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'use strict';
var postcss = require('postcss');
var objectAssign = require('object-assign');
var defaults = {
unitToConvert: 'px',
viewportWidth: 320,
viewportHeight: 568, // not now used; TODO: need for different units and math for different properties
unitPrecision: 5,
viewportUnit: 'vw',
fontViewportUnit: 'vw', // vmin is more suitable.
selectorBlackList: [],
minPixelValue: 1,
mediaQuery: false,
replace: true
};
module.exports = postcss.plugin('postcss-px-to-viewport', function (options) {
var opts = objectAssign({}, defaults, options);
var pxReplace = createPxReplace(opts.viewportWidth, opts.minPixelValue, opts.unitPrecision, opts.viewportUnit);
// excluding regex trick: http://www.rexegg.com/regex-best-trick.html
// Not anything inside double quotes
// Not anything inside single quotes
// Not anything inside url()
// Any digit followed by px
// !singlequotes|!doublequotes|!url()|pixelunit
var pxRegex = new RegExp('"[^"]+"|\'[^\']+\'|url\\([^\\)]+\\)|(\\d*\\.?\\d+)' + opts.unitToConvert, 'ig')
return function (css) {
css.walkDecls(function (decl, i) {
// This should be the fastest test and will remove most declarations
if (decl.value.indexOf(opts.unitToConvert) === -1) return;
if (blacklistedSelector(opts.selectorBlackList, decl.parent.selector)) return;
var unit = getUnit(decl.prop, opts);
var value = decl.value.replace(pxRegex, createPxReplace(opts.viewportWidth, opts.minPixelValue, opts.unitPrecision, unit));
if (declarationExists(decl.parent, decl.prop, value)) return;
if (opts.replace) {
decl.value = value;
} else {
decl.parent.insertAfter(i, decl.clone({ value: value }));
}
});
if (opts.mediaQuery) {
css.walkAtRules('media', function (rule) {
if (rule.params.indexOf(opts.unitToConvert) === -1) return;
rule.params = rule.params.replace(pxRegex, pxReplace);
});
}
};
});
function getUnit(prop, opts) {
return prop.indexOf('font') === -1 ? opts.viewportUnit : opts.fontViewportUnit;
}
function createPxReplace(viewportSize, minPixelValue, unitPrecision, viewportUnit) {
return function (m, $1) {
if (!$1) return m;
var pixels = parseFloat($1);
if (pixels <= minPixelValue) return m;
return toFixed((pixels / viewportSize * 100), unitPrecision) + viewportUnit;
};
}
function toFixed(number, precision) {
var multiplier = Math.pow(10, precision + 1),
wholeNumber = Math.floor(number * multiplier);
return Math.round(wholeNumber / 10) * 10 / multiplier;
}
function blacklistedSelector(blacklist, selector) {
if (typeof selector !== 'string') return;
return blacklist.some(function (regex) {
if (typeof regex === 'string') return selector.indexOf(regex) !== -1;
return selector.match(regex);
});
}
function declarationExists(decls, prop, value) {
return decls.some(function (decl) {
return (decl.prop === prop && decl.value === value);
});
}