H5实现绘制三角形并在其三个顶点画三个圆添加点击事件

1.效果如下：

代码如下：

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
    </head>
    <body>
        <canvas id="canvas"></canvas>
    </body>
    <script type="text/javascript">
        //获取canvas容器
        var can = document.getElementById('canvas');
        //创建一个画布
        var ctx = can.getContext('2d');
        //绘制三角形(x1,x2)、(x2,y2) (x3,y3)表示三角形三个点坐标,color表示颜色,type表示绘制类型(填充fill和不填充stroke)
        var draw = function(x1, y1, x2, y2, x3, y3, color, type) {
            ctx.beginPath();
            ctx.moveTo(x1, y1);
            ctx.lineTo(x2, y2);
            ctx.lineTo(x3, y3);
            ctx[type + 'Style'] = color;
            ctx.closePath();
            ctx[type]();
        }
        draw(100,100,175,20,280,100,'green','stroke')
        //绘制圆形(x,y)圆心坐标,r表示半径,start表示起始角度,end表示结束角度,color表示颜色,type表示绘制类型(填充fill和不填充stroke)
        var draw = function(x, y, r, start, end, color, type) {
            var unit = Math.PI / 180;
            ctx.beginPath();
            ctx.arc(x, y, r, start * unit, end * unit);
            ctx[type + 'Style'] = color;
            ctx.closePath();
            ctx[type]();
        }
        draw(175,20,20,0,360,'yellow','fill')
        
        var draw = function(x, y, r, start, end, color, type) {
            var unit = Math.PI / 180;
            ctx.beginPath();
            ctx.arc(x, y, r, start * unit, end * unit);
            ctx[type + 'Style'] = color;
            ctx.closePath();
            ctx[type]();
        }
        draw(100,100,20,0,360,'yellow','fill')
        
        var draw = function(x, y, r, start, end, color, type) {
            var unit = Math.PI / 180;
            ctx.beginPath();
            ctx.arc(x, y, r, start * unit, end * unit);
            ctx[type + 'Style'] = color;
            ctx.closePath();
            ctx[type]();
        }
        draw(280,100,20,0,360,'yellow','fill')
        
        can.onclick=function(e){
            //获取鼠标位置
            var x=e.clientX-can.offsetLeft;
            var y=e.clientY-can.offsetTop;
            //通过圆心判断鼠标是否在圆的范围内
            if(x>=80&&x<=120&&y>=80&&y<=120)
            {
                window.open('https://www.baidu.com');
            }
        }
    </script>
</html>

2.补充：用border画三角形，其效果如下：

代码如下：

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title></title>
    </head>
    <style>
        .circle {
            width: 50px;
            height: 50px;
            border-radius: 150px;
            position: absolute;
            left: 230px;
            top:80px;
            background: yellow;
        }

        .circle1 {
            width: 50px;
            height: 50px;
            border-radius: 150px;
            position: absolute;
            left: 180px;
            top:220px;
            background: yellow;
        }

        .circle2 {
            width: 50px;
            height: 50px;
            border-radius: 150px;
            position: absolute;
            left: 380px;
            top:220px;
            background: yellow;
            
        }

        .triangle {
            width: 0;
            height: 0;
            border-bottom: 150px solid red;
            border-right: 150px solid transparent;
            border-left: 50px solid transparent;
            margin-left: 200px;
            margin-top: 100px;
        }
    </style>
    <body>
        <div class="triangle">
        <div class="circle"></div>
        <div class="circle1"></div>
        <div class="circle2"></div>
        </div>
    </body>
</html>

原文地址：https://www.cnblogs.com/Hero-Bin/p/11865892.html