postcss-at2x 

Ported from rework-plugin-at2x

Installation

``console
$ npm install postcss postcss-at2x --save-dev
`

Usage

`js
const fs = require('fs');
const postcss = require('postcss');
const at2x = require('postcss-at2x');

const input = fs.readFileSync('input.css', 'utf8');

const output = postcss()
.use(at2x())
.process(input)
.then(result => console.log(result.css));
`

$3

Adds at-2x keyword to background and background-image declarations to add retina support for images.

Input

`css
.multi {
background: url(http://example.com/image.png),
linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 1)),
green,
url(/public/images/cool.png) at-2x;
}
`

Output

`css
.multi {
background: url(http://example.com/image.png),
linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 1)),
green,
url(/public/images/cool.png);
}

@media (min-device-pixel-ratio: 1.5), (min-resolution: 144dpi), (min-resolution: 1.5dppx) {
.multi {
background-image: url(http://example.com/image.png),
linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 1)),
none,
url(/public/images/cool@2x.png);
}
}
`

$3

##### identifier (default: "@2x") _string_

Change the identifier added to retina images, for example file@2x.png can be file-retina.png.

##### detectImageSize (default: false) _boolean_

Obtains the image dimensions of the non-retina image automatically and applies them to the
background-size property of the retina image.

##### skipMissingRetina (default: false) _boolean_

If the retina image cannot be found on the file system it will be skipped and
not output into the result CSS.

##### resolveImagePath _function_

Get resolved image path for detecting image size. By default, original url value is resolved from current working directory (process.cwd()).

Function receives two arguments: original url value and PostCSS declaration source.

Output

`css
.element {
background: url(img.jpg) no-repeat;
}

@media (min-device-pixel-ratio: 1.5), (min-resolution: 144dpi), (min-resolution: 1.5dppx) {
.element {
background: url(img@2x.jpg) no-repeat;
background-size: 540px 675px; / Dimensions of img.jpg /
}
}
``

See PostCSS docs for examples for your environment.