Postcss-adaptive NPM

postcss-adaptive

A postcss plugin that calculates and generates adaptive css code, such as rem and 0.5px borders for retina devices.

Requirements

Set rem unit and hairline class. For example:

(function (win, doc) {
  var docEl = doc.documentElement;

  function setRemUnit () {
    var docWidth = docEl.clientWidth;
    var rem = docWidth / 10;
    docEl.style.fontSize = rem + 'px';
  }

  win.addEventListener('resize', function () {
    setRemUnit();
  }, false);
  win.addEventListener('pageshow', function (e) {
    if (e.persisted) {
      setRemUnit();
    }
  }, false);

  setRemUnit();

  if (win.devicePixelRatio && win.devicePixelRatio >= 2) {
    var testEl = doc.createElement('div');
    var fakeBody = doc.createElement('body');
    testEl.style.border = '0.5px solid transparent';
    fakeBody.appendChild(testEl);
    docEl.appendChild(fakeBody);
    if (testEl.offsetHeight === 1) {
      docEl.classList.add('hairlines');
    }
    docEl.removeChild(fakeBody);
  }
}) (window, document);

Usage

The raw stylesheet only contains @2x style, and if you

intend to use rem unit，add /*rem*/ after the declaration
don't intend to transform the original value, add /*no*/ after the declaration
intend to use px unit when autoRem is set to true, add /*px*/ after the declaration

Attention: Dealing with SASS or LESS, only /*...*/ comment can be used, in order to have the comments persisted.

Before processing:

.selector {
  height: 64px;
  width: 150px; /*rem*/
  padding: 10px; /*no*/
  border-top: 1px solid #ddd;
}

After processing:

.selector {
  height: 32px;
  width: 2rem;
  padding: 10px;
  border-top: 1px solid #ddd;
}
.hairlines .selector {
  border-top: 0.5px solid #ddd;
}

API

adaptive(config)

Config:

remUnit: number, rem unit value (default: 75)
baseDpr: number, base device pixel ratio (default: 2)
remPrecision: number, rem value precision (default: 6)
hairlineClass: string, class name of 1px border (default 'hairlines')
autoRem: boolean, whether to transform to rem unit (default: false)

Node

npm install postcss-adaptive

var postcss = require('postcss');
var adaptive = require('postcss-adaptive');
var originCssText = '...';
var newCssText = postcss().use(adaptive({ remUnit: 75 })).process(originCssText).css;

Gulp

var gulp = require('gulp');
var postcss = require('gulp-postcss');
var adaptive = require('postcss-adaptive');

gulp.task('default', function () {
  var processors = [adaptive({ remUnit: 75 })];
  return gulp.src('./src/*.css')
    .pipe(postcss(processors))
    .pipe(gulp.dest('./dest'));
});

Webpack

var adaptive = require('postcss-adaptive');

module.exports = {
  module: {
    loaders: [
      {
        test: /\.css$/,
        loader: "style-loader!css-loader!postcss-loader"
      }
    ]
  },
  postcss: function () {
    return [adaptive({ remUnit: 75 })];
  }
}

Grunt

module.exports = function (grunt) {
  grunt.initConfig({
    postcss: {
      options: {
        processors: [
          adaptive({ remUnit: 75 })
        ]
      },
      dist: {
        src: 'src/*.css',
        dest: 'build'
      }
    }
  });
  grunt.loadNpmTasks('grunt-postcss');
  grunt.registerTask('default', ['postcss']);
}