quadraticCurveTo（路徑命令）

Created: November-22, 2018

context.quadraticCurveTo(controlX, controlY, endingX, endingY)

繪製從當前筆位置開始到給定結束座標的二次曲線。另一個給定的控制座標確定曲線的形狀（曲率）。

StackOverflow 文件

<!doctype html>
<html>
<head>
<style>
    body{ background-color:white; }
    #canvas{border:1px solid red; }
</style>
<script>
window.onload=(function(){

    // get a reference to the canvas element and it's context
    var canvas=document.getElementById("canvas");
    var ctx=canvas.getContext("2d");

    // arguments
    var startX=25;
    var startY=70;
    var controlX=75;
    var controlY=25;
    var endX=125;
    var endY=70;

    // A quadratic curve drawn using "moveTo" and "quadraticCurveTo" commands
    ctx.beginPath();
    ctx.moveTo(startX,startY);
    ctx.quadraticCurveTo(controlX,controlY,endX,endY);
    ctx.stroke();

}); // end window.onload
</script>
</head>
<body>
    <canvas id="canvas" width=200 height=150></canvas>
</body>
</html>