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<!DOCTYPE html>
<meta charset="utf-8">
<title>Length unit 'ch' used in pseudo elements should be recalculated after loading a web font</title>
<link rel="help" href="https://www.w3.org/TR/css-font-loading-3/#font-face-load">
<link rel="help" href="https://www.w3.org/TR/css-values-3/#font-relative-lengths">
<link rel="help" href="https://drafts.csswg.org/css-pseudo-4/#first-letter-styling">
<link rel="author" href="xiaochengh@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.container {
font: 25px/1 "custom font", monospace;
}
.before::before,
.after::after,
.first-letter::first-letter,
.first-line::first-line {
font-family: monospace;
font-size: 1ch; /* Refers to originating element's font metrics, which are different from self font metrics. */
}
.before::before,
.after::after {
content: 'text';
}
/* Defined separately so that browsers that haven't shipped it can still pass other tests. */
.marker::marker {
font-family: monospace;
font-size: 1ch;
content: 'text';
}
</style>
<div class="container before"></div>
<div class="container after"></div>
<div class="container first-letter">text</div>
<div class="container first-line">text</div>
<li class="container marker"></li>
<script>
function parseFontSizeInPx(element, pseudoElement) {
const value = getComputedStyle(element, pseudoElement).fontSize;
if (!value.endsWith('px'))
return NaN;
return parseFloat(value);
}
const testCases = ['before', 'after', 'first-letter', 'first-line', 'marker'];
const elements = testCases.map(testCase => document.querySelector('.' + testCase));
const asyncTests = testCases.map(
testCase => async_test(`ch in pseudo-element ::${testCase} should be recalculated after loading a web font`));
// Before loading custom font, tests should be rendered with monospace
// fallback and have a '1ch' measurement much shorter than 25px.
for (let i = 0; i < testCases.length; ++i) {
asyncTests[i].step(() => {
const fontSizePx = parseFontSizeInPx(elements[i], '::' + testCases[i]);
assert_less_than(fontSizePx, 24);
});
}
// Insert custom font into style sheet and load it
const customFont = new FontFace('custom font', 'url(/fonts/Ahem.ttf)');
document.fonts.add(customFont);
// After loading custom font, tests should be rendered with the custom font,
// which is Ahem, and have a '1ch' measurement that equals 25px.
customFont.load().then(
() => {
for (let i = 0; i < testCases.length; ++i) {
asyncTests[i].step(() => {
const fontSizePx = parseFontSizeInPx(elements[i], '::' + testCases[i]);
assert_approx_equals(fontSizePx, 25, 0.1);
asyncTests[i].done();
});
}
},
() => {
for (let i = 0; i < testCases.length; ++i) {
asyncTests[i].step(() => {
assert_unreached('Failed to load font');
});
}
}
);
</script>
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