CSS3 倒计时 / 技能冷却

小灰灰 2022-04-18 01:45 335阅读 0赞

![在这里插入图片描述][201811061829484.gif]

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf8">
    <style>
    :root {
    	--count-down-ring-size: 10em;
    	--count-down-ring-border: calc(var(--count-down-ring-size) / 2);
    	--count-down-ring-bg-color: lightgray;
    	--count-down-ring-fg-color: red;
    }
    .count-down-ring {
    	width: var(--count-down-ring-size);
    	height: var(--count-down-ring-size);
    	position: relative;
    }
    .count-down-left, .count-down-right {
    	width: 50%;
    	height: 100%;
    	position: absolute;
    	overflow: hidden;
    }
    .count-down-left, .count-down-left-ring {
    	left: 0;
    }
    .count-down-right, .count-down-right-ring {
    	/* 即使边框为0，两个div间还是会露出缝，因此 */
    	right: 1px;
    }
    .count-down-left-ring, .count-down-right-ring {
    	width: 200%;
    	height: 100%;
    	position: absolute;
    	border-width: var(--count-down-ring-border);
    	border-style: solid;
    	border-radius: 50%;
    	border-left-color: var(--count-down-ring-bg-color);
    	border-top-color: var(--count-down-ring-bg-color);
    	border-right-color: var(--count-down-ring-fg-color);
    	border-bottom-color: var(--count-down-ring-fg-color);
    	/* 这里必须采用border-box，把border限制在内部区域，否则会超出边界 */
    	box-sizing: border-box;
    }
    .count-down-left-ring {
    	transform: rotate(135deg);
    	animation: anim-count-down-left-ring 1s linear infinite;
    	display: block;
    }
    .count-down-right-ring {
    	transform: rotate(-45deg);
    	animation: anim-count-down-right-ring 1s linear infinite;
    	display: block;
    }
    @keyframes anim-count-down-left-ring {
    	from,50% {
    		transform: rotate(135deg);
    	}
    	/*50%, to {*/
    	to {
    		transform: rotate(-45deg);
    	}
    }
    @keyframes anim-count-down-right-ring {
    	/*from, 50% {*/
    	from {
    		transform: rotate(-45deg);
    	}
    	50%,to {
    		transform: rotate(-225deg);
    	}
    }
    .count-down-ring::after {
    	content: attr(data-content);
    	position: absolute;
    	top: 50%;
    	left: 50%;
    	transform: translate(-50%, -50%);
    	color: white;
    	font-size: calc(var(--count-down-ring-size) / 2);
    	font-weight: bold;
    }
    </style>
    <script>
    window.onload = ()=> {
    	const COUNTDOWN_MAX = 10;
    	let countdownValue = COUNTDOWN_MAX;
    	const countdowns = document.querySelectorAll(".count-down-ring");
    	const countdownId = setInterval(()=>{
    		countdownValue--;
    		if(countdownValue < 0) {
    			countdownValue = COUNTDOWN_MAX; 
    		}
    		countdowns.forEach((countdown)=>{
    			//data-*和class属性在javascript里面会有一层特殊处理，分别存储到dataset和classList对象中（注意单词拼写与大小写）
    			countdown.setAttribute("data-content", countdownValue);
    			//countdown.dataset.content = countdownValue;
    		});
    	}, 1000);
    };
    </script>
    </head>
    <body>
    <div class="count-down-ring" data-content="10">
    	<div class="count-down-left">
    		<div class="count-down-left-ring"></div>
    	</div>
    	<div class="count-down-right">
    		<div class="count-down-right-ring"></div>
    	</div>
    </div>
    <pre>
    	(1)当border-width较小的时候是圆环，当border-width较大的时候是整圆
    	(2)交换动画50%的位置(与from并列 或 与to并列)可以让动画的起始位置上下颠倒
    	
    	当然，它还可以贴上背景图片，做游戏中的技能冷却按钮
    </pre>
    </body>
    </html>

[201811061829484.gif]: /images/20220418/ceaaf04f5845448e86b2ed9d81a7c34e.png