wip

# Conflicts:
#	codecs/cpp.Dockerfile
#	codecs/imagequant/example.html
#	codecs/webp/dec/webp_dec.d.ts
#	codecs/webp/dec/webp_dec.js
#	codecs/webp/dec/webp_dec.wasm
#	codecs/webp/enc/webp_enc.d.ts
#	codecs/webp/enc/webp_enc.js
#	codecs/webp/enc/webp_enc.wasm
#	package-lock.json
#	package.json
#	src/codecs/tiny.webp
#	src_old/codecs/encoders.ts
#	src_old/codecs/processor-worker/tiny.avif
#	src_old/codecs/processor-worker/tiny.webp
#	src_old/codecs/tiny.webp
#	src_old/components/compress/index.tsx
#	src_old/lib/util.ts
#	src_old/sw/util.ts

src_old/codecs/rotate/processor.ts

@@ -0,0 +1,43 @@
+import wasmUrl from '../../../codecs/rotate/rotate.wasm';
+import { RotateOptions, RotateModuleInstance } from './processor-meta';
+
+// We are loading a 500B module here. Loading the code to feature-detect
+// `instantiateStreaming` probably takes longer to load than the time we save by
+// using `instantiateStreaming` in the first place. So let’s just use
+// `ArrayBuffer`s here.
+const instancePromise = fetch(wasmUrl)
+  .then((r) => r.arrayBuffer())
+  .then((buf) => WebAssembly.instantiate(buf));
+
+export async function rotate(
+  data: ImageData,
+  opts: RotateOptions,
+): Promise<ImageData> {
+  const { instance } = (await instancePromise) as {
+    instance: RotateModuleInstance;
+  };
+
+  // Number of wasm memory pages (á 64KiB) needed to store the image twice.
+  const bytesPerImage = data.width * data.height * 4;
+  const numPagesNeeded = Math.ceil((bytesPerImage * 2 + 8) / (64 * 1024));
+  // Only count full pages, just to be safe.
+  const numPagesAvailable = Math.floor(
+    instance.exports.memory.buffer.byteLength / (64 * 1024),
+  );
+  const additionalPagesToAllocate = numPagesNeeded - numPagesAvailable;
+
+  if (additionalPagesToAllocate > 0) {
+    instance.exports.memory.grow(additionalPagesToAllocate);
+  }
+  const view = new Uint8ClampedArray(instance.exports.memory.buffer);
+  view.set(data.data, 8);
+
+  instance.exports.rotate(data.width, data.height, opts.rotate);
+
+  const flipDimensions = opts.rotate % 180 !== 0;
+  return new ImageData(
+    view.slice(bytesPerImage + 8, bytesPerImage * 2 + 8),
+    flipDimensions ? data.height : data.width,
+    flipDimensions ? data.width : data.height,
+  );
+}