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Example of using css3 to create a ring progress bar

高洛峰Original: 2017-03-17 11:41:071549browse

This article shares an example of using css3 to create a ring progress bar

Recently, a PC-side project has to create a page like this. Everything else is very simple. The key is the percentage ring effect. My initial plan was to use canvas to implement it directly, because it is very simple to implement a circle on canvas.

The code for the canvas implementation of the circle is posted below. If you need it, you can try it, because today I mainly talk about the CSS3 method, and I won’t explain more about the canvas

<!DOCTYPE html>  
<html>  
<head>  
    <meta charset="UTF-8">  
    <title></title>  
</head>  
<body>  
    <canvas id="canvas" width="200" height="200"></canvas>  
    <script>  
            var canvas = document.getElementById(&#39;canvas&#39;);  
            var process = 0;  
            var context = canvas.getContext(&#39;2d&#39;);  
  
            // 画外圆  
            context.beginPath();  
            context.arc(100, 100, 80, 0, Math.PI*2);  
            context.closePath();  
            context.fillStyle = &#39;#666&#39;;  
            context.fill();  
  			drawCricle(context, process);
            
            function drawCricle(ctx, percent){  
                // 进度环  
                ctx.beginPath();  
                ctx.moveTo(100, 100);    
                ctx.arc(100, 100, 80, Math.PI * 1.5, Math.PI * (1.5 + 2 * percent / 100 ));  
                ctx.closePath();  
                ctx.fillStyle = &#39;red&#39;;  
                ctx.fill();  
  
                // 内圆
                ctx.beginPath();  
                ctx.arc(100, 100, 75, 0, Math.PI * 2);  
                ctx.closePath();  
                ctx.fillStyle = &#39;white&#39;;  
                ctx.fill();  
  
                // 填充文字  
                ctx.font= "bold 30px microsoft yahei";   
                ctx.fillStyle = "black";  
                ctx.textAlign = "center";    
                ctx.textBaseline = &#39;middle&#39;;    
                ctx.moveTo(100, 100);    
                ctx.fillText(process + &#39;%&#39;, 100, 100);  
            }  
   
    </script>  
</body>  
</html>

The reason why I didn’t use canvas to implement it was because the product told me that there would be a lot of tasks in the future. I asked if there would be more than 99 tasks? He said it was possible, and you could set the upper limit at 999.

If 999 canvas rings are used to render. . . Hundreds of them are enough, so I have no choice but to use css3, at least it will be much faster. But it seems that there is no way to directly draw a progress ring in CSS.

I will post the complete code later, but here is the general structure.

To achieve the style of progress bar using css, the only way we can think of seems to be to use circles of different sizes to overlap. If you want the loading effect of the animation constantly rotating, that would be too much. If it were simple, I would be very happy, but it's a pity. .

First we need to create a background circle, like this

Example of using css3 to create a ring progress bar

Then we need to create an inner circle to mask

Example of using css3 to create a ring progress bar

It looks a bit like it, then our next focus is how to make it change with the percentage such as dynamic display. js is necessary, let me talk about the style first

Next step we need to create two semicircles, like this

Example of using css3 to create a ring progress bar

css to achieve semicircle There are many methods, you can use Baidu by yourself. I use clip:rect(); this method to cut into a semicircle. After doing this, we only need to use js to control the rotation angle of the left and right semicircles rotate(). .

Example of using css3 to create a ring progress bar

Remember to unify the colors of the left and right semicircles at the end, I will post it below Source code, you can introduce a jq and use it directly

Example of using css3 to create a ring progress bar

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			.circle {
				width: 200px;
				height: 200px;
				position: relative;
				border-radius: 50%;
				background: red;
			}
				
			.clip_left,.clip_right{
				width:200px;
				height:200px;
				position: absolute;
				top: 0px;left: 0px;
			}
			.circle_left, .circle_right{
				width:200px;
				height:200px;
				position: absolute;
				border-radius: 50%;
				top: 0px;left: 0px;
				background: green;
			}
			/*出于展示用的改变背景色*/
			/*.circle_left{
				background: green;
			}
			.circle_right{
				background: lightblue;
			}*/
			.circle_right,.clip_right {
				clip:rect(0,auto,auto,100px);
			}
			.circle_left , .clip_left{
				clip:rect(0,100px,auto,0);
			}
				
			/*
			*当top和left取值为auto时，相当于0
			*当bottom和right取值为auto时，相当于100%
			*/
			.mask {
				width: 150px;
				height: 150px;
				border-radius: 50%;
				left: 25px;
				top: 25px;
				background: #FFF;
				position: absolute;
				text-align: center;
				line-height: 150px;
				font-size: 16px;
			}

		</style>
	</head>
	<body>
		<!--背景圆-->
		<p class="circle">
			<!--左半边圆-->
			<p class="circle_left">
				<p class="clip_left">
					
				</p>
			</p>
			<!--右半边圆-->
			<p class="circle_right">
				<p class="clip_right"></p>
			</p>
			<p class="mask">
				<span>10</span>%
			</p>
		</p>
		<script src="../jquery-2.2.3.min.js"></script>
		<script>
			$(function(){
				if( $(&#39;.mask span&#39;).text() <= 50 ){
					$(&#39;.circle_right&#39;).css(&#39;transform&#39;,&#39;rotate(&#39;+($(&#39;.mask span&#39;).text()*3.6)+&#39;deg)&#39;);
				}else{
					$(&#39;.circle_right&#39;).css({
						&#39;transform&#39;:&#39;rotate(0deg)&#39;,
						"background":"red"
					});
					$(&#39;.circle_left&#39;).css(&#39;transform&#39;,&#39;rotate(&#39;+(($(&#39;.mask span&#39;).text()-50)*3.6)+&#39;deg)&#39;);
				}
			})
		</script>
	</body>
</html>

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