Update visual style and sandbox properly

res/css/views/messages/_MessageActionBar.scss

@@ -107,3 +107,12 @@ limitations under the License.
 .mx_MessageActionBar_cancelButton::after {
     mask-image: url('$(res)/img/element-icons/trashcan.svg');
 }
+
+.mx_MessageActionBar_downloadButton::after {
+    mask-size: 16px;
+    mask-image: url('$(res)/img/download.svg');
+}
+
+.mx_MessageActionBar_downloadButton.mx_MessageActionBar_downloadSpinnerButton::after {
+    background-color: transparent; // hide the download icon mask
+}

src/components/views/messages/DownloadActionButton.tsx

@@ -0,0 +1,110 @@
+/*
+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 { MatrixEvent } from "matrix-js-sdk/src";
+import { MediaEventHelper } from "../../../utils/MediaEventHelper";
+import React, { createRef } from "react";
+import { RovingAccessibleTooltipButton } from "../../../accessibility/RovingTabIndex";
+import Spinner from "../elements/Spinner";
+import classNames from "classnames";
+import { _t } from "../../../languageHandler";
+import { replaceableComponent } from "../../../utils/replaceableComponent";
+import { DOWNLOAD_ICON_URL } from "./MFileBody";
+
+interface IProps {
+    mxEvent: MatrixEvent;
+
+    // XXX: It can take a cycle or two for the MessageActionBar to have all the props/setup
+    // required to get us a MediaEventHelper, so we use a getter function instead to prod for
+    // one.
+    mediaEventHelperGet: () => MediaEventHelper;
+}
+
+interface IState {
+    loading: boolean;
+    blob?: Blob;
+}
+
+@replaceableComponent("views.messages.DownloadActionButton")
+export class DownloadActionButton extends React.PureComponent<IProps, IState> {
+    private iframe: React.RefObject<HTMLIFrameElement> = createRef();
+
+    public constructor(props: IProps) {
+        super(props);
+
+        this.state = {
+            loading: false,
+        };
+    }
+
+    private onDownloadClick = async () => {
+        if (this.state.loading) return;
+
+        this.setState({ loading: true });
+
+        if (this.state.blob) {
+            // Cheat and trigger a download, again.
+            return this.onFrameLoad();
+        }
+
+        const blob = await this.props.mediaEventHelperGet().sourceBlob.value;
+        this.setState({ blob });
+    };
+
+    private onFrameLoad = () => {
+        this.setState({ loading: false });
+
+        // we aren't showing the iframe, so we can send over the bare minimum styles and such.
+        this.iframe.current.contentWindow.postMessage({
+            imgSrc: DOWNLOAD_ICON_URL,
+            imgStyle: null,
+            style: "",
+            blob: this.state.blob,
+            download: this.props.mediaEventHelperGet().fileName,
+            textContent: "",
+            auto: true, // autodownload
+        }, '*');
+    };
+
+    public render() {
+        let spinner: JSX.Element;
+        if (this.state.loading) {
+            spinner = <Spinner w={18} h={18} />;
+        }
+
+        const classes = classNames({
+            'mx_MessageActionBar_maskButton': true,
+            'mx_MessageActionBar_downloadButton': true,
+            'mx_MessageActionBar_downloadSpinnerButton': !!spinner,
+        });
+
+        return <RovingAccessibleTooltipButton
+            className={classes}
+            title={_t("Download")}
+            onClick={this.onDownloadClick}
+            disabled={!!spinner}
+        >
+            { spinner }
+            { this.state.blob && <iframe
+                src={"usercontent/" /* XXX: Like MFileBody, this should come from the skin */}
+                ref={this.iframe}
+                onLoad={this.onFrameLoad}
+                sandbox="allow-scripts allow-downloads allow-downloads-without-user-activation"
+                style={{ display: "none" }}
+            /> }
+        </RovingAccessibleTooltipButton>;
+    }
+}

src/components/views/messages/MFileBody.tsx

@@ -27,12 +27,12 @@ import { IContent } from "matrix-js-sdk/src";
 import { IMediaEventContent } from "../../../customisations/models/IMediaEventContent";
 import { IBodyProps } from "./IBodyProps";
 
-let downloadIconUrl; // cached copy of the download.svg asset for the sandboxed iframe later on
+export let DOWNLOAD_ICON_URL; // cached copy of the download.svg asset for the sandboxed iframe later on
 
 async function cacheDownloadIcon() {
-    if (downloadIconUrl) return; // cached already
+    if (DOWNLOAD_ICON_URL) return; // cached already
     const svg = await fetch(require("../../../../res/img/download.svg")).then(r => r.text());
-    downloadIconUrl = "data:image/svg+xml;base64," + window.btoa(svg);
+    DOWNLOAD_ICON_URL = "data:image/svg+xml;base64," + window.btoa(svg);
 }
 
 // Cache the asset immediately
@@ -74,7 +74,7 @@ cacheDownloadIcon();
  * @param {HTMLElement} element The element to get the current style of.
  * @return {string} The CSS style encoded as a string.
  */
-function computedStyle(element) {
+export function computedStyle(element: HTMLElement) {
     if (!element) {
         return "";
     }
@@ -217,7 +217,7 @@ export default class MFileBody extends React.Component<IProps, IState> {
             // When the iframe loads we tell it to render a download link
             const onIframeLoad = (ev) => {
                 ev.target.contentWindow.postMessage({
-                    imgSrc: downloadIconUrl,
+                    imgSrc: DOWNLOAD_ICON_URL,
                     imgStyle: null, // it handles this internally for us. Useful if a downstream changes the icon.
                     style: computedStyle(this.dummyLink.current),
                     blob: this.state.decryptedBlob,

src/components/views/messages/MessageActionBar.js

@@ -33,6 +33,7 @@ import { canCancel } from "../context_menus/MessageContextMenu";
 import Resend from "../../../Resend";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
 import { MediaEventHelper } from "../../../utils/MediaEventHelper";
+import { DownloadActionButton } from "./DownloadActionButton";
 
 const OptionsButton = ({ mxEvent, getTile, getReplyThread, permalinkCreator, onFocusChange }) => {
     const [menuDisplayed, button, openMenu, closeMenu] = useContextMenu();
@@ -176,21 +177,6 @@ export default class MessageActionBar extends React.PureComponent {
         });
     };
 
-    onDownloadClick = async (ev) => {
-        if (!this.props.getTile || !this.props.getTile().getMediaHelper) {
-            console.warn("Action bar triggered a download but the event tile is missing a media helper");
-            return;
-        }
-
-        // TODO: Maybe just call into MFileBody and render it as null
-        const src = this.props.getTile().getMediaHelper();
-        const a = document.createElement("a");
-        a.href = await src.sourceUrl.value;
-        a.download = "todo.png";
-        a.target = "_blank";
-        a.click();
-    };
-
     /**
      * Runs a given fn on the set of possible events to test. The first event
      * that passes the checkFn will have fn executed on it. Both functions take
@@ -286,11 +272,9 @@ export default class MessageActionBar extends React.PureComponent {
 
                 // XXX: Assuming that the underlying tile will be a media event if it is eligible media.
                 if (MediaEventHelper.isEligible(this.props.mxEvent)) {
-                    toolbarOpts.splice(0, 0, <RovingAccessibleTooltipButton
-                        className="mx_MessageActionBar_maskButton mx_MessageActionBar_downloadButton"
-                        title={_t("Download")}
-                        onClick={this.onDownloadClick}
-                        disabled={false}
+                    toolbarOpts.splice(0, 0, <DownloadActionButton
+                        mxEvent={this.props.mxEvent}
+                        mediaEventHelperGet={() => this.props.getTile?.().getMediaHelper?.()}
                         key="download"
                     />);
                 }

src/i18n/strings/en_EN.json

@@ -1870,6 +1870,7 @@
     "Saturday": "Saturday",
     "Today": "Today",
     "Yesterday": "Yesterday",
+    "Download": "Download",
     "View Source": "View Source",
     "Messages here are end-to-end encrypted. Verify %(displayName)s in their profile - tap on their avatar.": "Messages here are end-to-end encrypted. Verify %(displayName)s in their profile - tap on their avatar.",
     "Messages in this room are end-to-end encrypted. When people join, you can verify them in their profile, just tap on their avatar.": "Messages in this room are end-to-end encrypted. When people join, you can verify them in their profile, just tap on their avatar.",
@@ -2002,7 +2003,6 @@
     "Zoom in": "Zoom in",
     "Rotate Left": "Rotate Left",
     "Rotate Right": "Rotate Right",
-    "Download": "Download",
     "Information": "Information",
     "Language Dropdown": "Language Dropdown",
     "%(nameList)s %(transitionList)s": "%(nameList)s %(transitionList)s",

src/usercontent/index.js

@@ -1,6 +1,13 @@
+let hasCalled = false;
 function remoteRender(event) {
     const data = event.data;
 
+    // If we're handling secondary calls, start from scratch
+    if (hasCalled) {
+        document.body.replaceWith(document.createElement("BODY"));
+    }
+    hasCalled = true;
+
     const img = document.createElement("span"); // we'll mask it as an image
     img.id = "img";
 

src/utils/MediaEventHelper.ts

@@ -40,6 +40,10 @@ export class MediaEventHelper implements IDestroyable {
         this.media = mediaFromContent(this.event.getContent());
     }
 
+    public get fileName(): string {
+        return this.event.getContent<IMediaEventContent>().body || "download";
+    }
+
     public destroy() {
         if (this.media.isEncrypted) {
             if (this.sourceUrl.present) URL.revokeObjectURL(this.sourceUrl.cachedValue);