简单描述：页面上有四个点，鼠标拖动四个点的位置来改变贝塞尔曲线的形状，双击放置点位
效果图：
代码：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> html{overflow: hidden;} * {padding: 0;margin: 0;} #box {background-color: #000000;} .point { width: 20px; height: 20px; background-color: #fff; border-radius: 50%; position: absolute; left: 100px; top:200px; text-align: center; line-height: 20px; } </style> </head> <body> <canvas></canvas> <div>b</div> <div>e</div> <div>1</div> <div>2</div> <script src="https://www.jb51.net/js/max.js"></script> </body> </html>
js：
/** * Created by Administrator on 2017/8/11. * js/max.js */ (function () { var curEle = null; var startPointView = document.querySelector(".startPoint"); var endPointPointView = document.querySelector(".endPoint"); var point1View = document.querySelector(".point1"); var point2View = document.querySelector(".point2"); var context = null; function init() { var canvasEle = document.querySelector("#box"); canvasEle.width = innerWidth; canvasEle.height = innerHeight; //实时监听网页大小 window.onresize = function () { canvasEle.width = innerWidth; canvasEle.height = innerHeight; }; context = canvasEle.getContext("2d"); context.strokeStyle = "white"; context.lineWidth = 10; //贝塞尔曲线简单用法 context.beginPath(); context.moveTo(300,300); context.bezierCurveTo(500,200,600,250,600,600); context.stroke(); //循环获取四个点的数组 for(var i=0;i<4;i++){ addEvent([startPointView,endPointPointView,point1View,point2View][i]); } //鼠标双击移除鼠标滑动事件 放下拖动的点 document.ondblclick = function () { document.removeEventListener("mousemove",move); }; } //鼠标按下拖动 function addEvent(ele) { ele.onmousedown = function () { curEle = this; document.addEventListener("mousemove",move); }; } //获取拖动位置并绘制贝塞尔曲线 function move(event) { curEle.style.left = event.pageX+"px"; curEle.style.top = event.pageY+"px"; context.clearRect(0,0,innerWidth,innerHeight); context.beginPath(); context.moveTo(getLeft(startPointView),getTop(startPointView)); context.bezierCurveTo(getLeft(point1View),getTop(point1View),getLeft(point2View),getTop(point2View),getLeft(endPointPointView),getTop(endPointPointView)); context.stroke(); } function getLeft(ele) { return parseInt(ele.style.left); } function getTop(ele) { return parseInt(ele.style.top); } init(); })();