| 1 | @charset "UTF-8"; |
| 2 | |
| 3 | /// Switches between two colors based on the contrast to another color. It’s |
| 4 | /// like a [ternary operator] for color contrast and can be useful for building |
| 5 | /// a button system. |
| 6 | /// |
| 7 | /// The calculation of the contrast ratio is based on the [WCAG 2.0 |
| 8 | /// specification]. However, we cannot guarantee full compliance, though all of |
| 9 | /// our manual testing passed. |
| 10 | /// |
| 11 | /// [ternary operator]: https://goo.gl/ccfLqi |
| 12 | /// [WCAG 2.0 specification]: https://goo.gl/zhQuYA |
| 13 | /// |
| 14 | /// @argument {color} $base-color |
| 15 | /// The color to evaluate lightness against. |
| 16 | /// |
| 17 | /// @argument {color} $dark-color [#000] |
| 18 | /// The color to be output when `$base-color` is light. Can also be set |
| 19 | /// globally using the `contrast-switch-dark-color` key in the |
| 20 | /// Bourbon settings. |
| 21 | /// |
| 22 | /// @argument {color} $light-color [#fff] |
| 23 | /// The color to be output when `$base-color` is dark. Can also be set |
| 24 | /// globally using the `contrast-switch-light-color` key in the |
| 25 | /// Bourbon settings. |
| 26 | /// |
| 27 | /// @return {color} |
| 28 | /// |
| 29 | /// @example scss |
| 30 | /// .element { |
| 31 | /// color: contrast-switch(#bae6e6); |
| 32 | /// } |
| 33 | /// |
| 34 | /// // CSS Output |
| 35 | /// .element { |
| 36 | /// color: #000; |
| 37 | /// } |
| 38 | /// |
| 39 | /// @example scss |
| 40 | /// .element { |
| 41 | /// $button-color: #2d72d9; |
| 42 | /// background-color: $button-color; |
| 43 | /// color: contrast-switch($button-color, #222, #eee); |
| 44 | /// } |
| 45 | /// |
| 46 | /// // CSS Output |
| 47 | /// .element { |
| 48 | /// background-color: #2d72d9; |
| 49 | /// color: #eee; |
| 50 | /// } |
| 51 | /// |
| 52 | /// @require {function} _fetch-bourbon-setting |
| 53 | /// |
| 54 | /// @require {function} _is-color |
| 55 | /// |
| 56 | /// @require {function} _contrast-ratio |
| 57 | /// |
| 58 | /// @since 5.0.0 |
| 59 | |
| 60 | @function contrast-switch( |
| 61 | $base-color, |
| 62 | $dark-color: _fetch-bourbon-setting("contrast-switch-dark-color"), |
| 63 | $light-color: _fetch-bourbon-setting("contrast-switch-light-color") |
| 64 | ) { |
| 65 | @if not _is-color($base-color) { |
| 66 | @error "`#{$base-color}` is not a valid color for the `$base-color` " + |
| 67 | "argument in the `contrast-switch` function."; |
| 68 | } @else if not _is-color($dark-color) { |
| 69 | @error "`#{$dark-color}` is not a valid color for the `$dark-color` " + |
| 70 | "argument in the `contrast-switch` function."; |
| 71 | } @else if not _is-color($light-color) { |
| 72 | @error "`#{$light-color}` is not a valid color for the `$light-color` " + |
| 73 | "argument in the `contrast-switch` function."; |
| 74 | } @else { |
| 75 | $-contrast-to-dark: _contrast-ratio($base-color, $dark-color); |
| 76 | $-contrast-to-light: _contrast-ratio($base-color, $light-color); |
| 77 | $-prefer-dark: $-contrast-to-dark >= $-contrast-to-light; |
| 78 | |
| 79 | @return if($-prefer-dark, $dark-color, $light-color); |
| 80 | } |
| 81 | } |