scss RGB-2-rgba.scss

Posted 2021-05-18

// 152 converts to an alpha value of (255 - 152) / 255 ~ 0.404

// 152 scales using (152 - 152) / 0.404 = 0
// 177 scales using (177 - 152) / 0.404 ~ 62
// 202 scales using (202 - 152) / 0.404 ~ 123
// So, rgb(152, 177, 202) displays as rgba(0, 62, 123, .404).

@function _rgba($color) {
  $r: red($color);
  $g: green($color);
  $b: blue($color);

  $min: min($r, $g, $b);
  $scale: (255 - $min) / 255;

  @return rgba(
    (($r - $min) / $scale),
    (($g - $min) / $scale),
    (($b - $min) / $scale),
    $scale
  );
}