Squash Odysseus development history

static/js/editor/thumbnail-worker.js

@@ -0,0 +1,18 @@
+/* Encode a completed document surface without blocking the editor thread. */
+self.onmessage = async event => {
+  const { bitmap, maxDim = 160, quality = 0.6 } = event.data || {};
+  try {
+    if (!bitmap?.width || !bitmap?.height) throw new Error('Thumbnail source is empty');
+    const scale = Math.min(1, maxDim / Math.max(bitmap.width, bitmap.height));
+    const width = Math.max(1, Math.round(bitmap.width * scale));
+    const height = Math.max(1, Math.round(bitmap.height * scale));
+    const canvas = new OffscreenCanvas(width, height);
+    canvas.getContext('2d').drawImage(bitmap, 0, 0, width, height);
+    const blob = await canvas.convertToBlob({ type: 'image/jpeg', quality });
+    self.postMessage({ blob });
+  } catch (error) {
+    self.postMessage({ error: String(error?.message || error) });
+  } finally {
+    bitmap?.close?.();
+  }
+};