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Introduction to examples of drawing circles on canvas in HTML5

黄舟Original: 2017-07-22 09:56:492327browse

Use arc in canvas to draw circular patterns. The function prototype is: context.arc(x, y, radius, start angle, end angle, whether to rotate counterclockwise); so you can draw an arc by modifying the start angle and end angle.

The code is as follows:

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>html5圆形</title>
	<script type="text/javascript">
		window.addEventListener("load",function(){
			//canvas的2d上下文
			var ctx=document.getElementById("canvas").getContext("2d");
			//圆1
			ctx.beginPath();
			ctx.arc(150,45,35,0,Math.PI*2,false);
			ctx.fillStyle="rgba(192,80,77,0.7)";//半透明的红色
			ctx.fill();
			ctx.strokeStyle="rgba(192,80,77,1)";//红色
			ctx.stroke();
			//圆2
			ctx.beginPath();
			ctx.arc(125,95,35,0,Math.PI*2,false);
			ctx.fillStyle="rgba(155,187,89,0.7)";//半透明绿色
			ctx.fill();
			ctx.strokeStyle="rgba(155,187,89,1)";//绿色
			ctx.stroke();
			//圆3
			ctx.beginPath();
			ctx.arc(175,95,35,Math.PI*2,false);
			ctx.fillStyle="rgba(128,100,162,0.7)";//半透明的紫色
			ctx.fill();
			ctx.strokeStyle="rgba(128,100,132,1)";//紫色
			ctx.stroke();
		});
	</script>
</head>
<body>

	<canvas id="canvas" width="600" height="600"></canvas>
</body>
</html>

The picture above shows three circles drawn tossing each other. In addition, you can directly modify the starting angle and ending arc to draw an arc.

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