{"id":374,"date":"2024-12-08T13:41:36","date_gmt":"2024-12-08T05:41:36","guid":{"rendered":"\/?p=374"},"modified":"2024-12-08T13:41:39","modified_gmt":"2024-12-08T05:41:39","slug":"javascript-canva%e5%b1%9e%e6%80%a7","status":"publish","type":"post","link":"\/?p=374","title":{"rendered":"JavaScript-canva\u5c5e\u6027"},"content":{"rendered":"\n<p><a href=\"https:\/\/www.w3school.com.cn\/tags\/html_ref_canvas.asp\">https:\/\/www.w3school.com.cn\/tags\/html_ref_canvas.asp<\/a><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5faa\u73af\u753b\u5706\u7a0b\u5e8f<\/h3>\n\n\n\n<pre class=\"wp-block-code\"><code>function sleep(time){\n    return new Promise(function(resolve){\n        setTimeout(resolve,time)\n    })\n    \/\/\u5ef6\u8fdf\u5f02\u6b65\u51fd\u6570\n}\n\nasync function drow() {\n    let ctx = document.getElementById('drows').getContext('2d')\n    ctx.clearRect(0, 0, 300, 300);\n    \/\/\u6e05\u9664\u753b\u5e03\n    for(var i=0;i&lt;=10;++i){\n        ctx.beginPath();\n        \/\/\u65b9\u6cd5\u5f00\u59cb\u4e00\u6761\u8def\u5f84\uff0c\u6216\u91cd\u7f6e\u5f53\u524d\u7684\u8def\u5f84\u3002\n        ctx.arc(150,150,150,0*Math.PI,0.2*i*Math.PI)\n        \/\/\u753b\u5706\n        ctx.stroke();\n        \/\/\u65b9\u6cd5\u4f1a\u5b9e\u9645\u5730\u7ed8\u5236\u51fa\u901a\u8fc7 moveTo() \u548c lineTo() \u65b9\u6cd5\u5b9a\u4e49\u7684\u8def\u5f84\u3002\u9ed8\u8ba4\u989c\u8272\u662f\u9ed1\u8272\u3002\n        await sleep(90);\n        \/\/\u5ef6\u8fdf\n    }\n    window.requestAnimationFrame(drow);\n    \/\/\u52a8\u753b\n}\nfunction init(){\n    window.requestAnimationFrame(drow);\n\n}\n\nwindow.onload = init<\/code><\/pre>\n\n\n\n<p>\u5176\u4e2d\u7684sleep\u51fd\u6570\u89e3\u91ca<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>const myFirstPromise = new Promise((resolve, reject) => {\n  \/\/ \u5f53\u5f02\u6b65\u64cd\u4f5c\u6210\u529f\u65f6\uff0c\u6211\u4eec\u8c03\u7528 resolve(...)\uff0c\u5f53\u5176\u5931\u8d25\u65f6\uff0c\u8c03\u7528 reject(...)\u3002\n  \/\/ \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u6211\u4eec\u4f7f\u7528 setTimeout(...) \u6765\u6a21\u62df\u5f02\u6b65\u4ee3\u7801\u3002\n  \/\/ \u5728\u5b9e\u9645\u60c5\u51b5\u4e2d\uff0c\u4f60\u53ef\u80fd\u4f1a\u4f7f\u7528\u7c7b\u4f3c XHR \u6216 HTML API \u7b49\u3002\n  setTimeout(() => {\n    resolve(\"\u6210\u529f\uff01\"); \/\/ \u8036\uff01\u4e00\u5207\u987a\u5229\uff01\n  }, 250);\n});\n\nmyFirstPromise.then((successMessage) => {\n  \/\/ successMessage \u662f\u6211\u4eec\u5728\u4e0a\u9762\u7684 resolve(...) \u51fd\u6570\u4e2d\u4f20\u5165\u7684\u4efb\u4f55\u5185\u5bb9\u3002\n  \/\/ \u5b83\u4e0d\u4e00\u5b9a\u662f\u5b57\u7b26\u4e32\uff0c\u4f46\u5982\u679c\u5b83\u53ea\u662f\u4e00\u4e2a\u6210\u529f\u7684\u6d88\u606f\uff0c\u90a3\u4e48\u5b83\u5927\u6982\u7387\u662f\u5b57\u7b26\u4e32\u3002\n  console.log(`\u8036\uff01${successMessage}`);\n});\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>https:\/\/www.w3school.com.cn\/tags\/html_ref_canvas.asp \u5faa\u73af [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":371,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-374","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-javascript"],"_links":{"self":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts\/374"}],"collection":[{"href":"\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=374"}],"version-history":[{"count":1,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/374\/revisions"}],"predecessor-version":[{"id":375,"href":"\/index.php?rest_route=\/wp\/v2\/posts\/374\/revisions\/375"}],"wp:featuredmedia":[{"embeddable":true,"href":"\/index.php?rest_route=\/wp\/v2\/media\/371"}],"wp:attachment":[{"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=374"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=374"},{"taxonomy":"post_tag","embeddable":true,"href":"\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=374"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}