HTML5的canvas标签用于绘制图像(通过脚本,通常是 JavaScript)。不过,canvas元素本身并没有绘制能力(它仅仅是图形的容器)必须使用脚本来完成实际的绘图任务。
狼蚁网站SEO优化,具体了一下使用画布canvas的步骤
画布
canvas
在页面上规划出一块空间,canvas标签,通过javascript控制画布完成绘制
1.获取画布
var canvas=document.getElementById("");
2.获取上下文对象 (获取画笔)
var cx=canvas.getContext(“2d”);
3.设置画笔样式
cx.fillStyle=‘red';
cx.strokeStyle=‘blue';
4.开始绘制
狼蚁网站SEO优化是对于canvas使用,绘制一个简单钟表的小例子
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<script>
window.onload=function(){
//1.获取画布
var canvas=document.getElementById("canvas");
//2.获取画笔
var cx=canvas.getContext("2d");
function clock(){
//3.设置画笔样式
cx.fillStyle="orange";
//4.绘制图形
//绘制表盘
cx.beginPath();
cx.arc(300,300,200,0,Math.PI2)
cx.closePath();
cx.fill();
//绘制时刻度
cx.lineWidth=2;
cx.strokeStyle="black";
for(var i=0;i<12;i++){
cx.save();
cx.translate(300,300);
cx.rotate(i(Math.PI/6));
// cx.beginPath();
cx.moveTo(0,-180);
cx.lineTo(0,-200);
// cx.closePath();
cx.stroke();
cx.fillStyle="black";
cx.font="16px blod";
cx.rotate(Math.PI/6)
cx.fillText(i+1,-5,-220);
cx.restore();
}
//绘制分刻度
for(var i=0;i<60;i++){
cx.save();
cx.translate(300,300);
cx.rotate(i(Math.PI/30));
cx.beginPath();
cx.moveTo(0,-190);
cx.lineTo(0,-200);
cx.closePath();
cx.stroke();
cx.restore();
}
//获取当前时间
var today=new Date();
var hour=today.getHours();
var min=today.getMinutes();
var sec=today.getSeconds();
hour=hour+min/60;
//绘制时针
cx.lineWidth=5;
cx.save();
cx.beginPath();
cx.translate(300,300);
cx.rotate(hour(Math.PI/6));
cx.moveTo(0,10);
cx.lineTo(0,-100);
cx.closePath();
cx.stroke();
cx.restore();
//绘制分针
cx.lineWidth=3;
cx.save();
cx.beginPath();
cx.translate(300,300);
cx.rotate(min(Math.PI/30));
cx.moveTo(0,10);
cx.lineTo(0,-120);
cx.closePath();
cx.stroke();
cx.restore();
//绘制秒针
cx.lineWidth=1;
cx.strokeStyle="red";
cx.save();
cx.beginPath();
cx.translate(300,300);
cx.rotate(sec(Math.PI/30));
cx.moveTo(0,10);
cx.lineTo(0,-160);
cx.closePath();
cx.stroke();
cx.restore();
//绘制交叉处
cx.fillStyle="#c";
cx.strokeStyle="red";
cx.save();
cx.translate(300,300);
cx.beginPath();
cx.arc(0,0,5,0,Math.PI2);
cx.closePath();
cx.fill();
cx.stroke();
cx.restore();
setTimeout(clock,1000);
}
clock()
}
</script>
</head>
<body>
<canvas id="canvas" width="600px" height="600px" style="background-color: #c;"></canvas>
</body>
</html>
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持狼蚁SEO。