Merge pull request #178 from vector-im/bwindels/lightbox

Lightbox for picture messages

src/domain/navigation/index.js

@@ -36,6 +36,8 @@ function allowsChild(parent, child) {
         case "rooms":
             // downside of the approach: both of these will control which tile is selected
             return type === "room" || type === "empty-grid-tile";
+        case "room":
+            return type === "lightbox";
         default:
             return false;
     }

src/domain/session/SessionViewModel.js

@@ -17,6 +17,7 @@ limitations under the License.
 
 import {LeftPanelViewModel} from "./leftpanel/LeftPanelViewModel.js";
 import {RoomViewModel} from "./room/RoomViewModel.js";
+import {LightboxViewModel} from "./room/LightboxViewModel.js";
 import {SessionStatusViewModel} from "./SessionStatusViewModel.js";
 import {RoomGridViewModel} from "./RoomGridViewModel.js";
 import {SettingsViewModel} from "./settings/SettingsViewModel.js";
@@ -67,6 +68,12 @@ export class SessionViewModel extends ViewModel {
             this._updateSettings(settingsOpen);
         }));
         this._updateSettings(settings.get());
+
+        const lightbox = this.navigation.observe("lightbox");
+        this.track(lightbox.subscribe(eventId => {
+            this._updateLightbox(eventId);
+        }));
+        this._updateLightbox(lightbox.get());
     }
 
     get id() {
@@ -194,4 +201,20 @@ export class SessionViewModel extends ViewModel {
         }
         this.emitChange("activeSection");
     }
+
+    _updateLightbox(eventId) {
+        if (this._lightboxViewModel) {
+            this._lightboxViewModel = this.disposeTracked(this._lightboxViewModel);
+        }
+        if (eventId) {
+            const roomId = this.navigation.path.get("room").value;
+            const room = this._sessionContainer.session.rooms.get(roomId);
+            this._lightboxViewModel = this.track(new LightboxViewModel(this.childOptions({eventId, room})));
+        }
+        this.emitChange("lightboxViewModel");
+    }
+
+    get lightboxViewModel() {
+        return this._lightboxViewModel;
+    }
 }

src/domain/session/room/LightboxViewModel.js

@@ -0,0 +1,97 @@
+/*
+Copyright 2020 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 {ViewModel} from "../../ViewModel.js";
+
+export class LightboxViewModel extends ViewModel {
+    constructor(options) {
+        super(options);
+        this._eventId = options.eventId;
+        this._unencryptedImageUrl = null;
+        this._decryptedImage = null;
+        this._closeUrl = this.urlCreator.urlUntilSegment("room");
+        this._eventEntry = null;
+        this._date = null;
+        this._subscribeToEvent(options.room, options.eventId);
+    }
+
+    _subscribeToEvent(room, eventId) {
+        const eventObservable = room.observeEvent(eventId);
+        this.track(eventObservable.subscribe(eventEntry => {
+            this._loadEvent(room, eventEntry);
+        }));
+        this._loadEvent(room, eventObservable.get());
+    }
+
+    async _loadEvent(room, eventEntry) {
+        if (!eventEntry) {
+            return;
+        }
+        const {mediaRepository} = room;
+        this._eventEntry = eventEntry;
+        const {content} = this._eventEntry;
+        this._date = this._eventEntry.timestamp ? new Date(this._eventEntry.timestamp) : null;
+        if (content.url) {
+            this._unencryptedImageUrl = mediaRepository.mxcUrl(content.url);
+            this.emitChange("imageUrl");
+        } else if (content.file) {
+            this._decryptedImage = this.track(await mediaRepository.downloadEncryptedFile(content.file));
+            this.emitChange("imageUrl");
+        }
+    }
+
+    get imageWidth() {
+        return this._eventEntry?.content?.info?.w;
+    }
+
+    get imageHeight() {
+        return this._eventEntry?.content?.info?.h;
+    }
+
+    get name() {
+        return this._eventEntry?.content?.body;
+    }
+
+    get sender() {
+        return this._eventEntry?.displayName;
+    }
+
+    get imageUrl() {
+        if (this._decryptedImage) {
+            return this._decryptedImage.url;
+        } else if (this._unencryptedImageUrl) {
+            return this._unencryptedImageUrl;
+        } else {
+            return "";
+        }
+    }
+
+    get date() {
+        return this._date && this._date.toLocaleDateString({}, { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' });
+    }
+
+    get time() {
+        return this._date && this._date.toLocaleTimeString({}, {hour: "numeric", minute: "2-digit"});
+    }
+
+    get closeUrl() {
+        return this._closeUrl;
+    }
+
+    close() {
+        this.platform.history.pushUrl(this.closeUrl);
+    }
+}

src/domain/session/room/timeline/TimelineViewModel.js

@@ -43,7 +43,7 @@ export class TimelineViewModel extends ViewModel {
         // once we support sending messages we could do
         // timeline.entries.concat(timeline.pendingEvents)
         // for an ObservableList that also contains local echos
-        this._tiles = new TilesCollection(timeline.entries, tilesCreator({room, ownUserId, platform: this.platform}));
+        this._tiles = new TilesCollection(timeline.entries, tilesCreator(this.childOptions({room, ownUserId})));
     }
 
     async load() {

src/domain/session/room/timeline/tiles/GapTile.js

@@ -18,22 +18,25 @@ import {SimpleTile} from "./SimpleTile.js";
 import {UpdateAction} from "../UpdateAction.js";
 
 export class GapTile extends SimpleTile {
-    constructor(options, timeline) {
+    constructor(options) {
         super(options);
-        this._timeline = timeline;
         this._loading = false;
         this._error = null;
     }
 
+    get _room() {
+        return this.getOption("room");
+    }
+
     async fill() {
         // prevent doing this twice
         if (!this._loading) {
             this._loading = true;
             this.emitChange("isLoading");
             try {
-                await this._timeline.fillGap(this._entry, 10);
+                await this._room.fillGap(this._entry, 10);
             } catch (err) {
-                console.error(`timeline.fillGap(): ${err.message}:\n${err.stack}`);
+                console.error(`room.fillGap(): ${err.message}:\n${err.stack}`);
                 this._error = err;
                 this.emitChange("error");
                 // rethrow so caller of this method

src/domain/session/room/timeline/tiles/ImageTile.js

@@ -27,14 +27,20 @@ export class ImageTile extends MessageTile {
         this._decryptedImage = null;
         this._error = null;
         this.load();
+        this._lightboxUrl = this.urlCreator.urlForSegments([
+            // ensure the right room is active if in grid view
+            this.navigation.segment("room", this._room.id),
+            this.navigation.segment("lightbox", this._entry.id)
+        ]);
     }
 
     async _loadEncryptedFile(file) {
-        const buffer = await this._mediaRepository.downloadEncryptedFile(file);
+        const bufferHandle = await this._mediaRepository.downloadEncryptedFile(file);
         if (this.isDisposed) {
+            bufferHandle.dispose();
             return;
         }
-        return this.track(this.platform.createBufferURL(buffer, file.mimetype));
+        return this.track(bufferHandle);
     }
 
     async load() {
@@ -54,6 +60,10 @@ export class ImageTile extends MessageTile {
         }
     }
 
+    get lightboxUrl() {
+        return this._lightboxUrl;
+    }
+
     get thumbnailUrl() {
         if (this._decryptedThumbail) {
             return this._decryptedThumbail.url;

src/domain/session/room/timeline/tiles/MessageTile.js

@@ -20,12 +20,19 @@ import {getIdentifierColorNumber, avatarInitials} from "../../../../avatar.js";
 export class MessageTile extends SimpleTile {
     constructor(options) {
         super(options);
-        this._mediaRepository = options.mediaRepository;
         this._isOwn = this._entry.sender === options.ownUserId;
         this._date = this._entry.timestamp ? new Date(this._entry.timestamp) : null;
         this._isContinuation = false;
     }
 
+    get _room() {
+        return this.getOption("room");
+    }
+
+    get _mediaRepository() {
+        return this._room.mediaRepository;
+    }
+
     get shape() {
         return "message";
     }

src/domain/session/room/timeline/tilesCreator.js

@@ -23,12 +23,11 @@ import {RoomMemberTile} from "./tiles/RoomMemberTile.js";
 import {EncryptedEventTile} from "./tiles/EncryptedEventTile.js";
 import {EncryptionEnabledTile} from "./tiles/EncryptionEnabledTile.js";
 
-export function tilesCreator({room, ownUserId, platform}) {
+export function tilesCreator(baseOptions) {
     return function tilesCreator(entry, emitUpdate) {
-        const options = {entry, emitUpdate, ownUserId, platform,
-            mediaRepository: room.mediaRepository};
+        const options = Object.assign({entry, emitUpdate}, baseOptions);
         if (entry.isGap) {
-            return new GapTile(options, room);
+            return new GapTile(options);
         } else if (entry.eventType) {
             switch (entry.eventType) {
                 case "m.room.message": {

src/matrix/SessionContainer.js

@@ -167,8 +167,7 @@ export class SessionContainer {
         this._requestScheduler.start();
         const mediaRepository = new MediaRepository({
             homeServer: sessionInfo.homeServer,
-            crypto: this._platform.crypto,
-            request: this._platform.request,
+            platform: this._platform,
         });
         this._session = new Session({
             storage: this._storage,

src/matrix/Sync.js

@@ -200,7 +200,7 @@ export class Sync {
                 syncTxn.abort();
             } catch (abortErr) {
                 console.error("Could not abort sync transaction, the sync response was probably only partially written and may have put storage in a inconsistent state.", abortErr);
-            } 
+            }
             throw err;
         }
         try {

src/matrix/net/MediaRepository.js

@@ -18,10 +18,9 @@ import {encodeQueryParams} from "./common.js";
 import {decryptAttachment} from "../e2ee/attachment.js";
 
 export class MediaRepository {
-    constructor({homeServer, crypto, request}) {
+    constructor({homeServer, platform}) {
         this._homeServer = homeServer;
-        this._crypto = crypto;
-        this._request = request;
+        this._platform = platform;
     }
 
     mxcUrlThumbnail(url, width, height, method) {
@@ -55,8 +54,8 @@ export class MediaRepository {
 
     async downloadEncryptedFile(fileEntry) {
         const url = this.mxcUrl(fileEntry.url);
-        const {body: encryptedBuffer} = await this._request(url, {method: "GET", format: "buffer", cache: true}).response();
-        const decryptedBuffer = await decryptAttachment(this._crypto, encryptedBuffer, fileEntry);
-        return decryptedBuffer;
+        const {body: encryptedBuffer} = await this._platform.request(url, {method: "GET", format: "buffer", cache: true}).response();
+        const decryptedBuffer = await decryptAttachment(this._platform.crypto, encryptedBuffer, fileEntry);
+        return this._platform.createBufferHandle(decryptedBuffer, fileEntry.mimetype);
     }
 }

src/matrix/room/ObservedEventMap.js

@@ -0,0 +1,90 @@
+/*
+Copyright 2020 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 {BaseObservableValue} from "../../observable/ObservableValue.js";
+
+export class ObservedEventMap {
+    constructor(notifyEmpty) {
+        this._map = new Map();
+        this._notifyEmpty = notifyEmpty;
+    }
+
+    observe(eventId, eventEntry = null) {
+        let observable = this._map.get(eventId);
+        if (!observable) {
+            observable = new ObservedEvent(this, eventEntry);
+            this._map.set(eventId, observable);
+        }
+        return observable;
+    }
+
+    updateEvents(eventEntries) {
+        for (let i = 0; i < eventEntries.length; i += 1) {
+            const entry = eventEntries[i];
+            const observable = this._map.get(entry.id);
+            observable?.update(entry);
+        }
+    }
+
+    _remove(observable) {
+        this._map.delete(observable.get().id);
+        if (this._map.size === 0) {
+            this._notifyEmpty();
+        }
+    }
+}
+
+class ObservedEvent extends BaseObservableValue {
+    constructor(eventMap, entry) {
+        super();
+        this._eventMap = eventMap;
+        this._entry = entry;
+        // remove subscription in microtask after creating it
+        // otherwise ObservedEvents would easily never get
+        // removed if you never subscribe
+        Promise.resolve().then(() => {
+            if (!this.hasSubscriptions) {
+                this._eventMap.remove(this);
+                this._eventMap = null;
+            }
+        });
+    }
+
+    subscribe(handler) {
+        if (!this._eventMap) {
+            throw new Error("ObservedEvent expired, subscribe right after calling room.observeEvent()");
+        }
+        return super.subscribe(handler);
+    }
+
+    onUnsubscribeLast() {
+        this._eventMap._remove(this);
+        this._eventMap = null;
+        super.onUnsubscribeLast();
+    }
+
+    update(entry) {
+        // entries are mostly updated in-place,
+        // apart from when they are created,
+        // but doesn't hurt to reassign
+        this._entry = entry;
+        this.emit(this._entry);
+    }
+
+    get() {
+        return this._entry;
+    }
+}

src/matrix/room/Room.js

@@ -29,8 +29,8 @@ import {Heroes} from "./members/Heroes.js";
 import {EventEntry} from "./timeline/entries/EventEntry.js";
 import {EventKey} from "./timeline/EventKey.js";
 import {Direction} from "./timeline/Direction.js";
+import {ObservedEventMap} from "./ObservedEventMap.js";
 import {DecryptionSource} from "../e2ee/common.js";
-
 const EVENT_ENCRYPTED_TYPE = "m.room.encrypted";
 
 export class Room extends EventEmitter {
@@ -53,6 +53,7 @@ export class Room extends EventEmitter {
         this._roomEncryption = null;
         this._getSyncToken = getSyncToken;
         this._clock = clock;
+        this._observedEvents = null;
     }
 
     _readRetryDecryptCandidateEntries(sinceEventKey, txn) {
@@ -165,6 +166,9 @@ export class Room extends EventEmitter {
             }
             await writeTxn.complete();
             decryption.applyToEntries(entries);
+            if (this._observedEvents) {
+                this._observedEvents.updateEvents(entries);
+            }
         });
         return request;
     }
@@ -285,6 +289,9 @@ export class Room extends EventEmitter {
         if (this._timeline) {
             this._timeline.appendLiveEntries(newTimelineEntries);
         }
+        if (this._observedEvents) {
+            this._observedEvents.updateEvents(newTimelineEntries);
+        }
         if (removedPendingEvents) {
             this._sendQueue.emitRemovals(removedPendingEvents);
         }
@@ -580,6 +587,45 @@ export class Room extends EventEmitter {
         this._summary.applyChanges(changes);
     }
 
+    observeEvent(eventId) {
+        if (!this._observedEvents) {
+            this._observedEvents = new ObservedEventMap(() => {
+                this._observedEvents = null;
+            });
+        }
+        let entry = null;
+        if (this._timeline) {
+            entry = this._timeline.getByEventId(eventId);
+        }
+        const observable = this._observedEvents.observe(eventId, entry);
+        if (!entry) {
+            // update in the background
+            this._readEventById(eventId).then(entry => {
+                observable.update(entry);
+            }).catch(err => {
+                console.warn(`could not load event ${eventId} from storage`, err);
+            });
+        }
+        return observable;
+    }
+
+    async _readEventById(eventId) {
+        let stores = [this._storage.storeNames.timelineEvents];
+        if (this.isEncrypted) {
+            stores.push(this._storage.storeNames.inboundGroupSessions);
+        }
+        const txn = this._storage.readTxn(stores);
+        const storageEntry = await txn.timelineEvents.getByEventId(this._roomId, eventId);
+        if (storageEntry) {
+            const entry = new EventEntry(storageEntry, this._fragmentIdComparer);
+            if (entry.eventType === EVENT_ENCRYPTED_TYPE) {
+                const request = this._decryptEntries(DecryptionSource.Timeline, [entry], txn);
+                await request.complete();
+            }
+            return entry;
+        }
+    }
+
     dispose() {
         this._roomEncryption?.dispose();
         this._timeline?.dispose();

src/matrix/room/timeline/Timeline.js

@@ -95,6 +95,15 @@ export class Timeline {
         }
     }
 
+    getByEventId(eventId) {
+        for (let i = 0; i < this._remoteEntries.length; i += 1) {
+            const entry = this._remoteEntries.get(i);
+            if (entry.id === eventId) {
+                return entry;
+            }
+        }
+    }
+
     /** @public */
     get entries() {
         return this._allEntries;

src/observable/BaseObservable.js

@@ -48,6 +48,10 @@ export class BaseObservable {
         return null;
     }
 
+    get hasSubscriptions() {
+        return this._handlers.size !== 0;
+    }
+
     // Add iterator over handlers here
 }
 

src/platform/web/Platform.js

@@ -27,7 +27,7 @@ import {OnlineStatus} from "./dom/OnlineStatus.js";
 import {Crypto} from "./dom/Crypto.js";
 import {estimateStorageUsage} from "./dom/StorageEstimate.js";
 import {WorkerPool} from "./dom/WorkerPool.js";
-import {BufferURL} from "./dom/BufferURL.js";
+import {BufferHandle} from "./dom/BufferHandle.js";
 
 function addScript(src) {
     return new Promise(function (resolve, reject) {
@@ -99,6 +99,8 @@ export class Platform {
         } else {
             this.request = xhrRequest;
         }
+        const isIE11 = !!window.MSInputMethodContext && !!document.documentMode;
+        this.isIE11 = isIE11;    
     }
 
     get updateService() {
@@ -116,8 +118,7 @@ export class Platform {
     }
 
     createAndMountRootView(vm) {
-        const isIE11 = !!window.MSInputMethodContext && !!document.documentMode;
-        if (isIE11) {
+        if (this.isIE11) {
             this._container.className += " legacy";
         }
         window.__hydrogenViewModel = vm;
@@ -129,7 +130,7 @@ export class Platform {
         this._serviceWorkerHandler?.setNavigation(navigation);
     }
 
-    createBufferURL(buffer, mimetype) {
-        return new BufferURL(buffer, mimetype);
+    createBufferHandle(buffer, mimetype) {
+        return new BufferHandle(buffer, mimetype);
     }
 }

src/platform/web/dom/BufferHandle.js

@@ -69,18 +69,27 @@ const ALLOWED_BLOB_MIMETYPES = {
     'audio/x-flac': true,
 };
 
-export class BufferURL {
+export class BufferHandle {
     constructor(buffer, mimetype) {
         mimetype = mimetype ? mimetype.split(";")[0].trim() : '';
         if (!ALLOWED_BLOB_MIMETYPES[mimetype]) {
             mimetype = 'application/octet-stream';
         }
-        const blob = new Blob([buffer], {type: mimetype});
-        this.url = URL.createObjectURL(blob);
+        this.blob = new Blob([buffer], {type: mimetype});
+        this._url = null;
+    }
+
+    get url() {
+        if (!this._url) {
+             this._url = URL.createObjectURL(this.blob);
+        }
+        return this._url;
     }
 
     dispose() {
-        URL.revokeObjectURL(this.url);
-        this.url = null;
+        if (this._url) {
+            URL.revokeObjectURL(this._url);
+            this._url = null;
+        }
     }
 }

src/platform/web/ui/css/layout.css

@@ -19,6 +19,11 @@ html {
     height: 100%;
 }
 
+/* unknown element in IE11 that defaults to inline */
+main {
+    display: block;
+}
+
 @media screen and (min-width: 600px) {
     .PreSessionScreen {
         width: 600px;
@@ -34,46 +39,60 @@ html {
 }
 
 .SessionView {
-    display: flex;
-    flex-direction: column;
     /* this takes into account whether or not the url bar is hidden on mobile
     (have tested Firefox Android and Safari on iOS),
     see https://developers.google.com/web/updates/2016/12/url-bar-resizing */
     position: fixed;
     height: 100%;
-}
-
-.SessionView > .main {
-    flex: 1;
-    display: flex;
+    width: 100%;
+    display: grid;
+    grid-template:
+        "status status" auto
+        "left   middle" 1fr /
+        300px   1fr;
     min-height: 0;
     min-width: 0;
-    width: 100vw;
 }
 
 /* hide back button in middle section by default */
 .middle .close-middle { display: none; }
 /* mobile layout */
 @media screen and (max-width: 800px) {
+    .SessionView:not(.middle-shown) {
+        grid-template:
+            "status" auto
+            "left" 1fr /
+            1fr;
+    }
+
+    .SessionView.middle-shown {
+        grid-template:
+            "status" auto
+            "middle" 1fr /
+            1fr;
+    }
+
+    .SessionView:not(.middle-shown) .room-placeholder { display: none; }
+    .SessionView.middle-shown .LeftPanel { display: none; }
+
     /* show back button */
     .middle .close-middle { display: block !important; }
     /* hide grid button */
     .LeftPanel .grid { display: none !important; }
-    div.middle, div.room-placeholder { display: none; }
-    div.LeftPanel {flex-grow: 1;}
-    div.middle-shown div.middle { display: flex; }
-    div.middle-shown div.LeftPanel { display: none; }
-    div.right-shown div.TimelinePanel { display: none; }
 }
 
 .LeftPanel {
-    flex: 0 0 300px;
+    grid-area: left;
     min-width: 0;
 }
 
 .room-placeholder, .middle {
-    flex: 1 0 0;
     min-width: 0;
+    grid-area: middle;
+    /* when room view is inside of a grid,
+    grid-area middle won't be found,
+    so set width manually */
+    width: 100%;
 }
 
 .RoomView {
@@ -81,6 +100,19 @@ html {
     display: flex;
 }
 
+.SessionStatusView {
+    grid-area: status;
+}
+
+.lightbox {
+    /* cover left and middle panel, not status view
+    use numeric positions because named grid areas
+    are not present in mobile layout */
+    grid-area: 2 / 1 / 3 / 3;
+    /* this should not be necessary, but chrome seems to have a bug when there are scrollbars in other grid items,
+    it seems to put the scroll areas on top of the other grid items unless they have a z-index */
+    z-index: 1;
+}
 
 .TimelinePanel {
     flex: 3;

src/platform/web/ui/css/themes/element/theme.css

@@ -494,6 +494,8 @@ ul.Timeline > li.messageStatus .message-container > p {
 .message-container {
     padding: 1px 10px 0px 10px;
     margin: 5px 10px 0 10px;
+    /* so the .picture can grow horizontally and its spacer can grow vertically */
+    width: 100%;
 }
 
 .message-container .profile {
@@ -505,9 +507,8 @@ ul.Timeline > li.messageStatus .message-container > p {
     --avatar-size: 25px;
 }
 
-.message-container img.picture {
-    margin-top: 4px;
-    border-radius: 4px;
+.TextMessageView {
+    width: 100%;
 }
 
 .TextMessageView.continuation .message-container {
@@ -538,6 +539,46 @@ ul.Timeline > li.messageStatus .message-container > p {
     color: #aaa;
 }
 
+
+.message-container .picture {
+    display: grid;
+    text-decoration: none;
+    margin-top: 4px;
+    width: 100%;
+}
+
+/* .spacer grows with an inline padding-top to the size of the image,
+so the timeline doesn't jump when the image loads */
+.message-container .picture > * {
+    grid-row: 1;
+    grid-column: 1;
+}
+
+.message-container .picture > img {
+    width: 100%;
+    height: auto;
+    /* for IE11 to still scale even though the spacer is too tall */
+    align-self: start;
+    border-radius: 4px;
+}
+
+.message-container .picture > time {
+    align-self: end;
+    justify-self: end;
+    color: #2e2f32;
+    display: block;
+    padding: 2px;
+    margin: 4px;
+    background-color: rgba(255, 255, 255, 0.75);
+    border-radius: 4px;
+}
+.message-container .picture > .spacer {
+    /* TODO: can we implement this with a pseudo element? or perhaps they are not grid items? */
+    width: 100%;
+    /* don't stretch height as it is a spacer, just in case it doesn't match with image height */
+    align-self: start;
+}
+
 .TextMessageView.pending .message-container {
     color: #ccc;
 }
@@ -632,3 +673,72 @@ button.link {
     color: #03B381;
     font-weight: 600;
 }
+
+.lightbox {
+    background-color: rgba(0,0,0,0.75);
+    display: grid;
+    grid-template:
+        "content close"   auto
+        "content details" 1fr /
+        1fr      auto;
+    color: white;
+    padding: 4px;
+}
+
+@media (max-aspect-ratio: 1/1) {
+    .lightbox {
+        grid-template:
+            "close"   auto
+            "content" 1fr
+            "details" auto /
+            1fr;
+    }
+
+    .lightbox .details {
+        width: 100% !important;
+    }
+}
+
+.lightbox .picture {
+    grid-area: content;
+    background-size: contain;
+    background-position: center;
+    background-repeat: no-repeat;
+    width: 100%;
+    height: 100%;
+    align-self: center;
+    justify-self: center;
+}
+
+.lightbox .loading {
+    grid-area: content;
+    align-self: center;
+    justify-self: center;
+    display: flex;
+}
+
+.lightbox .loading > :not(:first-child) {
+    margin-left: 8px;
+}
+
+.lightbox .close {
+    display: block;
+    grid-area: close;
+    justify-self: end;
+    background-image: url('icons/dismiss.svg');
+    background-position: center;
+    background-size: 16px;
+    background-repeat: no-repeat;
+    width: 16px;
+    height: 16px;
+    padding: 12px;
+}
+
+.lightbox .details {
+    grid-area: details;
+    padding: 12px;
+    font-size: 1.5rem;
+    width: 200px;
+}
+
+

src/platform/web/ui/css/timeline.css

@@ -37,23 +37,12 @@ limitations under the License.
     margin: 5px 0;
 }
 
-.message-container a {
+.message-container .picture {
     display: block;
-    position: relative;
-    max-width: 100%;
-    /* width and padding-top set inline to maintain aspect ratio,
-    replace with css aspect-ratio once supported */
 }
 
-.message-container img.picture {
+.message-container .picture > img {
     display: block;
-    position: absolute;
-    top: 0;
-    bottom: 0;
-    left: 0;
-    right: 0;
-    width: 100%;
-    height: 100%;
 }
 
 .TextMessageView {

src/platform/web/ui/general/TemplateView.js

@@ -74,16 +74,16 @@ export class TemplateView {
 
     _attach() {
         if (this._eventListeners) {
-            for (let {node, name, fn} of this._eventListeners) {
-                node.addEventListener(name, fn);
+            for (let {node, name, fn, useCapture} of this._eventListeners) {
+                node.addEventListener(name, fn, useCapture);
             }
         }
     }
 
     _detach() {
         if (this._eventListeners) {
-            for (let {node, name, fn} of this._eventListeners) {
-                node.removeEventListener(name, fn);
+            for (let {node, name, fn, useCapture} of this._eventListeners) {
+                node.removeEventListener(name, fn, useCapture);
             }
         }
     }
@@ -132,11 +132,11 @@ export class TemplateView {
         }
     }
 
-    _addEventListener(node, name, fn) {
+    _addEventListener(node, name, fn, useCapture = false) {
         if (!this._eventListeners) {
             this._eventListeners = [];
         }
-        this._eventListeners.push({node, name, fn});
+        this._eventListeners.push({node, name, fn, useCapture});
     }
 
     _addBinding(bindingFn) {
@@ -164,6 +164,10 @@ class TemplateBuilder {
         return this._templateView._value;
     }
 
+    addEventListener(node, name, fn, useCapture = false) {
+        this._templateView._addEventListener(node, name, fn, useCapture);
+    }
+
     _addAttributeBinding(node, name, fn) {
         let prevValue = undefined;
         const binding = () => {

src/platform/web/ui/login/LoginView.js

@@ -35,7 +35,7 @@ export class LoginView extends TemplateView {
         });
         const homeserver = t.input({
             id: "homeserver",
-            type: "text",
+            type: "url",
             placeholder: vm.i18n`Your matrix homeserver`,
             value: vm.defaultHomeServer, 
             disabled

src/platform/web/ui/session/SessionView.js

@@ -17,6 +17,7 @@ limitations under the License.
 
 import {LeftPanelView} from "./leftpanel/LeftPanelView.js";
 import {RoomView} from "./room/RoomView.js";
+import {LightboxView} from "./room/LightboxView.js";
 import {TemplateView} from "../general/TemplateView.js";
 import {StaticView} from "../general/StaticView.js";
 import {SessionStatusView} from "./SessionStatusView.js";
@@ -32,21 +33,20 @@ export class SessionView extends TemplateView {
             },
         }, [
             t.view(new SessionStatusView(vm.sessionStatusViewModel)),
-            t.div({className: "main"}, [
-                t.view(new LeftPanelView(vm.leftPanelViewModel)),
-                t.mapView(vm => vm.activeSection, activeSection => {
-                    switch (activeSection) {
-                        case "roomgrid":
-                            return new RoomGridView(vm.roomGridViewModel);
-                        case "placeholder":
-                            return new StaticView(t => t.div({className: "room-placeholder"}, t.h2(vm.i18n`Choose a room on the left side.`)));
-                        case "settings":
-                            return new SettingsView(vm.settingsViewModel);
-                        default: //room id
-                            return new RoomView(vm.currentRoomViewModel);
-                    }
-                })
-            ])
+            t.view(new LeftPanelView(vm.leftPanelViewModel)),
+            t.mapView(vm => vm.activeSection, activeSection => {
+                switch (activeSection) {
+                    case "roomgrid":
+                        return new RoomGridView(vm.roomGridViewModel);
+                    case "placeholder":
+                        return new StaticView(t => t.div({className: "room-placeholder"}, t.h2(vm.i18n`Choose a room on the left side.`)));
+                    case "settings":
+                        return new SettingsView(vm.settingsViewModel);
+                    default: //room id
+                        return new RoomView(vm.currentRoomViewModel);
+                }
+            }),
+            t.mapView(vm => vm.lightboxViewModel, lightboxViewModel => lightboxViewModel ? new LightboxView(lightboxViewModel) : null)
         ]);
     }
 }

src/platform/web/ui/session/room/LightboxView.js

@@ -0,0 +1,96 @@
+/*
+Copyright 2020 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 {TemplateView} from "../../general/TemplateView.js";
+import {spinner} from "../../common.js";
+
+export class LightboxView extends TemplateView {
+    render(t, vm) {
+        const close = t.a({href: vm.closeUrl, title: vm.i18n`Close`, className: "close"});
+        const image = t.div({
+            role: "img",
+            "aria-label": vm => vm.name,
+            title: vm => vm.name,
+            className: {
+                picture: true,
+                hidden: vm => !vm.imageUrl,
+            },
+            style: vm => `background-image: url('${vm.imageUrl}'); max-width: ${vm.imageWidth}px; max-height: ${vm.imageHeight}px;`
+        });
+        const loading = t.div({
+            className: {
+                loading: true,
+                hidden: vm => !!vm.imageUrl
+            }
+        }, [
+            spinner(t),
+            t.div(vm.i18n`Loading image…`)
+        ]);
+        const details = t.div({
+            className: "details"
+        }, [t.strong(vm => vm.name), t.br(), "uploaded by ", t.strong(vm => vm.sender), vm => ` at ${vm.time} on ${vm.date}.`]);
+        const dialog = t.div({
+            role: "dialog",
+            className: "lightbox",
+            onClick: evt => this.clickToClose(evt),
+            onKeydown: evt => this.closeOnEscKey(evt)
+        }, [image, loading, details, close]);
+        trapFocus(t, dialog);
+        return dialog;
+    }
+
+    clickToClose(evt) {
+        if (evt.target === this.root()) {
+            this.value.close();
+        }
+    }
+
+    closeOnEscKey(evt) {
+        if (evt.key === "Escape" || evt.key === "Esc") {
+            this.value.close();
+        }
+    }
+}
+
+function trapFocus(t, element) {
+    const elements = focusables(element);
+    const first = elements[0];
+    const last = elements[elements.length - 1];
+
+    t.addEventListener(element, "keydown", evt => {
+        if (evt.key === "Tab") {
+            if (evt.shiftKey) {
+                if (document.activeElement === first) {
+                    last.focus();
+                    evt.preventDefault();
+                }
+            } else {
+                if (document.activeElement === last) {
+                    first.focus();
+                    evt.preventDefault();
+                }
+            }
+        }
+    }, true);
+    Promise.resolve().then(() => {
+        first.focus();
+    });
+}
+
+function focusables(element) {
+    return element.querySelectorAll('a[href], button, textarea, input, select');
+}
+

src/platform/web/ui/session/room/timeline/ImageView.js

@@ -19,26 +19,31 @@ import {renderMessage} from "./common.js";
 
 export class ImageView extends TemplateView {
     render(t, vm) {
-        // replace with css aspect-ratio once supported
-        const heightRatioPercent = (vm.thumbnailHeight / vm.thumbnailWidth) * 100;
-        const image = t.img({
-            className: "picture",
-            src: vm => vm.thumbnailUrl,
-            width: vm.thumbnailWidth,
-            height: vm.thumbnailHeight,
-            loading: "lazy",
-            alt: vm => vm.label,
-            title: vm => vm.label,
-        });
-        const linkContainer = t.a({
-            style: `padding-top: ${heightRatioPercent}%; width: ${vm.thumbnailWidth}px;`
-        }, [
-            image,
+        const heightRatioPercent = (vm.thumbnailHeight / vm.thumbnailWidth) * 100; 
+        let spacerStyle = `padding-top: ${heightRatioPercent}%;`;
+        if (vm.platform.isIE11) {
+            // preserving aspect-ratio in a grid with padding percentages
+            // does not work in IE11, so we assume people won't use it
+            // with viewports narrower than 400px where thumbnails will get
+            // scaled. If they do, the thumbnail will still scale, but
+            // there will be whitespace underneath the picture
+            // An alternative would be to use position: absolute but that
+            // can slow down rendering, and was bleeding through the lightbox.
+            spacerStyle = `height: ${vm.thumbnailHeight}px`;
+        }
+        return renderMessage(t, vm, [
+            t.a({href: vm.lightboxUrl, className: "picture", style: `max-width: ${vm.thumbnailWidth}px`}, [
+                t.div({className: "spacer", style: spacerStyle}),
+                t.img({
+                    loading: "lazy",
+                    src: vm => vm.thumbnailUrl,
+                    alt: vm => vm.label,
+                    title: vm => vm.label,
+                    style: `max-width: ${vm.thumbnailWidth}px; max-height: ${vm.thumbnailHeight}px;`
+                }),
+                t.time(vm.date + " " + vm.time),
+            ]),
             t.if(vm => vm.error, t.createTemplate((t, vm) => t.p({className: "error"}, vm.error)))
         ]);
-
-        return renderMessage(t, vm,
-            [t.div(linkContainer), t.p(t.time(vm.date + " " + vm.time))]
-        );
     }
 }