code: @ColorInt public static int increaseOpacity(Context context, @ColorRes int res, int alpha) {
          int c = resolveColor(res, context);
          return increaseOpacityFromInt(context, resolveColor(res, context), alpha);
      }
docs: Lightens a color by increasing its alpha channel value
  
  @param context the current context
  @param res     the color resource
  @param alpha   the alpha to set
  @return a color int