fix(media): "Compress image" no longer blackens transparent images or freezes animations (#331)

Compression re-encodes through a canvas to JPEG. Only PNG was skipped,
so a transparent WebP came out on a black background, and an animated
GIF or WebP became one still frame. GIF and APNG are no longer offered;
an animated WebP (VP8X animation flag) or any image with a transparent
pixel is kept as the original.

Fixes #331

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/plugins/call/CallEmbed.ts

@@ -218,9 +218,6 @@ export class CallEmbed {
       //  - transparent background so the room wallpaper shows through natively
       lotusCallState: 'true',
       lotusTransparent: 'true',
-      // [Gitea #293] the fork applies the theme with transparency anyway, and
-      // warned in every call that lotusTheme wasn't set
-      lotusTheme: 'true',
       // [Gitea #43] The fork hides its own footer (we draw the call bar) and
       // sets its root color-scheme from the theme, instead of us injecting CSS.
       lotusHostControls: 'true',

src/app/utils/imageCompression.test.ts

@@ -1,6 +1,11 @@
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { formatFileSize, isCompressible } from './imageCompression';
+import {
+  formatFileSize,
+  hasTransparency,
+  isAnimatedWebp,
+  isCompressible,
+} from './imageCompression';
 
 test('formatFileSize formats bytes below 1KB as B', () => {
   assert.equal(formatFileSize(0), '0 B');
@@ -25,14 +30,38 @@ test('formatFileSize formats values in the MB range', () => {
 test('isCompressible accepts raster image types', () => {
   assert.equal(isCompressible({ type: 'image/png' } as Blob), true);
   assert.equal(isCompressible({ type: 'image/jpeg' } as Blob), true);
-  assert.equal(isCompressible({ type: 'image/gif' } as Blob), true);
   assert.equal(isCompressible({ type: 'image/webp' } as Blob), true);
 });
 
 test('isCompressible rejects svg, empty type, and non-images', () => {
   assert.equal(isCompressible({ type: 'image/svg+xml' } as Blob), false);
+  // [Gitea #331] usually animated; a canvas keeps one frame
+  assert.equal(isCompressible({ type: 'image/gif' } as Blob), false);
+  assert.equal(isCompressible({ type: 'image/apng' } as Blob), false);
   assert.equal(isCompressible({ type: '' } as Blob), false);
   assert.equal(isCompressible({ type: 'application/pdf' } as Blob), false);
   assert.equal(isCompressible({ type: 'text/plain' } as Blob), false);
   assert.equal(isCompressible({ type: 'video/mp4' } as Blob), false);
 });
+
+const webpHeader = (chunk: string, flags = 0) => {
+  const b = new Uint8Array(32);
+  const put = (at: number, str: string) => b.set(new TextEncoder().encode(str), at);
+  put(0, 'RIFF');
+  put(8, 'WEBP');
+  put(12, chunk);
+  b[20] = flags;
+  return b;
+};
+
+test('isAnimatedWebp: VP8X with the animation flag (#331)', () => {
+  assert.equal(isAnimatedWebp(webpHeader('VP8X', 0x02)), true);
+  assert.equal(isAnimatedWebp(webpHeader('VP8X', 0x10)), false, 'alpha flag only');
+  assert.equal(isAnimatedWebp(webpHeader('VP8 ')), false, 'simple lossy');
+  assert.equal(isAnimatedWebp(new Uint8Array(8)), false);
+});
+
+test('hasTransparency (#331)', () => {
+  assert.equal(hasTransparency(new Uint8ClampedArray([1, 2, 3, 255, 4, 5, 6, 255])), false);
+  assert.equal(hasTransparency(new Uint8ClampedArray([1, 2, 3, 255, 0, 0, 0, 0])), true);
+});

src/app/utils/imageCompression.ts

@@ -8,11 +8,32 @@ export type CompressionResult = {
   height: number;
 };
 
-// Any raster image the browser can render to canvas can be compressed to JPEG.
-// SVG is vector and must stay as-is; GIF animation is lost on canvas but static
-// frames compress fine. Empty type string (undetected MIME) is excluded.
+// Raster images the browser can render to canvas can be compressed to JPEG.
+// SVG is vector and must stay as-is. [Gitea #331] GIF and APNG are usually
+// animated, and a canvas keeps only the first frame, so they aren't offered.
+// Empty type string (undetected MIME) is excluded.
+const NOT_COMPRESSIBLE = new Set(['image/svg+xml', 'image/gif', 'image/apng']);
 const isCompressibleType = (type: string): boolean =>
-  type.startsWith('image/') && type !== 'image/svg+xml' && type !== '';
+  type.startsWith('image/') && !NOT_COMPRESSIBLE.has(type);
+
+/**
+ * Pure: whether a WebP file is animated. An animated WebP is a VP8X file
+ * whose header has the animation flag (byte 20, bit 0x02) and an ANIM chunk.
+ */
+export function isAnimatedWebp(bytes: Uint8Array): boolean {
+  const ascii = (at: number, len: number) => String.fromCharCode(...bytes.subarray(at, at + len));
+  if (bytes.length < 21 || ascii(0, 4) !== 'RIFF' || ascii(8, 4) !== 'WEBP') return false;
+  // Bit 0x02 of the VP8X flags byte (no-bitwise: test it arithmetically).
+  return ascii(12, 4) === 'VP8X' && Math.floor(bytes[20] / 2) % 2 === 1;
+}
+
+/** Pure: whether RGBA pixel data has any pixel that isn't fully opaque. */
+export function hasTransparency(rgba: Uint8ClampedArray): boolean {
+  for (let i = 3; i < rgba.length; i += 4) {
+    if (rgba[i] !== 255) return true;
+  }
+  return false;
+}
 
 /** Returns true if this file can be compressed via canvas (any raster image type). */
 export function isCompressible(file: File | Blob): boolean {
@@ -28,7 +49,8 @@ const JPEG_OUTPUT_TYPE = 'image/jpeg';
  *
  * PNG is skipped entirely: it may carry an alpha channel, and re-encoding to
  * JPEG composites transparency onto an opaque (black) background, corrupting the
- * image. Returning null makes callers fall back to uploading the lossless
+ * image. Any other image with transparent pixels, and animated WebP, are left
+ * alone for the same reason (#331). Returning null makes callers fall back to uploading the lossless
  * original. The image is decoded with `imageOrientation: 'from-image'` so any
  * EXIF orientation is baked into the pixels instead of being silently dropped.
  */
@@ -39,6 +61,15 @@ export async function compressImage(
   if (!isCompressibleType(file.type)) return null;
   // Skip PNG (potential alpha) — re-encoding to JPEG would flatten transparency.
   if (file.type === 'image/png') return null;
+  // [Gitea #331] An animated WebP would become a single still frame.
+  if (file.type === 'image/webp') {
+    try {
+      const head = new Uint8Array(await file.slice(0, 32).arrayBuffer());
+      if (isAnimatedWebp(head)) return null;
+    } catch {
+      return null;
+    }
+  }
 
   let bitmap: ImageBitmap;
   try {
@@ -60,6 +91,13 @@ export async function compressImage(
   }
   ctx.drawImage(bitmap, 0, 0);
   bitmap.close();
+  // [Gitea #331] JPEG has no alpha: a transparent WebP (sticker, logo) came out
+  // with a black background. Keep any image with transparency as the original.
+  try {
+    if (hasTransparency(ctx.getImageData(0, 0, width, height).data)) return null;
+  } catch {
+    return null;
+  }
 
   return new Promise((resolve) => {
     canvas.toBlob(

vite.config.js

@@ -87,106 +87,97 @@ function copyPdfWorker() {
   };
 }
 
-// The denoise assets the fork loads from ./denoise/ at runtime, as
-// [source, path under denoise/] pairs; `dir: true` entries are whole trees.
-// Shared by the build copy and the dev server (Gitea #293).
-function denoiseSources() {
-  const sapphi = path.resolve('node_modules/@sapphi-red/web-noise-suppressor/dist');
-  const dfnVendor = path.resolve('build/denoise-vendor/deepfilternet');
-  return {
-    // All bundled denoise assets are REQUIRED: every entry backs a model the
-    // UI can select (RNNoise, Speex) or the optional noise gate.
-    sapphi: [
-      [path.join(sapphi, 'rnnoise/workletProcessor.js'), 'rnnoiseWorklet.js'],
-      [path.join(sapphi, 'rnnoise.wasm'), 'rnnoise.wasm'],
-      [path.join(sapphi, 'rnnoise_simd.wasm'), 'rnnoise_simd.wasm'],
-      [path.join(sapphi, 'speex/workletProcessor.js'), 'speexWorklet.js'],
-      [path.join(sapphi, 'speex.wasm'), 'speex.wasm'],
-      [path.join(sapphi, 'noiseGate/workletProcessor.js'), 'noiseGateWorklet.js'],
-    ],
-    // DTLN (@workadventure/noise-suppression): a self-contained ES module that
-    // resolves its own worklet, LiteRT WASM runtime and TFLite models via
-    // `import.meta.url`, so its whole dist/ tree is served intact.
-    dtln: [path.resolve('node_modules/@workadventure/noise-suppression/dist'), 'workadventure'],
-    // DeepFilterNet 3: the ESM (worklet inlined) plus the vendored wasm and ONNX
-    // model (CDN-free / Tauri-CSP safe), in the package's expected v2/ layout.
-    dfn: [
-      [
-        path.resolve('node_modules/deepfilternet3-noise-filter/dist/index.esm.js'),
-        'deepfilternet/index.esm.js',
-      ],
-      [path.join(dfnVendor, 'v2/pkg/df_bg.wasm'), 'deepfilternet/v2/pkg/df_bg.wasm'],
-      [
-        path.join(dfnVendor, 'v2/models/DeepFilterNet3_onnx.tar.gz'),
-        'deepfilternet/v2/models/DeepFilterNet3_onnx.tar.gz',
-      ],
-    ],
-  };
-}
-
-// Lotus ML noise suppression: ship the denoise worklets/wasm/models alongside
-// the vendored Element Call bundle. Runs after viteStaticCopy has populated
-// dist/public/element-call (closeBundle order). [Gitea #293] The dev server
-// serves the same files at the same URLs, so `npm start` can test denoise.
+// Lotus ML noise suppression: ship the RNNoise worklet/wasm + our getUserMedia
+// shim alongside the vendored Element Call bundle, and inject the shim <script>
+// into EC's index.html so it runs before EC captures the mic. Runs after
+// viteStaticCopy has populated dist/public/element-call (closeBundle order).
 function lotusDenoise() {
-  const DEV_PREFIX = '/public/element-call/denoise/';
   return {
     name: 'lotus-denoise',
-    configureServer(server) {
-      const { sapphi, dtln, dfn } = denoiseSources();
-      const files = new Map([...sapphi, ...dfn].map(([src, rel]) => [rel, src]));
-      const types = { '.js': 'text/javascript', '.wasm': 'application/wasm' };
-      server.middlewares.use((req, res, next) => {
-        const url = (req.url ?? '').split('?')[0];
-        if (!url.startsWith(DEV_PREFIX)) return next();
-        const rel = decodeURIComponent(url.slice(DEV_PREFIX.length));
-        let file = files.get(rel);
-        if (!file && rel.startsWith(`${dtln[1]}/`)) {
-          const candidate = path.resolve(dtln[0], rel.slice(dtln[1].length + 1));
-          if (candidate.startsWith(dtln[0] + path.sep)) file = candidate;
-        }
-        if (!file || !fs.existsSync(file)) return next();
-        res.setHeader('Content-Type', types[path.extname(file)] ?? 'application/octet-stream');
-        fs.createReadStream(file).pipe(res);
-        return undefined;
-      });
-    },
     closeBundle() {
       const ecDir = path.resolve('dist/public/element-call');
       if (!fs.existsSync(ecDir)) return;
 
       const denoiseDir = path.join(ecDir, 'denoise');
       fs.mkdirSync(denoiseDir, { recursive: true });
-      const { sapphi, dtln, dfn } = denoiseSources();
 
-      // A missing source means a partial/changed install would otherwise
-      // silently ship a broken ML feature (worklet 404 -> raw mic), so we fail
-      // the build instead.
-      const missing = sapphi.filter(([s]) => !fs.existsSync(s)).map(([s]) => s);
+      const sapphi = path.resolve('node_modules/@sapphi-red/web-noise-suppressor/dist');
+      // All bundled denoise assets are REQUIRED: every entry backs a model the
+      // UI can select (RNNoise, Speex) or the optional noise gate. A missing
+      // source means a partial/changed install would otherwise silently ship a
+      // broken ML feature (worklet 404 -> raw mic), so we fail the build instead.
+      const assets = [
+        [
+          path.join(sapphi, 'rnnoise/workletProcessor.js'),
+          path.join(denoiseDir, 'rnnoiseWorklet.js'),
+        ],
+        [path.join(sapphi, 'rnnoise.wasm'), path.join(denoiseDir, 'rnnoise.wasm')],
+        [path.join(sapphi, 'rnnoise_simd.wasm'), path.join(denoiseDir, 'rnnoise_simd.wasm')],
+        [path.join(sapphi, 'speex/workletProcessor.js'), path.join(denoiseDir, 'speexWorklet.js')],
+        [path.join(sapphi, 'speex.wasm'), path.join(denoiseDir, 'speex.wasm')],
+        [
+          path.join(sapphi, 'noiseGate/workletProcessor.js'),
+          path.join(denoiseDir, 'noiseGateWorklet.js'),
+        ],
+      ];
+      const missing = assets.filter(([s]) => !fs.existsSync(s)).map(([s]) => s);
       if (missing.length > 0) {
         throw new Error(
           `[lotus-denoise] Required denoise asset(s) missing — build aborted to avoid shipping a broken ML feature:\n  ${missing.join('\n  ')}`,
         );
       }
-      sapphi.forEach(([s, rel]) => fs.copyFileSync(s, path.join(denoiseDir, rel)));
+      assets.forEach(([s, d]) => fs.copyFileSync(s, d));
 
-      const dtlnEntry = path.join(dtln[0], 'audio-worklet.js');
+      // DTLN (@workadventure/noise-suppression): unlike the flat sapphi
+      // worklets, this package is a self-contained ES module that resolves its
+      // own AudioWorklet processor, LiteRT WASM runtime and TFLite models via
+      // `import.meta.url`. So we copy its whole dist/ tree intact to
+      // denoise/workadventure/ (preserving assets/ + vendor/) and let the shim
+      // dynamic-import denoise/workadventure/audio-worklet.js at runtime. The
+      // entry module is required — fail the build if the install is broken.
+      const dtlnSrc = path.resolve('node_modules/@workadventure/noise-suppression/dist');
+      const dtlnEntry = path.join(dtlnSrc, 'audio-worklet.js');
       if (!fs.existsSync(dtlnEntry)) {
         throw new Error(
           `[lotus-denoise] DTLN entry missing (${dtlnEntry}) — build aborted. ` +
             'Run `npm ci` to install @workadventure/noise-suppression.',
         );
       }
-      fs.cpSync(dtln[0], path.join(denoiseDir, dtln[1]), { recursive: true });
+      fs.cpSync(dtlnSrc, path.join(denoiseDir, 'workadventure'), { recursive: true });
 
-      const dfnMissing = dfn.filter(([s]) => !fs.existsSync(s)).map(([s]) => s);
+      // DeepFilterNet 3 (deepfilternet3-noise-filter): the npm package ships only
+      // its ESM (index.esm.js) with the AudioWorklet processor + wasm-bindgen glue
+      // INLINED as a string (loaded via a Blob URL, no CDN for the worklet). The
+      // only runtime CDN fetches are its single-threaded `df_bg.wasm` and the
+      // ONNX `DeepFilterNet3_onnx.tar.gz` model — which we VENDOR locally (under
+      // build/denoise-vendor/deepfilternet/) and serve, overriding the package's
+      // cdnUrl to our self-hosted base. This keeps the feature CDN-free / Tauri-CSP
+      // safe. We copy the ESM (the shim dynamic-imports it, mirroring DTLN) plus
+      // the vendored assets, preserving the package's expected v2/... layout. All
+      // are required — a missing entry means a broken install, so fail the build.
+      const dfnEsm = path.resolve('node_modules/deepfilternet3-noise-filter/dist/index.esm.js');
+      const dfnVendor = path.resolve('build/denoise-vendor/deepfilternet');
+      const dfnAssets = [
+        [dfnEsm, path.join(denoiseDir, 'deepfilternet/index.esm.js')],
+        [
+          path.join(dfnVendor, 'v2/pkg/df_bg.wasm'),
+          path.join(denoiseDir, 'deepfilternet/v2/pkg/df_bg.wasm'),
+        ],
+        [
+          path.join(dfnVendor, 'v2/models/DeepFilterNet3_onnx.tar.gz'),
+          path.join(denoiseDir, 'deepfilternet/v2/models/DeepFilterNet3_onnx.tar.gz'),
+        ],
+      ];
+      const dfnMissing = dfnAssets.filter(([s]) => !fs.existsSync(s)).map(([s]) => s);
       if (dfnMissing.length > 0) {
         throw new Error(
-          `[lotus-denoise] DeepFilterNet 3 asset(s) missing — build aborted to avoid shipping a broken ML feature:\n  ${dfnMissing.join('\n  ')}\n(Run \`npm ci\`; the vendored wasm/model live under build/denoise-vendor/deepfilternet/.)`,
+          '[lotus-denoise] DeepFilterNet 3 asset(s) missing — build aborted to avoid ' +
+            'shipping a broken ML feature:\n  ' +
+            dfnMissing.join('\n  ') +
+            '\n(Run `npm ci`; the vendored wasm/model live under build/denoise-vendor/deepfilternet/.)',
         );
       }
-      dfn.forEach(([s, rel]) => {
-        const d = path.join(denoiseDir, rel);
+      dfnAssets.forEach(([s, d]) => {
         fs.mkdirSync(path.dirname(d), { recursive: true });
         fs.copyFileSync(s, d);
       });