参考：https://tomisan.com/2018/07/background-image-svg-color-sass-scss/

@function str-replace($string, $search, $replace: "") {
$index: str-index($string, $search);
@if $index {
@return str-slice($string, 1, $index - 1) + $replace + str-replace(str-slice($string, $index + str-length($search)), $search, $replace);
}
@return $string;
}

@function url-encode($string) {
$map: (
"%": "%25",
"<": "%3C", ">": "%3E",
" ": "%20",
"!": "%21",
"*": "%2A",
"'": "%27",
'"': "%22",
"(": "%28",
")": "%29",
";": "%3B",
":": "%3A",
"@": "%40",
"&": "%26",
"=": "%3D",
"+": "%2B",
"$": "%24",
",": "%2C",
"/": "%2F",
"?": "%3F",
"#": "%23",
"[": "%5B",
"]": "%5D"
);
$new: $string;
@each $search, $replace in $map {
$new: str-replace($new, $search, $replace);
}
@return $new;
}

//function
@function bg-svg($string) {
@return url('data:image/svg+xml;charset=utf8,#{url-encode($string)}');
}
//variable
$icon-color1: #CCC;
$icon-color2: #555;
//style
.icon-view {
background-image: bg-svg('');
}