Better resize methods (#498)

* Port resize to wasm

* Expose resize algorithms

* Lanczos3 working!

* lol copy paste

* Adding support for other resizers

* Don’t track generated README

* Cache wasm instance

src/codecs/resize/processor-sync.ts

@@ -0,0 +1,35 @@
+import { nativeResize, NativeResizeMethod, drawableToImageData } from '../../lib/util';
+import { BrowserResizeOptions, VectorResizeOptions } from './processor-meta';
+import { getContainOffsets } from './util';
+
+export function browserResize(data: ImageData, opts: BrowserResizeOptions): ImageData {
+  let sx = 0;
+  let sy = 0;
+  let sw = data.width;
+  let sh = data.height;
+
+  if (opts.fitMethod === 'contain') {
+    ({ sx, sy, sw, sh } = getContainOffsets(sw, sh, opts.width, opts.height));
+  }
+
+  return nativeResize(
+    data, sx, sy, sw, sh, opts.width, opts.height,
+    opts.method.slice('browser-'.length) as NativeResizeMethod,
+  );
+}
+
+export function vectorResize(data: HTMLImageElement, opts: VectorResizeOptions): ImageData {
+  let sx = 0;
+  let sy = 0;
+  let sw = data.width;
+  let sh = data.height;
+
+  if (opts.fitMethod === 'contain') {
+    ({ sx, sy, sw, sh } = getContainOffsets(sw, sh, opts.width, opts.height));
+  }
+
+  return drawableToImageData(data, {
+    sx, sy, sw, sh,
+    width: opts.width, height: opts.height,
+  });
+}