import 'bootstrap.css';
import '@mescius/wijmo.styles/wijmo.css';
import './styles.css';
//
import { InputColor } from '@mescius/wijmo.input';
import { Color, toggleClass, format } from '@mescius/wijmo';
//
document.readyState === 'complete' ? init() : window.onload = init;
//
function init() {
// create InputColor controls
let cpFore = new InputColor('#icFore', {
value: 'black',
valueChanged: updateRatio
});
let cpBack = new InputColor('#icBack', {
value: 'white',
valueChanged: updateRatio
});
updateRatio();
// update the contrast ratio when the colors change
function updateRatio() {
// get lightness ratio
let lFore = getRelativeLuminance(cpFore.value);
let lBack = getRelativeLuminance(cpBack.value);
let ratio = (Math.max(lFore, lBack) + .05) / (Math.min(lFore, lBack) + 0.05);
// show sample text
let sample = document.querySelectorAll('.sample');
for (let i = 0; i < sample.length; i++) {
let style = sample[i].style;
style.color = cpFore.value;
style.background = cpBack.value;
}
// show the result
let e = document.getElementById('ratio');
e.innerHTML = format('<b>{ratio:g1}</b>:1', { ratio: ratio });
e.style.borderColor = ratio < 7 ? 'whitesmoke' : 'darkgreen';
pass('aa-normal', ratio >= 4.5);
pass('aa-large', ratio >= 3);
pass('aaa-normal', ratio >= 7);
pass('aaa-large', ratio >= 4.5);
}
function pass(id, pass) {
let e = document.getElementById(id);
e.textContent = pass ? 'Pass' : 'Fail';
toggleClass(e, 'fail', !pass);
}
// https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_Colors_and_Luminance
function getRelativeLuminance(color) {
let c = new Color(color);
let r = getChannel(c.r);
let g = getChannel(c.g);
let b = getChannel(c.b);
return (r * 0.2126 + g * 0.7152 + b * 0.0722);
}
function getChannel(rgb) {
rgb /= 255;
return rgb <= 0.03928
? rgb / 12.92
: Math.pow((rgb + 0.055) / 1.055, 2.4);
}
}
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>MESCIUS Wijmo InputColor Contrast Checker</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<!-- SystemJS -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.21.5/system.src.js" integrity="sha512-skZbMyvYdNoZfLmiGn5ii6KmklM82rYX2uWctBhzaXPxJgiv4XBwJnFGr5k8s+6tE1pcR1nuTKghozJHyzMcoA==" crossorigin="anonymous"></script>
<script src="systemjs.config.js"></script>
<script>
System.import('./src/app');
</script>
</head>
<body>
<div class="container-fluid">
<h1>
Contrast Checker
</h1>
<div class="row">
<div class="col-md-4">
<h3>
Foreground Color
</h3>
<div id="icFore"></div>
<h3>
Background Color
</h3>
<div id="icBack"></div>
</div>
<div class="col-md-4">
<h3>
Contrast Ratio
</h3>
<div id="ratio"></div>
<h3>
Result
</h3>
<p class="sample">
Normal Text
</p>
<p>
WCAG AA: <span id="aa-normal" class="result"></span>
WCAG AAA: <span id="aaa-normal" class="result"></span>
</p>
<p class="sample large">
Large Text
</p>
<p>
WCAG AA: <span id="aa-large" class="result"></span>
WCAG AAA: <span id="aaa-large" class="result"></span>
</p>
</div>
</div>
<h3>
Explanation
</h3>
<p>
WCAG 2.0 level AA requires a contrast ratio of at least 4.5:1 for normal text and
3:1 for large text.
</p>
<p>
WCAG 2.1 requires a contrast ratio of at least 3:1 for graphics and user interface
components (such as form input borders).
</p>
<p>
WCAG Level AAA requires a contrast ratio of at least 7:1 for normal text and 4.5:1
for large text.
</p>
<p>
For more details, please see
<a href="https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_Colors_and_Luminance" target="_blank">
The Science of Color Contrast
</a>.
</p>
</div>
</body>
</html>
#sample {
padding: 12px;
font-style: bold;
}
#ratio {
font-size: 200%;
padding: 12px;
font-style: bold;
text-align: center;
border-radius: 4px;
border: 2px solid whitesmoke;
}
.sample {
padding: 6px;
margin: 6px 0;
border: 2px solid whitesmoke;
}
.large {
font-size: 14pt;
font-weight: bold;
}
.result {
font-weight: bold;
margin-right: 2em;
padding: 3px 6px;
border-radius: 6px;
color: white;
background: darkgreen;
}
.result.fail {
background: darkred;
}
(function (global) {
System.config({
transpiler: 'plugin-babel',
babelOptions: {
es2015: true
},
meta: {
'*.css': { loader: 'css' }
},
paths: {
// paths serve as alias
'npm:': 'node_modules/'
},
// map tells the System loader where to look for things
map: {
'jszip': 'npm:jszip/dist/jszip.js',
'@mescius/wijmo': 'npm:@mescius/wijmo/index.js',
'@mescius/wijmo.input': 'npm:@mescius/wijmo.input/index.js',
'@mescius/wijmo.styles': 'npm:@mescius/wijmo.styles',
'@mescius/wijmo.cultures': 'npm:@mescius/wijmo.cultures',
'@mescius/wijmo.chart': 'npm:@mescius/wijmo.chart/index.js',
'@mescius/wijmo.chart.analytics': 'npm:@mescius/wijmo.chart.analytics/index.js',
'@mescius/wijmo.chart.animation': 'npm:@mescius/wijmo.chart.animation/index.js',
'@mescius/wijmo.chart.annotation': 'npm:@mescius/wijmo.chart.annotation/index.js',
'@mescius/wijmo.chart.finance': 'npm:@mescius/wijmo.chart.finance/index.js',
'@mescius/wijmo.chart.finance.analytics': 'npm:@mescius/wijmo.chart.finance.analytics/index.js',
'@mescius/wijmo.chart.hierarchical': 'npm:@mescius/wijmo.chart.hierarchical/index.js',
'@mescius/wijmo.chart.interaction': 'npm:@mescius/wijmo.chart.interaction/index.js',
'@mescius/wijmo.chart.radar': 'npm:@mescius/wijmo.chart.radar/index.js',
'@mescius/wijmo.chart.render': 'npm:@mescius/wijmo.chart.render/index.js',
'@mescius/wijmo.chart.webgl': 'npm:@mescius/wijmo.chart.webgl/index.js',
'@mescius/wijmo.chart.map': 'npm:@mescius/wijmo.chart.map/index.js',
'@mescius/wijmo.gauge': 'npm:@mescius/wijmo.gauge/index.js',
'@mescius/wijmo.grid': 'npm:@mescius/wijmo.grid/index.js',
'@mescius/wijmo.grid.detail': 'npm:@mescius/wijmo.grid.detail/index.js',
'@mescius/wijmo.grid.filter': 'npm:@mescius/wijmo.grid.filter/index.js',
'@mescius/wijmo.grid.search': 'npm:@mescius/wijmo.grid.search/index.js',
'@mescius/wijmo.grid.grouppanel': 'npm:@mescius/wijmo.grid.grouppanel/index.js',
'@mescius/wijmo.grid.multirow': 'npm:@mescius/wijmo.grid.multirow/index.js',
'@mescius/wijmo.grid.transposed': 'npm:@mescius/wijmo.grid.transposed/index.js',
'@mescius/wijmo.grid.transposedmultirow': 'npm:@mescius/wijmo.grid.transposedmultirow/index.js',
'@mescius/wijmo.grid.pdf': 'npm:@mescius/wijmo.grid.pdf/index.js',
'@mescius/wijmo.grid.sheet': 'npm:@mescius/wijmo.grid.sheet/index.js',
'@mescius/wijmo.grid.xlsx': 'npm:@mescius/wijmo.grid.xlsx/index.js',
'@mescius/wijmo.grid.selector': 'npm:@mescius/wijmo.grid.selector/index.js',
'@mescius/wijmo.grid.cellmaker': 'npm:@mescius/wijmo.grid.cellmaker/index.js',
'@mescius/wijmo.nav': 'npm:@mescius/wijmo.nav/index.js',
'@mescius/wijmo.odata': 'npm:@mescius/wijmo.odata/index.js',
'@mescius/wijmo.olap': 'npm:@mescius/wijmo.olap/index.js',
'@mescius/wijmo.rest': 'npm:@mescius/wijmo.rest/index.js',
'@mescius/wijmo.pdf': 'npm:@mescius/wijmo.pdf/index.js',
'@mescius/wijmo.pdf.security': 'npm:@mescius/wijmo.pdf.security/index.js',
'@mescius/wijmo.viewer': 'npm:@mescius/wijmo.viewer/index.js',
'@mescius/wijmo.xlsx': 'npm:@mescius/wijmo.xlsx/index.js',
'@mescius/wijmo.undo': 'npm:@mescius/wijmo.undo/index.js',
'@mescius/wijmo.interop.grid': 'npm:@mescius/wijmo.interop.grid/index.js',
'@mescius/wijmo.touch': 'npm:@mescius/wijmo.touch/index.js',
'@mescius/wijmo.cloud': 'npm:@mescius/wijmo.cloud/index.js',
'@mescius/wijmo.barcode': 'npm:@mescius/wijmo.barcode/index.js',
'@mescius/wijmo.barcode.common': 'npm:@mescius/wijmo.barcode.common/index.js',
'@mescius/wijmo.barcode.composite': 'npm:@mescius/wijmo.barcode.composite/index.js',
'@mescius/wijmo.barcode.specialized': 'npm:@mescius/wijmo.barcode.specialized/index.js',
'jszip': 'npm:jszip/dist/jszip.js',
'bootstrap.css': 'npm:bootstrap/dist/css/bootstrap.min.css',
'css': 'npm:systemjs-plugin-css/css.js',
'plugin-babel': 'npm:systemjs-plugin-babel/plugin-babel.js',
'systemjs-babel-build':'npm:systemjs-plugin-babel/systemjs-babel-browser.js'
},
// packages tells the System loader how to load when no filename and/or no extension
packages: {
src: {
defaultExtension: 'js'
},
"node_modules": {
defaultExtension: 'js'
},
}
});
})(this);
