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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/astrobench@0.1.2/src/style.css">
<script src="../test/lib/rollup.browser.js"></script>
<script src="../test/lib/requireES.js"></script>
<script src="../test/lib/config.js"></script>
<script src="../test/data/text.js"></script>
<title>measureText</title>
</head>
<body>
<div id="astrobench"></div>
<script src="https://cdn.jsdelivr.net/npm/astrobench@0.1.2/dist/astrobench.js"></script>
<script type="text/javascript">
requireES([
'zrender/esm/core/LRU'
], function (LRU) {
function createMeasure() {
let ctx = document.createElement('canvas').getContext('2d');
let lastFont;
return function getWidth(text, font) {
if (lastFont !== font) {
ctx.font = font;
lastFont = font;
}
return ctx.measureText(text).width;
}
}
function createMeasureSimpleCache() {
let textWidthCache = {};
let textWidthCacheCounter = 0;
const getWidth = createMeasure();
const TEXT_CACHE_MAX = 5000;
return function getWidthSimpleCache(text, font) {
const key = text + ':' + font;
if (textWidthCache[key]) {
return textWidthCache[key];
}
const width = getWidth(text, font);
if (textWidthCacheCounter > TEXT_CACHE_MAX) {
textWidthCacheCounter = 0;
textWidthCache = {};
}
textWidthCacheCounter++;
textWidthCache[key] = width;
return width;
}
}
function createMeasureLRUCache() {
let textWidthCache = {};
const getWidth = createMeasure();
return function getWidthLRUCache(text, font) {
let cacheOfFont = textWidthCache[font];
if (!cacheOfFont) {
cacheOfFont = textWidthCache[font] = new LRU.default(500);
}
let width = cacheOfFont.get(text);
if (width == null) {
width = getWidth(text, font);
cacheOfFont.put(text, width);
}
return width;
}
}
function createSuite(name, textFrags) {
suite(name, function () {
let font = '12px sans-serif';
let basicMeasure;
let measureWithSimpleCache;
let measureWithLRUCache;
setup(function () {
basicMeasure = createMeasure();
measureWithSimpleCache = createMeasureSimpleCache();
measureWithLRUCache = createMeasureLRUCache();
let testRes1 = basicMeasure('测试', font);
let testRes2 = measureWithSimpleCache('测试', font);
let testRes3 = measureWithLRUCache('测试', font);
if (testRes1 !== testRes2 || testRes1 !== testRes3) {
throw new Error(`Result wrong, ${testRes1}, ${testRes2}, ${testRes3}`);
}
});
bench('Basic', function () {
for (let i = 0; i < textFrags.length; i++) {
let width = basicMeasure(textFrags[i], font);
}
});
bench('Simple Cache', function () {
// TODO 如果 measureWithSimpleCache 调用报错，会报 textFrags is not defined 的错误
for (let i = 0; i < textFrags.length; i++) {
let width = measureWithSimpleCache(textFrags[i], font);
}
});
bench('LRU Cache', function () {
for (let i = 0; i < textFrags.length; i++) {
let width = measureWithLRUCache(textFrags[i], font);
}
});
});
}
createSuite('English Measure Text(By Words)', LARGE_TEXT_EN.split(' '));
createSuite('English Measure Text(By Character)', LARGE_TEXT_EN.split(''));
createSuite('Chinese Measure Text', LARGE_TEXT_ZH.split(''));
});
</script>
</body>
</html>
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