anki/sass/elevation.scss

// Heavily inspired by https://github.com/material-components/material-components-web/tree/master/packages/mdc-elevation
@use "sass:map";
@use "sass:list";

/**
 * The maps correspond to dp levels:
 * 0: 0dp
 * 1: 1dp
 * 2: 2dp
 * 3: 3dp
 * 4: 4dp
 * 5: 6dp
 * 6: 8dp
 * 7: 12dp
 * 8: 16dp
 * 9: 24dp
 */

$umbra-map: (
    0: "0px 0px 0px 0px",
    1: "0px 2px 1px -1px",
    2: "0px 3px 1px -2px",
    3: "0px 3px 3px -2px",
    4: "0px 2px 4px -1px",
    5: "0px 3px 5px -1px",
    6: "0px 5px 5px -3px",
    7: "0px 7px 8px -4px",
    8: "0px 8px 10px -5px",
    9: "0px 11px 15px -7px",
);

$penumbra-map: (
    0: "0px 0px 0px 0px",
    1: "0px 1px 1px 0px",
    2: "0px 2px 2px 0px",
    3: "0px 3px 4px 0px",
    4: "0px 4px 5px 0px",
    5: "0px 6px 10px 0px",
    6: "0px 8px 10px 1px",
    7: "0px 12px 17px 2px",
    8: "0px 16px 24px 2px",
    9: "0px 24px 38px 3px",
);

$ambient-map: (
    0: "0px 0px 0px 0px",
    1: "0px 1px 3px 0px",
    2: "0px 1px 5px 0px",
    3: "0px 1px 8px 0px",
    4: "0px 1px 10px 0px",
    5: "0px 1px 18px 0px",
    6: "0px 3px 14px 2px",
    7: "0px 5px 22px 4px",
    8: "0px 6px 30px 5px",
    9: "0px 9px 46px 8px",
);

$umbra-opacity: 0.2;
$penumbra-opacity: 0.14;
$ambient-opacity: 0.12;

@function box-shadow($level, $opacity-boost: 0, $color: black) {
    $umbra-z-value: map.get($umbra-map, $level);
    $penumbra-z-value: map.get($penumbra-map, $level);
    $ambient-z-value: map.get($ambient-map, $level);

    $umbra-color: rgba($color, $umbra-opacity + $opacity-boost);
    $penumbra-color: rgba($color, $penumbra-opacity + $opacity-boost);
    $ambient-color: rgba($color, $ambient-opacity + $opacity-boost);

    @return (
        #{"#{$umbra-z-value} #{$umbra-color}"},
        #{"#{$penumbra-z-value} #{$penumbra-color}"},
        #{$ambient-z-value} $ambient-color
    );
}

@mixin elevation($level, $other: ()) {
    box-shadow: list.join(box-shadow($level), $other);
}