怎样设置线条的末端样式

需要使用: ctx.lineCap 属性. 直译过来就是 "线条的帽子". 它有三个属性值:

1. butt: 末端为方形

2. round: 末端为原形

3. square: 末端为方形, 但会多出一个宽度相同, 高度为宽度一半的方形延伸.

下面是实际演示:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>

<body>
    <canvas id="canv" width="300" height="300"></canvas>
    <script>
        function draw(){
            var canvas = document.getElementById("canv");
            if (!canvas.getContext) return;
            var ctx = canvas.getContext("2d");

            ctx.beginPath();
            ctx.moveTo(50, 50);
            ctx.lineTo(50, 150);
            ctx.lineWidth = 12;
            ctx.lineCap = "butt";
            ctx.stroke();

            ctx.beginPath();
            ctx.moveTo(80, 50);
            ctx.lineTo(80, 150);
            ctx.lineWidth = 12;
            ctx.lineCap = "round";
            ctx.stroke();

            ctx.beginPath();
            ctx.moveTo(120, 50);
            ctx.lineTo(120, 150);
            ctx.lineWidth = 12;
            ctx.lineCap = "square";
            ctx.stroke();
        }
        draw();
    </script>
</body>

</html>