feat: register features

generator.js

@@ -29,12 +29,20 @@ function draw(width = window.innerWidth, height = window.innerHeight) {
   ctx.fillRect(0, 0, width, height);
   ctx.save();
 
+  const ellipseWidth = ($objkt.seed % 4) + 3;
+  const ellipseHeight = ($objkt.seed % 6) + 3;
+
+  $objkt.registerFeatures({
+    background: colorFeatures(colors.bgFill),
+    object: colorFeatures(colors.ellipseFill),
+  });
+
   ctx.ellipse(
     width / 2,
     height / 2,
-    width / (($objkt.seed % 4) + 3),
-    width / (($objkt.seed % 6) + 3),
-    Math.PI / (($objkt.seed % 3) + 1),
+    width / ellipseWidth,
+    height / ellipseHeight,
+    Math.PI / (($objkt.seed % 2) + 1) / 2,
     0,
     2 * Math.PI
   );
@@ -46,6 +54,22 @@ function draw(width = window.innerWidth, height = window.innerHeight) {
   $objkt.capture();
 }
 
+function colorFeatures(color) {
+  const rgb = parseInt(color, 16);
+  const r = (rgb >> 16) & 0xff;
+  const g = (rgb >> 8) & 0xff;
+  const b = (rgb >> 0) & 0xff;
+  const lum = 0.2126 * r + 0.7152 * g + 0.0722 * b;
+
+  if (lum >= 80 && lum <= 100) {
+    return 'shade';
+  }
+  if (lum < 40) {
+    return 'dark';
+  }
+  return 'light';
+}
+
 function exportCanvas(mime) {
   return async ({ resolution: { x: x, y: y } }) => {
     draw(x, y);

snippet.js

@@ -2,19 +2,29 @@
 const query = new URLSearchParams(window.location.search);
 
 const $objkt = {
-  version: '0.0.1',
-  registerExport,
   _exports: {},
-  _exported: null,
+  _v: '0.0.1',
+  capture,
   isCapture: query.has('capture'),
+  registerExport,
+  registerFeatures,
   seed: Math.floor(Math.random() * Number.MAX_SAFE_INTEGER),
-  capture,
 };
 window.$objkt = $objkt;
 if (query.has('seed')) {
   $objkt.seed = parseInt(query.get('seed'), 16) % Number.MAX_SAFE_INTEGER;
 }
 
+function registerFeatures(features) {
+  if (typeof features === 'undefined') {
+    return ($objkt.features = null);
+  }
+  if (typeof features !== 'object' || Array.isArray(features)) {
+    throw new Error('registerFeatures expects an object');
+  }
+  return ($objkt.features = features);
+}
+
 function registerExport(args, fn) {
   const err = new Error(`Cannot register exporter for ${JSON.stringify(args)}`);
   if (typeof fn !== 'function') throw err;