Move image processing to worker

app/components/place-photo-item.gjs

@@ -37,29 +37,26 @@ export default class PlacePhotoItem extends Component {
   uploadTask = task(async (file) => {
     this.error = '';
     try {
-      // 1. Process main image
+      // 1. Process main image and generate blurhash in worker
       const mainData = await this.imageProcessor.process(
         file,
         MAX_IMAGE_DIMENSION,
-        IMAGE_QUALITY
+        IMAGE_QUALITY,
+        true // computeBlurhash
       );
 
-      // 2. Generate blurhash from main image data
+      // 2. Process thumbnail (no blurhash needed)
-      const blurhash = await this.imageProcessor.generateBlurhash(
-        mainData.imageData
-      );
-
-      // 3. Process thumbnail
       const thumbData = await this.imageProcessor.process(
         file,
         MAX_THUMBNAIL_DIMENSION,
-        THUMBNAIL_QUALITY
+        THUMBNAIL_QUALITY,
+        false
       );
 
-      // 4. Upload main image (to all servers concurrently)
+      // 3. Upload main image (to all servers concurrently)
       const mainUploadPromise = this.blossom.upload(mainData.blob);
 
-      // 5. Upload thumbnail (to all servers concurrently)
+      // 4. Upload thumbnail (to all servers concurrently)
       const thumbUploadPromise = this.blossom.upload(thumbData.blob);
 
       // Await both uploads
@@ -76,7 +73,7 @@ export default class PlacePhotoItem extends Component {
           url: mainResult.url,
           fallbackUrls: mainResult.fallbackUrls,
           thumbUrl: thumbResult.url,
-          blurhash,
+          blurhash: mainData.blurhash,
           type: 'image/jpeg',
           dim: mainData.dim,
           hash: mainResult.hash,

app/services/image-processor.js

@@ -1,74 +1,82 @@
 import Service from '@ember/service';
-import { encode } from 'blurhash';
+// We use the special Vite query parameter to load this as a web worker
+import Worker from '../workers/image-processor?worker';
 
 export default class ImageProcessorService extends Service {
-  async process(file, maxDimension, quality) {
+  _worker = null;
+  _callbacks = new Map();
+  _msgId = 0;
+
+  constructor() {
+    super(...arguments);
+    this._initWorker();
+  }
+
+  _initWorker() {
+    if (!this._worker && typeof Worker !== 'undefined') {
+      try {
+        this._worker = new Worker();
+        this._worker.onmessage = this._handleMessage.bind(this);
+        this._worker.onerror = this._handleError.bind(this);
+      } catch (e) {
+        console.warn('Failed to initialize image-processor worker:', e);
+      }
+    }
+  }
+
+  _handleMessage(e) {
+    const { id, success, blob, dim, blurhash, error } = e.data;
+    const resolver = this._callbacks.get(id);
+
+    if (resolver) {
+      this._callbacks.delete(id);
+      if (success) {
+        resolver.resolve({ blob, dim, blurhash });
+      } else {
+        resolver.reject(new Error(error));
+      }
+    }
+  }
+
+  _handleError(error) {
+    console.error('Image Processor Worker Error:', error);
+    // Reject all pending jobs
+    for (const [, resolver] of this._callbacks.entries()) {
+      resolver.reject(new Error('Worker crashed'));
+    }
+    this._callbacks.clear();
+    // Restart the worker for future jobs
+    this._worker.terminate();
+    this._worker = null;
+    this._initWorker();
+  }
+
+  async process(file, maxDimension, quality, computeBlurhash = false) {
+    if (!this._worker) {
+      // Fallback if worker initialization failed (e.g. incredibly old browsers)
+      throw new Error('Image processor worker is not available.');
+    }
+
     return new Promise((resolve, reject) => {
-      const url = URL.createObjectURL(file);
+      const id = ++this._msgId;
-      const img = new Image();
+      this._callbacks.set(id, { resolve, reject });
 
-      img.onload = () => {
+      this._worker.postMessage({
-        URL.revokeObjectURL(url);
+        id,
-
+        file,
-        let width = img.width;
+        maxDimension,
-        let height = img.height;
+        quality,
-
+        computeBlurhash,
-        if (width > height) {
+      });
-          if (width > maxDimension) {
-            height = Math.round(height * (maxDimension / width));
-            width = maxDimension;
-          }
-        } else {
-          if (height > maxDimension) {
-            width = Math.round(width * (maxDimension / height));
-            height = maxDimension;
-          }
-        }
-
-        const canvas = document.createElement('canvas');
-        canvas.width = width;
-        canvas.height = height;
-
-        const ctx = canvas.getContext('2d');
-        if (!ctx) {
-          return reject(new Error('Failed to get canvas context'));
-        }
-
-        // Draw image on canvas, this inherently strips EXIF/metadata
-        ctx.drawImage(img, 0, 0, width, height);
-
-        const imageData = ctx.getImageData(0, 0, width, height);
-        const dim = `${width}x${height}`;
-
-        canvas.toBlob(
-          (blob) => {
-            if (blob) {
-              resolve({ blob, dim, imageData });
-            } else {
-              reject(new Error('Canvas toBlob failed'));
-            }
-          },
-          'image/jpeg',
-          quality
-        );
-      };
-
-      img.onerror = () => {
-        URL.revokeObjectURL(url);
-        reject(new Error('Failed to load image for processing'));
-      };
-
-      img.src = url;
     });
   }
 
-  async generateBlurhash(imageData, componentX = 4, componentY = 3) {
+  willDestroy() {
-    return encode(
+    super.willDestroy(...arguments);
-      imageData.data,
+    if (this._worker) {
-      imageData.width,
+      this._worker.terminate();
-      imageData.height,
+      this._worker = null;
-      componentX,
+    }
-      componentY
+    this._callbacks.clear();
-    );
   }
 }

app/styles/app.css

@@ -216,7 +216,7 @@ body {
   padding: 2rem 1.5rem;
   text-align: center;
   transition: all 0.2s ease;
-  margin: 1.5rem 0 1rem 0;
+  margin: 1.5rem 0 1rem;
   background-color: rgb(255 255 255 / 2%);
   cursor: pointer;
 }

app/workers/image-processor.js

@@ -0,0 +1,68 @@
+import { encode } from 'blurhash';
+
+self.onmessage = async (e) => {
+  const { id, file, maxDimension, quality, computeBlurhash } = e.data;
+
+  try {
+    // 1. Decode image off main thread
+    const bitmap = await createImageBitmap(file);
+
+    let width = bitmap.width;
+    let height = bitmap.height;
+
+    // 2. Calculate aspect-ratio preserving dimensions
+    if (width > height) {
+      if (width > maxDimension) {
+        height = Math.round(height * (maxDimension / width));
+        width = maxDimension;
+      }
+    } else {
+      if (height > maxDimension) {
+        width = Math.round(width * (maxDimension / height));
+        height = maxDimension;
+      }
+    }
+
+    // 3. Create OffscreenCanvas and draw
+    const canvas = new OffscreenCanvas(width, height);
+    const ctx = canvas.getContext('2d');
+
+    if (!ctx) {
+      throw new Error('Failed to get 2d context from OffscreenCanvas');
+    }
+
+    ctx.drawImage(bitmap, 0, 0, width, height);
+
+    // 4. Generate Blurhash (if requested)
+    let blurhash = null;
+    if (computeBlurhash) {
+      const imageData = ctx.getImageData(0, 0, width, height);
+      blurhash = encode(imageData.data, width, height, 4, 3);
+    }
+
+    // 5. Compress to JPEG Blob
+    const blob = await canvas.convertToBlob({
+      type: 'image/jpeg',
+      quality: quality,
+    });
+
+    const dim = `${width}x${height}`;
+
+    // 6. Send results back to main thread
+    self.postMessage({
+      id,
+      success: true,
+      blob,
+      dim,
+      blurhash,
+    });
+
+    bitmap.close();
+  } catch (error) {
+    self.postMessage({
+      id,
+      success: false,
+      error: error.message,
+    });
+  }
+};