First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/khroma/src/methods/mix.ts

@@ -0,0 +1,33 @@
+
+/* IMPORT */
+
+import Color from '~/color';
+import rgba from '~/methods/rgba';
+import type {Channels} from '~/types';
+
+/* MAIN */
+
+//SOURCE: https://github.com/sass/dart-sass/blob/7457d2e9e7e623d9844ffd037a070cf32d39c348/lib/src/functions/color.dart#L718-L756
+
+const mix = ( color1: string | Channels, color2: string | Channels, weight: number = 50 ): string => {
+
+  const {r: r1, g: g1, b: b1, a: a1} = Color.parse ( color1 );
+  const {r: r2, g: g2, b: b2, a: a2} = Color.parse ( color2 );
+  const weightScale = weight / 100;
+  const weightNormalized = ( weightScale * 2 ) - 1;
+  const alphaDelta = a1 - a2;
+  const weight1combined = ( ( weightNormalized * alphaDelta ) === -1 ) ? weightNormalized : ( weightNormalized + alphaDelta ) / ( 1 + weightNormalized * alphaDelta );
+  const weight1 = ( weight1combined + 1 ) / 2;
+  const weight2 = 1 - weight1;
+  const r = ( r1 * weight1 ) + ( r2 * weight2 );
+  const g = ( g1 * weight1 ) + ( g2 * weight2 );
+  const b = ( b1 * weight1 ) + ( b2 * weight2 );
+  const a = ( a1 * weightScale ) + ( a2 * ( 1 - weightScale ) );
+
+  return rgba ( r, g, b, a );
+
+};
+
+/* EXPORT */
+
+export default mix;