LeftPanel extends React.Component<IProps, IState> {
     private ref: React.RefObject<HTMLDivElement> = createRef();
     private listContainerRef: React.RefObject<HTMLDivElement> = createRef();
     private groupFilterPanelWatcherRef: string;
+    private groupFilterPanelContainer = createRef<HTMLDivElement>();
     private bgImageWatcherRef: string;
     private focusedElement = null;
     private isDoingStickyHeaders = false;
@@ -86,17 +85,19 @@ export default class LeftPanel extends React.Component<IProps, IState> {
 
         BreadcrumbsStore.instance.on(UPDATE_EVENT, this.onBreadcrumbsUpdate);
         RoomListStore.instance.on(LISTS_UPDATE_EVENT, this.onBreadcrumbsUpdate);
-        OwnProfileStore.instance.on(UPDATE_EVENT, this.onBackgroundImageUpdate);
         SpaceStore.instance.on(UPDATE_SELECTED_SPACE, this.updateActiveSpace);
-        this.bgImageWatcherRef = SettingsStore.watchSetting(
-            "RoomList.backgroundImage", null, this.onBackgroundImageUpdate);
         this.groupFilterPanelWatcherRef = SettingsStore.watchSetting("TagPanel.enableTagPanel", null, () => {
             this.setState({ showGroupFilterPanel: SettingsStore.getValue("TagPanel.enableTagPanel") });
         });
     }
 
     public componentDidMount() {
+        UIStore.instance.trackElementDimensions("LeftPanel", this.ref.current);
         UIStore.instance.trackElementDimensions("ListContainer", this.listContainerRef.current);
+        if (this.groupFilterPanelContainer.current) {
+            const componentName = "GroupFilterPanelContainer";
+            UIStore.instance.trackElementDimensions(componentName, this.groupFilterPanelContainer.current);
+        }
         UIStore.instance.on("ListContainer", this.refreshStickyHeaders);
         // Using the passive option to not block the main thread
         // https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#improving_scrolling_performance_with_passive_listeners
@@ -105,10 +106,8 @@ export default class LeftPanel extends React.Component<IProps, IState> {
 
     public componentWillUnmount() {
         SettingsStore.unwatchSetting(this.groupFilterPanelWatcherRef);
-        SettingsStore.unwatchSetting(this.bgImageWatcherRef);
         BreadcrumbsStore.instance.off(UPDATE_EVENT, this.onBreadcrumbsUpdate);
         RoomListStore.instance.off(LISTS_UPDATE_EVENT, this.onBreadcrumbsUpdate);
-        OwnProfileStore.instance.off(UPDATE_EVENT, this.onBackgroundImageUpdate);
         SpaceStore.instance.off(UPDATE_SELECTED_SPACE, this.updateActiveSpace);
         UIStore.instance.stopTrackingElementDimensions("ListContainer");
         UIStore.instance.removeListener("ListContainer", this.refreshStickyHeaders);
@@ -149,23 +148,6 @@ export default class LeftPanel extends React.Component<IProps, IState> {
         }
     };
 
-    private onBackgroundImageUpdate = () => {
-        // Note: we do this in the LeftPanel as it uses this variable most prominently.
-        const avatarSize = 32; // arbitrary
-        let avatarUrl = OwnProfileStore.instance.getHttpAvatarUrl(avatarSize);
-        const settingBgMxc = SettingsStore.getValue("RoomList.backgroundImage");
-        if (settingBgMxc) {
-            avatarUrl = mediaFromMxc(settingBgMxc).getSquareThumbnailHttp(avatarSize);
-        }
-
-        const avatarUrlProp = `url(${avatarUrl})`;
-        if (!avatarUrl) {
-            document.body.style.removeProperty("--avatar-url");
-        } else if (document.body.style.getPropertyValue("--avatar-url") !== avatarUrlProp) {
-            document.body.style.setProperty("--avatar-url", avatarUrlProp);
-        }
-    };
-
     private handleStickyHeaders(list: HTMLDivElement) {
         if (this.isDoingStickyHeaders) return;
         this.isDoingStickyHeaders = true;
@@ -443,7 +425,7 @@ export default class LeftPanel extends React.Component<IProps, IState> {
         let leftLeftPanel;
         if (this.state.showGroupFilterPanel) {
             leftLeftPanel = (
-                <div className="mx_LeftPanel_GroupFilterPanelContainer">
+                <div className="mx_LeftPanel_GroupFilterPanelContainer" ref={this.groupFilterPanelContainer}>
                     <GroupFilterPanel />
                     { SettingsStore.getValue("feature_custom_tags") ? <CustomRoomTagPanel /> : null }
                 </div>

src/components/structures/LoggedInView.tsx

@@ -58,12 +58,16 @@ import { replaceableComponent } from "../../utils/replaceableComponent";
 import CallHandler from '../../CallHandler';
 import { MatrixCall } from 'matrix-js-sdk/src/webrtc/call';
 import AudioFeedArrayForCall from '../views/voip/AudioFeedArrayForCall';
+import { OwnProfileStore } from '../../stores/OwnProfileStore';
+import { UPDATE_EVENT } from "../../stores/AsyncStore";
 import RoomView from './RoomView';
 import ToastContainer from './ToastContainer';
 import MyGroups from "./MyGroups";
 import UserView from "./UserView";
 import GroupView from "./GroupView";
+import BackdropPanel from "./BackdropPanel";
 import SpaceStore from "../../stores/SpaceStore";
+import classNames from 'classnames';
 
 // We need to fetch each pinned message individually (if we don't already have it)
 // so each pinned message may trigger a request. Limit the number per room for sanity.
@@ -127,6 +131,7 @@ interface IState {
     usageLimitEventTs?: number;
     useCompactLayout: boolean;
     activeCalls: Array<MatrixCall>;
+    backgroundImage?: CanvasImageSource;
 }
 
 /**
@@ -193,7 +198,10 @@ class LoggedInView extends React.Component<IProps, IState> {
 
         this.resizer = this.createResizer();
         this.resizer.attach();
+
+        OwnProfileStore.instance.on(UPDATE_EVENT, this.refreshBackgroundImage);
         this.loadResizerPreferences();
+        this.refreshBackgroundImage();
     }
 
     componentWillUnmount() {
@@ -202,10 +210,17 @@ class LoggedInView extends React.Component<IProps, IState> {
         this._matrixClient.removeListener("accountData", this.onAccountData);
         this._matrixClient.removeListener("sync", this.onSync);
         this._matrixClient.removeListener("RoomState.events", this.onRoomStateEvents);
+        OwnProfileStore.instance.off(UPDATE_EVENT, this.refreshBackgroundImage);
         SettingsStore.unwatchSetting(this.compactLayoutWatcherRef);
         this.resizer.detach();
     }
 
+    private refreshBackgroundImage = async (): Promise<void> => {
+        this.setState({
+            backgroundImage: await OwnProfileStore.instance.getAvatarBitmap(),
+        });
+    };
+
     private onAction = (payload): void => {
         switch (payload.action) {
             case 'call_state': {
@@ -608,10 +623,11 @@ class LoggedInView extends React.Component<IProps, IState> {
                 break;
         }
 
-        let bodyClasses = 'mx_MatrixChat';
+        const bodyClasses = classNames({
-        if (this.state.useCompactLayout) {
+            'mx_MatrixChat': true,
-            bodyClasses += ' mx_MatrixChat_useCompactLayout';
+            'mx_MatrixChat_useCompactLayout': this.state.useCompactLayout,
-        }
+            'mx_MatrixChat--with-avatar': this.state.backgroundImage,
+        });
 
         const audioFeedArraysForCalls = this.state.activeCalls.map((call) => {
             return (
@@ -629,14 +645,17 @@ class LoggedInView extends React.Component<IProps, IState> {
                 >
                     <ToastContainer />
                     <div ref={this._resizeContainer} className={bodyClasses}>
+                        <BackdropPanel
+                            backgroundImage={this.state.backgroundImage}
+                        />
                         { SpaceStore.spacesEnabled ? <SpacePanel /> : null }
                         <LeftPanel
                             isMinimized={this.props.collapseLhs || false}
                             resizeNotifier={this.props.resizeNotifier}
                         />
                         <ResizeHandle />
-                        { pageElement }
                     </div>
+                    { pageElement }
                 </div>
                 <CallContainer />
                 <NonUrgentToastContainer />

src/components/views/spaces/SpacePanel.tsx

@@ -14,7 +14,16 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ComponentProps, Dispatch, ReactNode, SetStateAction, useEffect, useState } from "react";
+import React, {
+    ComponentProps,
+    Dispatch,
+    ReactNode,
+    SetStateAction,
+    useEffect,
+    useLayoutEffect,
+    useRef,
+    useState,
+} from "react";
 import { DragDropContext, Draggable, Droppable } from "react-beautiful-dnd";
 import classNames from "classnames";
 import { Room } from "matrix-js-sdk/src/models/room";
@@ -43,6 +52,7 @@ import IconizedContextMenu, {
 } from "../context_menus/IconizedContextMenu";
 import SettingsStore from "../../../settings/SettingsStore";
 import { SettingLevel } from "../../../settings/SettingLevel";
+import UIStore from "../../../stores/UIStore";
 
 const useSpaces = (): [Room[], Room[], Room | null] => {
     const invites = useEventEmitterState<Room[]>(SpaceStore.instance, UPDATE_INVITED_SPACES, () => {
@@ -206,6 +216,11 @@ const InnerSpacePanel = React.memo<IInnerSpacePanelProps>(({ children, isPanelCo
 
 const SpacePanel = () => {
     const [isPanelCollapsed, setPanelCollapsed] = useState(true);
+    const ref = useRef<HTMLUListElement>();
+    useLayoutEffect(() => {
+        UIStore.instance.trackElementDimensions("SpacePanel", ref.current);
+        return () => UIStore.instance.stopTrackingElementDimensions("SpacePanel");
+    }, []);
 
     const onKeyDown = (ev: React.KeyboardEvent) => {
         let handled = true;
@@ -280,6 +295,7 @@ const SpacePanel = () => {
                         onKeyDown={onKeyDownHandler}
                         role="tree"
                         aria-label={_t("Spaces")}
+                        ref={ref}
                     >
                         <Droppable droppableId="top-level-spaces">
                             { (provided, snapshot) => (

src/stores/OwnProfileStore.ts

@@ -19,10 +19,12 @@ import { AsyncStoreWithClient } from "./AsyncStoreWithClient";
 import defaultDispatcher from "../dispatcher/dispatcher";
 import { MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { User } from "matrix-js-sdk/src/models/user";
-import { throttle } from "lodash";
+import { memoize, throttle } from "lodash";
 import { MatrixClientPeg } from "../MatrixClientPeg";
 import { _t } from "../languageHandler";
 import { mediaFromMxc } from "../customisations/Media";
+import SettingsStore from "../settings/SettingsStore";
+import { getDrawable } from "../utils/drawable";
 
 interface IState {
     displayName?: string;
@@ -137,6 +139,22 @@ export class OwnProfileStore extends AsyncStoreWithClient<IState> {
         await this.updateState({ displayName: profileInfo.displayname, avatarUrl: profileInfo.avatar_url });
     };
 
+    public async getAvatarBitmap(avatarSize = 32): Promise<CanvasImageSource> {
+        let avatarUrl = this.getHttpAvatarUrl(avatarSize);
+        const settingBgMxc = SettingsStore.getValue("RoomList.backgroundImage");
+        if (settingBgMxc) {
+            avatarUrl = mediaFromMxc(settingBgMxc).getSquareThumbnailHttp(avatarSize);
+        }
+
+        if (avatarUrl) {
+            return await this.buildBitmap(avatarUrl);
+        } else {
+            return null;
+        }
+    }
+
+    private buildBitmap = memoize(getDrawable);
+
     private onStateEvents = throttle(async (ev: MatrixEvent) => {
         const myUserId = MatrixClientPeg.get().getUserId();
         if (ev.getType() === 'm.room.member' && ev.getSender() === myUserId && ev.getStateKey() === myUserId) {

src/utils/drawable.ts

@@ -0,0 +1,36 @@
+/*
+Copyright 2021 New Vector Ltd
+
+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.
+*/
+
+/**
+ * Fetch an image using the best available method based on browser compatibility
+ * @param url the URL of the image to fetch
+ * @returns a canvas drawable object
+ */
+export async function getDrawable(url: string): Promise<CanvasImageSource> {
+    if ('createImageBitmap' in window) {
+        const response = await fetch(url);
+        const blob = await response.blob();
+        return await createImageBitmap(blob);
+    } else {
+        return new Promise<HTMLImageElement>((resolve, reject) => {
+            const img = document.createElement("img");
+            img.crossOrigin = "anonymous";
+            img.onload = () => resolve(img);
+            img.onerror = (e) => reject(e);
+            img.src = url;
+        });
+    }
+}

yarn.lock

@@ -2917,6 +2917,11 @@ content-type@^1.0.4:
   resolved "https://registry.yarnpkg.com/content-type/-/content-type-1.0.4.tgz#e138cc75e040c727b1966fe5e5f8c9aee256fe3b"
   integrity sha512-hIP3EEPs8tB9AT1L+NUqtwOAps4mk2Zob89MWXMHjHWg9milF/j4osnnQLXBCBFBk/tvIG/tUc9mOUJiPBhPXA==
 
+context-filter-polyfill@^0.2.4:
+  version "0.2.4"
+  resolved "https://registry.yarnpkg.com/context-filter-polyfill/-/context-filter-polyfill-0.2.4.tgz#ecf88d3197e7c3a47e9a7ae2d5167b703945a5d4"
+  integrity sha512-LDZ3WiTzo6kIeJM7j8kPSgZf+gbD1cV1GaLyYO8RWvAg25cO3zUo3d2KizO0w9hAezNwz7tTbuWKpPdvLWzKqQ==
+
 convert-source-map@^1.1.0, convert-source-map@^1.4.0, convert-source-map@^1.6.0, convert-source-map@^1.7.0:
   version "1.8.0"
   resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-1.8.0.tgz#f3373c32d21b4d780dd8004514684fb791ca4369"