Add initial support for a account data level key.

src/settings/Settings.tsx

@@ -8,7 +8,7 @@ Please see LICENSE files in the repository root for full details.
 */
 
 import React, { type ReactNode } from "react";
-import { UNSTABLE_MSC4133_EXTENDED_PROFILES } from "matrix-js-sdk/src/matrix";
+import { MediaPreviewConfig, UNSTABLE_MSC4133_EXTENDED_PROFILES } from "matrix-js-sdk/src/matrix";
 
 import { _t, _td, type TranslationKey } from "../languageHandler";
 import DeviceIsolationModeController from "./controllers/DeviceIsolationModeController.ts";
@@ -45,6 +45,7 @@ import { type Json, type JsonValue } from "../@types/json.ts";
 import { type RecentEmojiData } from "../emojipicker/recent.ts";
 import { type Assignable } from "../@types/common.ts";
 import { SortingAlgorithm } from "../stores/room-list-v3/skip-list/sorters/index.ts";
+import MediaPreviewConfigController from "./controllers/MediaPreviewConfigController.ts";
 
 export const defaultWatchManager = new WatchManager();
 
@@ -349,6 +350,7 @@ export interface Settings {
     "Electron.alwaysShowMenuBar": IBaseSetting<boolean>;
     "Electron.showTrayIcon": IBaseSetting<boolean>;
     "Electron.enableHardwareAcceleration": IBaseSetting<boolean>;
+    "mediaPreviewConfig": IBaseSetting<MediaPreviewConfig>;
 }
 
 export type SettingKey = keyof Settings;
@@ -425,6 +427,11 @@ export const SETTINGS: Settings = {
         supportedLevelsAreOrdered: true,
         default: false,
     },
+    "mediaPreviewConfig": {
+        controller: new MediaPreviewConfigController(),
+        supportedLevels: LEVELS_ROOM_OR_ACCOUNT,
+        default: MediaPreviewConfig.Private,
+    },
     "feature_report_to_moderators": {
         isFeature: true,
         labsGroup: LabGroup.Moderation,
@@ -1383,5 +1390,5 @@ export const SETTINGS: Settings = {
         supportedLevels: [SettingLevel.PLATFORM],
         displayName: _td("settings|preferences|enable_hardware_acceleration"),
         default: true,
-    },
+    }
 };

src/settings/controllers/MediaPreviewConfigController.ts

@@ -0,0 +1,68 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { ClientEvent, MatrixEvent, MediaPreviewConfig, type MatrixClient } from "matrix-js-sdk/src/matrix";
+
+import { SettingLevel } from "../SettingLevel.ts";
+import MatrixClientBackedController from "./MatrixClientBackedController.ts";
+
+
+const CLIENT_KEY = "m.media_preview_config";
+
+/**
+ * TODO
+ */
+export default class MediaPreviewConfigController extends MatrixClientBackedController {
+    private globalSetting: MediaPreviewConfig = MediaPreviewConfig.Private;
+
+    public constructor() {
+        super();
+    }
+
+    private getRoomValue = (roomId: string): MediaPreviewConfig|null => {
+        return this.client?.getRoom(roomId)?.getAccountData(CLIENT_KEY)?.getContent().value ?? null;
+    }
+
+    private onAccountData = (event: MatrixEvent): void => {
+        // TODO: Validate.
+        const roomId = event.getRoomId();
+        if (!roomId) {
+            this.globalSetting = event.getContent().value;
+        }
+    };
+
+    protected async initMatrixClient(newClient: MatrixClient, oldClient?: MatrixClient): Promise<void> {
+        oldClient?.off(ClientEvent.AccountData, this.onAccountData);
+        newClient.on(ClientEvent.AccountData, this.onAccountData);
+        const accountData = newClient.getAccountData(CLIENT_KEY);
+        if (accountData) this.onAccountData(accountData);
+    }
+
+    public getValueOverride(level: SettingLevel, roomId: string | null,): MediaPreviewConfig {
+        // TODO: Use SettingLevel?
+        if (roomId) {
+            return this.getRoomValue(roomId) ?? this.globalSetting;
+        }
+        return this.globalSetting;
+    }
+
+    public get settingDisabled(): boolean | string {
+        return false;
+    }
+
+    public onChange(_level: SettingLevel, roomId: string | null, newValue: MediaPreviewConfig): void {
+        if (roomId) {
+            this.client?.setRoomAccountData(roomId, "m.media_preview_config", {
+                value: newValue
+            });
+            return;
+        }
+        this.client?.setAccountDataRaw( "m.media_preview_config", {
+            value: newValue
+        });
+    }
+}