Less 函数

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Less 函数

2023-03-14 11:22| 来源: 网络整理| 查看: 265

Edit the markdown source for "misc-functions" color

Parses a color, so a string representing a color becomes a color.

Parameters: string: a string of the specified color.

Returns: color

Example: color("#aaa");

Output: #aaa

image-size

Gets the image dimensions from a file.

Parameters: string: the file to get the dimensions for.

Returns: dimension

Example: image-size("file.png");

Output: 10px 10px

Note: this function needs to be implemented by each environment. It is currently only available in the node environment.

Added in: v2.2.0

image-width

Gets the image width from a file.

Parameters: string: the file to get the dimensions for.

Returns: dimension

Example: image-width("file.png");

Output: 10px

Note: this function needs to be implemented by each environment. It is currently only available in the node environment.

Added in: v2.2.0

image-height

Gets the image height from a file.

Parameters: string: the file to get the dimensions for.

Returns: dimension

Example: image-height("file.png");

Output: 10px

Note: this function needs to be implemented by each environment. It is currently only available in the node environment.

Added in: v2.2.0

convert

Convert a number from one unit into another.

The first argument contains a number with units and second argument contains units. If the units are compatible, the number is converted. If they are not compatible, the first argument is returned unmodified.

See unit for changing the unit without conversion.

Compatible unit groups:

lengths: m, cm, mm, in, pt and pc, time: s and ms, angle: rad, deg, grad and turn.

Parameters:

number: a floating point number with units. identifier, string or escaped value: units

Returns: number

Example:

convert(9s, "ms") convert(14cm, mm) convert(8, mm) // incompatible unit types

Output:

9000ms 140mm 8 data-uri

Inlines a resource and falls back to url() if the ieCompat option is on and the resource is too large, or if you use the function in the browser. If the MIME type is not given then node uses the mime package to determine the correct mime type.

Parameters:

mimetype: (Optional) A MIME type string. url: The URL of the file to inline.

If there is no mimetype, data-uri function guesses it from filename suffix. Text and svg files are encoded as utf-8 and anything else is encoded as base64.

If user provided mimetype, the function uses base64 if mimetype argument ends with ;base64. For example, image/jpeg;base64 is encoded into base64 while text/html is encoded into utf-8.

Example: data-uri('../data/image.jpg');

Output: url('data:image/jpeg;base64,bm90IGFjdHVhbGx5IGEganBlZyBmaWxlCg==');

Output in browser: url('../data/image.jpg');

Example: data-uri('image/jpeg;base64', '../data/image.jpg');

Output: url('data:image/jpeg;base64,bm90IGFjdHVhbGx5IGEganBlZyBmaWxlCg==');

Example: data-uri('image/svg+xml;', 'image.svg');

Output: url("data:image/svg+xml;charset=UTF-8,%3Csvg%3E%3Ccircle%20r%3D%229%22%2F%3E%3C%2Fsvg%3E");

default

Available only inside guard conditions and returns true only if no other mixin matches, false otherwise.

Example:

.mixin(1) {x: 11} .mixin(2) {y: 22} .mixin(@x) when (default()) {z: @x} div { .mixin(3); } div.special { .mixin(1); }

Output:

div { z: 3; } div.special { x: 11; }

It is possible to use the value returned by default with guard operators. For example .mixin() when not(default()) {} will match only if there's at least one more mixin definition that matches.mixin() call:

.mixin(@value) when (ispixel(@value)) {width: @value} .mixin(@value) when not(default()) {padding: (@value / 5)} div-1 { .mixin(100px); } div-2 { /* ... */ .mixin(100%); }

result:

div-1 { width: 100px; padding: 20px; } div-2 { /* ... */ }

It is allowed to make multiple default() calls in the same guard condition or in a different conditions of a mixins with the same name:

div { .m(@x) when (default()), not(default()) {always: @x} .m(@x) when (default()) and not(default()) {never: @x} .m(1); // OK }

However Less will throw a error if it detects a potential conflict between multiple mixin definitions using default():

div { .m(@x) when (default()) {} .m(@x) when not(default()) {} .m(1); // Error }

In above example it is impossible to determine what value each default() call should return since they recursively depend on each other.

Advanced multiple default() usage:

.x { .m(red) {case-1: darkred} .m(blue) {case-2: darkblue} .m(@x) when (iscolor(@x)) and (default()) {default-color: @x} .m('foo') {case-1: I am 'foo'} .m('bar') {case-2: I am 'bar'} .m(@x) when (isstring(@x)) and (default()) {default-string: and I am the default} &-blue {.m(blue)} &-green {.m(green)} &-foo {.m('foo')} &-baz {.m('baz')} }

Result:

.x-blue { case-2: #00008b; } .x-green { default-color: #008000; } .x-foo { case-1: I am 'foo'; } .x-baz { default-string: and I am the default; }

The default function is available as a Less built-in function only inside guard expressions. If used outside of a mixin guard condition it is interpreted as a regular CSS value:

Example:

div { foo: default(); bar: default(42); }

Result:

div { foo: default(); bar: default(42); } unit

Remove or change the unit of a dimension

Parameters:

dimension: A number, with or without a dimension. unit: (Optional) the unit to change to, or if omitted it will remove the unit.

See convert for changing the unit with conversion.

Example: unit(5, px)

Output: 5px

Example: unit(5em)

Output: 5

get-unit

Returns units of a number.

If the argument contains a number with units, the function returns its units. The argument without units results in an empty return value.

Parameters:

number: a number with or without units.

Example: get-unit(5px)

Output: px

Example: get-unit(5)

Output: //nothing

svg-gradient

Generates multi-stop svg gradients.

Svg-gradient function generates multi-stop svg gradients. It must have at least three parameters. First parameter specifies gradient type and direction and remaining parameters list colors and their positions. The position of first and last specified color are optional, remaining colors must have positions specified.

The direction must be one of to bottom, to right, to bottom right, to top right, ellipse or ellipse at center. The direction can be specified as both escaped value ~'to bottom' and space separated list of words to bottom.

The direction must be followed by two or more color stops. They can be supplied either inside a list or you can specify each color stops in separate argument.

Parameters - colors stops in list:

escaped value or list of identifiers: direction list - all colors and their positions in list

Parameters - color stops in arguments:

escaped value or list of identifiers: direction color [percentage] pair: first color and its relative position (position is optional) color percent pair: (optional) second color and its relative position ... color percent pair: (optional) n-th color and its relative position color [percentage] pair: last color and its relative position (position is optional)

Returns: url with "URI-Encoded" svg gradient.

Example - colors stops in list:

div { @list: red, green 30%, blue; background-image: svg-gradient(to right, @list); }

equivalent - color stops in arguments:

div { background-image: svg-gradient(to right, red, green 30%, blue); }

both result in:

div { background-image: url('data:image/svg+xml,%3C%3Fxml%20version%3D%221.0%22%20%3F%3E%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20version%3D%221.1%22%20width%3D%22100%25%22%20height%3D%22100%25%22%20viewBox%3D%220%200%201%201%22%20preserveAspectRatio%3D%22none%22%3E%3ClinearGradient%20id%3D%22gradient%22%20gradientUnits%3D%22userSpaceOnUse%22%20x1%3D%220%25%22%20y1%3D%220%25%22%20x2%3D%22100%25%22%20y2%3D%220%25%22%3E%3Cstop%20offset%3D%220%25%22%20stop-color%3D%22%23ff0000%22%2F%3E%3Cstop%20offset%3D%2230%25%22%20stop-color%3D%22%23008000%22%2F%3E%3Cstop%20offset%3D%22100%25%22%20stop-color%3D%22%230000ff%22%2F%3E%3C%2FlinearGradient%3E%3Crect%20x%3D%220%22%20y%3D%220%22%20width%3D%221%22%20height%3D%221%22%20fill%3D%22url(%23gradient)%22%20%2F%3E%3C%2Fsvg%3E'); }

Note: in versions before 2.2.0 the result is base64 encoded .

Generated background image has red color on the left, green at 30% of its width and ends with a blue color. Base64 encoded part contains following svg-gradient:

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