postcss-pixel-to-viewport

A plugin for PostCSS that generates viewport units (vw, vh, vmin, vmax) from pixel units.

Usage

If your project involves a fixed width, this script will help to convert pixels into viewport units.

Input/Output

// input

.class {
  margin: -10px .5vh;
  padding: 5vmin 9.5px 1px;
  border: 3px solid black;
  border-bottom-width: 1px;
  font-size: 14px;
  line-height: 20px;/*off*/
}

.class2 {
  border: 1px solid black;
  margin-bottom: 1px;
  font-size: 20px;
  line-height: 30px;
}

@media (min-width: 750px) {
  .class3 {
    font-size: 16px;
    line-height: 22px;
  }
}

// output

.class {
  margin: -1.33333vmin .5vh;
  padding: 5vmin 1.26667vmin 1px;
  border: 0.4vmin solid black;
  border-bottom-width: 1px;
  font-size: 1.86667vmin;
  line-height: 20px;
}

.class2 {
  border: 1px solid black;
  margin-bottom: 1px;
  font-size: 2.66667vmin;
  line-height: 4vmin;
}

@media (min-width: 750px) {
  .class3 {
    font-size: 2.13333vmin;
    line-height: 2.93333vmin;
  }
}

Example

'use strict';

var fs = require('fs');
var postcss = require('postcss');
var px2viewport = require('..');
var css = fs.readFileSync('main.css', 'utf8');
var options = {
  propList: ['font-size']
};
var processedCss = postcss(px2viewport(options)).process(css).css;

fs.writeFile('main-viewport.css', processedCss, function (err) {
  if (err) {
    throw err;
  }
  console.log('File with viewport units written.');
});

Options

Default:

{
  unitToConvert: 'px',
  viewportWidth: 320,
  viewportHeight: 568,
  unitPrecision: 5,
  viewportUnit: 'vw',
  fontViewportUnit: 'vw',  // vmin is more suitable.
  selectorBlackList: [],
  propList: ['*'],
  minPixelValue: 1,
  mediaQuery: false,
  replace: true,
  landscape: false,
  landscapeUnit: 'vw',
  landscapeWidth: 568,
  mediaMinWidth: 767.98,
  disableConvertComment: 'off',
}

• unitToConvert (String) unit to convert, by default, it is px.
• viewportWidth (Number) The width of the viewport.
• unitPrecision (Number) The decimal numbers to allow the vw units to grow to.
• propList (Array) The properties that can change from px to vw.
  • Values need to be exact matches.
  • Use wildcard * to enable all properties. Example: ['*']
  • Use * at the start or end of a word. (['position'] will match background-position-y)
  • Use ! to not match a property. Example: ['*', '!letter-spacing']
  • Combine the "not" prefix with the other prefixes. Example: ['', '!font']
• viewportUnit (String) Expected units.
• fontViewportUnit (String) Expected units for font.
• selectorBlackList (Array) The selectors to ignore and leave as px.
  • If value is string, it checks to see if selector contains the string.
    • ['body'] will match .body-class
  • If value is regexp, it checks to see if the selector matches the regexp.
    • [/^body$/] will match body but not .body
• minPixelValue (Number) Set the minimum pixel value to replace.
• mediaQuery (Boolean) Allow px to be converted in media queries.
• replace (Boolean) replaces rules containing vw instead of adding fallbacks.
• exclude (Array or Regexp) Ignore some files like 'node_modules'
  • If value is regexp, will ignore the matches files.
  • If value is array, the elements of the array are regexp.
• landscape (Boolean) Adds @media (orientation: landscape) with values converted via landscapeWidth.
• landscapeUnit (String) Expected unit for landscape option
• landscapeWidth (Number) Viewport width for landscape orientation.
• disableConvertComment (String) content of comment for disable convert px unit before the declaration.

Use comment to enable/disable convert px value for single declaration

• font-size: 14px;/*off*/ comment before the declaration will not convert px unit.

Use with gulp-postcss

var gulp = require('gulp');
var postcss = require('gulp-postcss');
var px2viewport = require('postcss-pixel-to-viewport');

gulp.task('css', function () {
  var processors = [
    px2viewport({
      viewportWidth: 750
    })
  ];
  return gulp.src(['build/css/**/*.css'])
    .pipe(postcss(processors))
    .pipe(gulp.dest('build/css'));
});