HTML5在线教程之canvas仿写贝塞尔曲线的示例代码

HTML5在线教程之canvas仿写贝塞尔曲线的示例代码

本篇文章小编主要是和大家分享一下canvas仿写贝塞尔曲线的示例，文章中会有代码列出供大家详细了解。对HTML5感兴趣想要学好HTML5开发技术的小伙伴们随着小编一起来看一下吧。

代码如下：

html：

您的浏览器不支持canvas

css：

canvas{ border: 1px solid black;}

js：

var canvas = document.getElementById("mycanvas");

var context = canvas.getContext("2d");

var x1 = 100;

var y1 = 100;

var x2 = 400;

var y2 = 400;

draw();

function draw(){

//画半透明的线

context.beginPath();

context.moveTo(500,0);

context.lineTo(0,500);

context.strokeStyle = "rgba(0,0,0,0.3)";

context.lineWidth = 10;

context.stroke();

//画连接线

context.beginPath();

context.moveTo(0,500);

context.lineTo(x1,y1);

context.lineWidth = 2;

context.strokeStyle = "black";

context.stroke();

context.beginPath();

context.moveTo(500,0);

context.lineTo(x2,y2);

context.lineWidth = 2;

context.strokeStyle = "black";

context.stroke();

//画红球

context.beginPath();

context.arc(x1,y1,10,0,Math.PI*2);

context.fillStyle = "orange";

context.fill();

//画蓝球

context.beginPath();

context.arc(x2,y2,10,0,Math.PI*2);

context.fillStyle = "blue";

context.fill();

//画贝塞尔曲线

context.beginPath();

context.moveTo(0,500);

context.bezierCurveTo(x1,y1,x2,y2,500,0);

context.lineWidth = 5;

context.stroke();

}

//拖动小球做动画

//判断是否拖动小球

//如果在小球上就做动画

canvas.onmousedown = function(e){

var ev = e || window.event;

var x = ev.offsetX;

var y = ev.offsetY;

//判断是否在红球上

var dis = Math.pow((x-x1),2) + Math.pow((y-y1),2);

if(dis<100){

console.log("鼠标在红球上");

canvas.onmousemove = function(e){

var ev = e || window.event;

var xx = ev.offsetX;

var yy = ev.offsetY;

//清除画布

context.clearRect(0,0,canvas.width,canvas.height);

x1 = xx;

y1 = yy;

//重绘制

draw();

}

}

//判断鼠标是否在蓝球上

var dis = Math.pow((x-x2),2) + Math.pow((y-y2),2);

if(dis<100){

canvas.onmousemove = function(e){

var ev = e || window.event;

var xx1 = ev.offsetX;

var yy1 = ev.offsetY;

//清除画布

context.clearRect(0,0,canvas.width,canvas.height);

x2 = xx1;

y2 = yy1;

//重绘制

draw();

}

}

}

document.onmouseup =function(){

canvas.onmousemove = " ";

}

以上就是小编给大家分享的canvas仿写贝塞尔曲线的示例代码，希望对小伙伴们有所帮助。