Add support for blurhash (MSC2448)

MSC: https://github.com/matrix-org/matrix-doc/pull/2448

While the image loads, we can show a blurred version of it (calculated at upload time) so we don't have a blank space in the timeline.

package.json

@@ -56,6 +56,7 @@
     "@babel/runtime": "^7.10.5",
     "await-lock": "^2.0.1",
     "blueimp-canvas-to-blob": "^3.27.0",
+    "blurhash": "^1.1.3",
     "browser-encrypt-attachment": "^0.3.0",
     "browser-request": "^0.3.3",
     "classnames": "^2.2.6",

src/ContentMessages.tsx

@@ -334,6 +334,7 @@ function uploadFile(matrixClient: MatrixClient, roomId: string, file: File | Blo
             if (file.type) {
                 encryptInfo.mimetype = file.type;
             }
+            // TODO: Blurhash for encrypted media?
             return {"file": encryptInfo};
         });
         (prom as IAbortablePromise<any>).abort = () => {
@@ -344,11 +345,15 @@ function uploadFile(matrixClient: MatrixClient, roomId: string, file: File | Blo
     } else {
         const basePromise = matrixClient.uploadContent(file, {
             progressHandler: progressHandler,
+            onlyContentUri: false,
         });
-        const promise1 = basePromise.then(function(url) {
+        const promise1 = basePromise.then(function(body) {
             if (canceled) throw new UploadCanceledError();
             // If the attachment isn't encrypted then include the URL directly.
-            return {"url": url};
+            return {
+                "url": body.content_uri,
+                "blurhash": body["xyz.amorgan.blurhash"], // TODO: Use `body.blurhash` when MSC2448 lands
+            };
         });
         promise1.abort = () => {
             canceled = true;
@@ -550,6 +555,7 @@ export default class ContentMessages {
             return upload.promise.then(function(result) {
                 content.file = result.file;
                 content.url = result.url;
+                content.info['xyz.amorgan.blurhash'] = result.blurhash; // TODO: Use `blurhash` when MSC2448 lands
             });
         }).then(() => {
             // Await previous message being sent into the room

src/components/views/elements/BlurhashPlaceholder.tsx

@@ -0,0 +1,56 @@
+/*
+ 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 React from 'react';
+import {decode} from "blurhash";
+
+interface IProps {
+    blurhash: string;
+    width: number;
+    height: number;
+}
+
+export default class BlurhashPlaceholder extends React.PureComponent<IProps> {
+    private canvas: React.RefObject<HTMLCanvasElement> = React.createRef();
+
+    public componentDidMount() {
+        this.draw();
+    }
+
+    public componentDidUpdate() {
+        this.draw();
+    }
+
+    private draw() {
+        if (!this.canvas.current) return;
+
+        try {
+            const {width, height} = this.props;
+
+            const pixels = decode(this.props.blurhash, Math.ceil(width), Math.ceil(height));
+            const ctx = this.canvas.current.getContext("2d");
+            const imgData = ctx.createImageData(width, height);
+            imgData.data.set(pixels);
+            ctx.putImageData(imgData, 0, 0);
+        } catch (e) {
+            console.error("Error rendering blurhash: ", e);
+        }
+    }
+
+    public render() {
+        return <canvas height={this.props.height} width={this.props.width} ref={this.canvas} />;
+    }
+}

src/components/views/messages/MImageBody.js

@@ -27,6 +27,7 @@ import { _t } from '../../../languageHandler';
 import SettingsStore from "../../../settings/SettingsStore";
 import MatrixClientContext from "../../../contexts/MatrixClientContext";
 import InlineSpinner from '../elements/InlineSpinner';
+import BlurhashPlaceholder from "../elements/BlurhashPlaceholder";
 
 export default class MImageBody extends React.Component {
     static propTypes = {
@@ -53,6 +54,8 @@ export default class MImageBody extends React.Component {
         this.onClick = this.onClick.bind(this);
         this._isGif = this._isGif.bind(this);
 
+        const imageInfo = this.props.mxEvent.getContent().info;
+
         this.state = {
             decryptedUrl: null,
             decryptedThumbnailUrl: null,
@@ -63,6 +66,7 @@ export default class MImageBody extends React.Component {
             loadedImageDimensions: null,
             hover: false,
             showImage: SettingsStore.getValue("showImages"),
+            blurhash: imageInfo ? imageInfo['xyz.amorgan.blurhash'] : null, // TODO: Use `blurhash` when MSC2448 lands.
         };
 
         this._image = createRef();
@@ -329,7 +333,8 @@ export default class MImageBody extends React.Component {
             infoWidth = content.info.w;
             infoHeight = content.info.h;
         } else {
-            // Whilst the image loads, display nothing.
+            // Whilst the image loads, display nothing. We also don't display a blurhash image
+            // because we don't really know what size of image we'll end up with.
             //
             // Once loaded, use the loaded image dimensions stored in `loadedImageDimensions`.
             //
@@ -368,8 +373,7 @@ export default class MImageBody extends React.Component {
         if (content.file !== undefined && this.state.decryptedUrl === null) {
             placeholder = <InlineSpinner w={32} h={32} />;
         } else if (!this.state.imgLoaded) {
-            // Deliberately, getSpinner is left unimplemented here, MStickerBody overides
-            placeholder = this.getPlaceholder();
+            placeholder = this.getPlaceholder(maxWidth, maxHeight);
         }
 
         let showPlaceholder = Boolean(placeholder);
@@ -391,7 +395,7 @@ export default class MImageBody extends React.Component {
 
         if (!this.state.showImage) {
             img = <HiddenImagePlaceholder style={{ maxWidth: maxWidth + "px" }} />;
-            showPlaceholder = false; // because we're hiding the image, so don't show the sticker icon.
+            showPlaceholder = false; // because we're hiding the image, so don't show the placeholder.
         }
 
         if (this._isGif() && !SettingsStore.getValue("autoplayGifsAndVideos") && !this.state.hover) {
@@ -433,9 +437,9 @@ export default class MImageBody extends React.Component {
     }
 
     // Overidden by MStickerBody
-    getPlaceholder() {
-        // MImageBody doesn't show a placeholder whilst the image loads, (but it could do)
-        return null;
+    getPlaceholder(width, height) {
+        if (!this.state.blurhash) return null;
+        return <BlurhashPlaceholder blurhash={this.state.blurhash} width={width} height={height} />;
     }
 
     // Overidden by MStickerBody

yarn.lock

@@ -2493,6 +2493,11 @@ blueimp-canvas-to-blob@^3.27.0:
   resolved "https://registry.yarnpkg.com/blueimp-canvas-to-blob/-/blueimp-canvas-to-blob-3.27.0.tgz#a2bd5c43587b95dedf0f6998603452d1bfcc9b9e"
   integrity sha512-AcIj+hCw6WquxzJuzC6KzgYmqxLFeTWe88KuY2BEIsW1zbEOfoinDAGlhyvFNGt+U3JElkVSK7anA1FaSdmmfA==
 
+blurhash@^1.1.3:
+  version "1.1.3"
+  resolved "https://registry.yarnpkg.com/blurhash/-/blurhash-1.1.3.tgz#dc325af7da836d07a0861d830bdd63694382483e"
+  integrity sha512-yUhPJvXexbqbyijCIE/T2NCXcj9iNPhWmOKbPTuR/cm7Q5snXYIfnVnz6m7MWOXxODMz/Cr3UcVkRdHiuDVRDw==
+
 bn.js@^4.0.0, bn.js@^4.1.0, bn.js@^4.4.0:
   version "4.11.9"
   resolved "https://registry.yarnpkg.com/bn.js/-/bn.js-4.11.9.tgz#26d556829458f9d1e81fc48952493d0ba3507828"