Make themed widgets reflect the effective theme

So that widgets such as Element Call will show up in the right theme even if the app is set to match the system theme.

Author: robintown

src/components/structures/MatrixChat.tsx

@@ -50,7 +50,7 @@ import ThemeController from "../../settings/controllers/ThemeController";
 import { startAnyRegistrationFlow } from "../../Registration";
 import ResizeNotifier from "../../utils/ResizeNotifier";
 import AutoDiscoveryUtils from "../../utils/AutoDiscoveryUtils";
-import ThemeWatcher from "../../settings/watchers/ThemeWatcher";
+import ThemeWatcher, { ThemeWatcherEvent } from "../../settings/watchers/ThemeWatcher";
 import { FontWatcher } from "../../settings/watchers/FontWatcher";
 import { storeRoomAliasInCache } from "../../RoomAliasCache";
 import ToastStore from "../../stores/ToastStore";
@@ -133,6 +133,7 @@ import { ConfirmSessionLockTheftView } from "./auth/ConfirmSessionLockTheftView"
 import { LoginSplashView } from "./auth/LoginSplashView";
 import { cleanUpDraftsIfRequired } from "../../DraftCleaner";
 import { InitialCryptoSetupStore } from "../../stores/InitialCryptoSetupStore";
+import { setTheme } from "../../theme";
 
 // legacy export
 export { default as Views } from "../../Views";
@@ -467,6 +468,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         this.themeWatcher = new ThemeWatcher();
         this.fontWatcher = new FontWatcher();
         this.themeWatcher.start();
+        this.themeWatcher.on(ThemeWatcherEvent.Change, setTheme);
         this.fontWatcher.start();
 
         initSentry(SdkConfig.get("sentry"));
@@ -499,6 +501,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     public componentWillUnmount(): void {
         Lifecycle.stopMatrixClient();
         dis.unregister(this.dispatcherRef);
+        this.themeWatcher?.off(ThemeWatcherEvent.Change, setTheme);
         this.themeWatcher?.stop();
         this.fontWatcher?.stop();
         UIStore.destroy();

src/components/views/dialogs/ModalWidgetDialog.tsx

@@ -33,7 +33,7 @@ import { OwnProfileStore } from "../../../stores/OwnProfileStore";
 import { arrayFastClone } from "../../../utils/arrays";
 import { ElementWidget } from "../../../stores/widgets/StopGapWidget";
 import { ELEMENT_CLIENT_ID } from "../../../identifiers";
-import SettingsStore from "../../../settings/SettingsStore";
+import ThemeWatcher, { ThemeWatcherEvent } from "../../../settings/watchers/ThemeWatcher";
 
 interface IProps {
     widgetDefinition: IModalWidgetOpenRequestData;
@@ -54,6 +54,7 @@ export default class ModalWidgetDialog extends React.PureComponent<IProps, IStat
     private readonly widget: Widget;
     private readonly possibleButtons: ModalButtonID[];
     private appFrame: React.RefObject<HTMLIFrameElement> = React.createRef();
+    private readonly themeWatcher = new ThemeWatcher();
 
     public state: IState = {
         disabledButtonIds: (this.props.widgetDefinition.buttons || []).filter((b) => b.disabled).map((b) => b.id),
@@ -77,13 +78,19 @@ export default class ModalWidgetDialog extends React.PureComponent<IProps, IStat
     }
 
     public componentWillUnmount(): void {
+        this.themeWatcher.off(ThemeWatcherEvent.Change, this.onThemeChange);
+        this.themeWatcher.stop();
         if (!this.state.messaging) return;
         this.state.messaging.off("ready", this.onReady);
         this.state.messaging.off(`action:${WidgetApiFromWidgetAction.CloseModalWidget}`, this.onWidgetClose);
         this.state.messaging.stop();
     }
 
     private onReady = (): void => {
+        this.themeWatcher.start();
+        this.themeWatcher.on(ThemeWatcherEvent.Change, this.onThemeChange);
+        // Theme may have changed while messaging was starting
+        this.onThemeChange(this.themeWatcher.getEffectiveTheme());
         this.state.messaging?.sendWidgetConfig(this.props.widgetDefinition);
     };
 
@@ -94,6 +101,10 @@ export default class ModalWidgetDialog extends React.PureComponent<IProps, IStat
         this.state.messaging.on(`action:${WidgetApiFromWidgetAction.SetModalButtonEnabled}`, this.onButtonEnableToggle);
     };
 
+    private onThemeChange = (theme: string): void => {
+        this.state.messaging?.updateTheme({ name: theme });
+    };
+
     private onWidgetClose = (ev: CustomEvent<IModalWidgetCloseRequest>): void => {
         this.props.onFinished(true, ev.detail.data);
     };
@@ -127,7 +138,7 @@ export default class ModalWidgetDialog extends React.PureComponent<IProps, IStat
             userDisplayName: OwnProfileStore.instance.displayName ?? undefined,
             userHttpAvatarUrl: OwnProfileStore.instance.getHttpAvatarUrl() ?? undefined,
             clientId: ELEMENT_CLIENT_ID,
-            clientTheme: SettingsStore.getValue("theme"),
+            clientTheme: this.themeWatcher.getEffectiveTheme(),
             clientLanguage: getUserLanguage(),
             baseUrl: MatrixClientPeg.safeGet().baseUrl,
         });

src/settings/watchers/ThemeWatcher.ts

@@ -8,16 +8,25 @@ Please see LICENSE files in the repository root for full details.
 */
 
 import { logger } from "matrix-js-sdk/src/logger";
+import { TypedEventEmitter } from "matrix-js-sdk/src/matrix";
 
 import SettingsStore from "../SettingsStore";
 import dis from "../../dispatcher/dispatcher";
 import { Action } from "../../dispatcher/actions";
 import ThemeController from "../controllers/ThemeController";
-import { findHighContrastTheme, setTheme } from "../../theme";
+import { findHighContrastTheme } from "../../theme";
 import { ActionPayload } from "../../dispatcher/payloads";
 import { SettingLevel } from "../SettingLevel";
 
-export default class ThemeWatcher {
+export enum ThemeWatcherEvent {
+    Change = "change",
+}
+
+interface ThemeWatcherEventHandlerMap {
+    [ThemeWatcherEvent.Change]: (theme: string) => void;
+}
+
+export default class ThemeWatcher extends TypedEventEmitter<ThemeWatcherEvent, ThemeWatcherEventHandlerMap> {
     private themeWatchRef?: string;
     private systemThemeWatchRef?: string;
     private dispatcherRef?: string;
@@ -29,6 +38,7 @@ export default class ThemeWatcher {
     private currentTheme: string;
 
     public constructor() {
+        super();
         // we have both here as each may either match or not match, so by having both
         // we can get the tristate of dark/light/unsupported
         this.preferDark = (<any>global).matchMedia("(prefers-color-scheme: dark)");
@@ -72,9 +82,7 @@ export default class ThemeWatcher {
     public recheck(forceTheme?: string): void {
         const oldTheme = this.currentTheme;
         this.currentTheme = forceTheme === undefined ? this.getEffectiveTheme() : forceTheme;
-        if (oldTheme !== this.currentTheme) {
-            setTheme(this.currentTheme);
-        }
+        if (oldTheme !== this.currentTheme) this.emit(ThemeWatcherEvent.Change, this.currentTheme);
     }
 
     public getEffectiveTheme(): string {

src/stores/widgets/StopGapWidget.ts

@@ -37,7 +37,6 @@ import { MatrixClientPeg } from "../../MatrixClientPeg";
 import { OwnProfileStore } from "../OwnProfileStore";
 import WidgetUtils from "../../utils/WidgetUtils";
 import { IntegrationManagers } from "../../integrations/IntegrationManagers";
-import SettingsStore from "../../settings/SettingsStore";
 import { WidgetType } from "../../widgets/WidgetType";
 import ActiveWidgetStore from "../ActiveWidgetStore";
 import { objectShallowClone } from "../../utils/objects";
@@ -46,7 +45,7 @@ import { Action } from "../../dispatcher/actions";
 import { ElementWidgetActions, IHangupCallApiRequest, IViewRoomApiRequest } from "./ElementWidgetActions";
 import { ModalWidgetStore } from "../ModalWidgetStore";
 import { IApp, isAppWidget } from "../WidgetStore";
-import ThemeWatcher from "../../settings/watchers/ThemeWatcher";
+import ThemeWatcher, { ThemeWatcherEvent } from "../../settings/watchers/ThemeWatcher";
 import { getCustomTheme } from "../../theme";
 import { ElementWidgetCapabilities } from "./ElementWidgetCapabilities";
 import { ELEMENT_CLIENT_ID } from "../../identifiers";
@@ -153,6 +152,7 @@ export class StopGapWidget extends EventEmitter {
     private roomId?: string;
     private kind: WidgetKind;
     private readonly virtual: boolean;
+    private readonly themeWatcher = new ThemeWatcher();
     private readUpToMap: { [roomId: string]: string } = {}; // room ID to event ID
     // This promise will be called and needs to resolve before the widget will actually become sticky.
     private stickyPromise?: () => Promise<void>;
@@ -214,7 +214,7 @@ export class StopGapWidget extends EventEmitter {
             userDisplayName: OwnProfileStore.instance.displayName ?? undefined,
             userHttpAvatarUrl: OwnProfileStore.instance.getHttpAvatarUrl() ?? undefined,
             clientId: ELEMENT_CLIENT_ID,
-            clientTheme: SettingsStore.getValue("theme"),
+            clientTheme: this.themeWatcher.getEffectiveTheme(),
             clientLanguage: getUserLanguage(),
             deviceId: this.client.getDeviceId() ?? undefined,
             baseUrl: this.client.baseUrl,
@@ -246,6 +246,10 @@ export class StopGapWidget extends EventEmitter {
         return !!this.messaging;
     }
 
+    private onThemeChange = (theme: string): void => {
+        this.messaging?.updateTheme({ name: theme });
+    };
+
     private onOpenModal = async (ev: CustomEvent<IModalWidgetOpenRequest>): Promise<void> => {
         ev.preventDefault();
         if (ModalWidgetStore.instance.canOpenModalWidget()) {
@@ -281,6 +285,11 @@ export class StopGapWidget extends EventEmitter {
         this.messaging.on("ready", () => {
             WidgetMessagingStore.instance.storeMessaging(this.mockWidget, this.roomId, this.messaging!);
             this.emit("ready");
+
+            this.themeWatcher.start();
+            this.themeWatcher.on(ThemeWatcherEvent.Change, this.onThemeChange);
+            // Theme may have changed while messaging was starting
+            this.onThemeChange(this.themeWatcher.getEffectiveTheme());
         });
         this.messaging.on("capabilitiesNotified", () => this.emit("capabilitiesNotified"));
         this.messaging.on(`action:${WidgetApiFromWidgetAction.OpenModalWidget}`, this.onOpenModal);