<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body onload="draw(),drawarc()">
<!--绘制的步骤：获取canvas元素->取得上下文->填充与绘制边框->设定绘图样式-->
<!--绘制其他复杂图形需要使用路径：开始创建路径->创建图形路径->关闭路径->绘制图形-->
<!--eg:绘制矩形-->
绘制矩形:<canvas id="ca"></canvas><br />
绘制圆形：<canvas id="yuan"></canvas>
</body>
</html>
<script>
//绘制矩形
function draw(){
var canvas=document.getElementById('ca'); //获取canvas元素
if (canvas==null)
return false;
var context=canvas.getContext('2d'); //取得上下文
context.fillStyle='#EEEFF'; //填充颜色
context.fillRect(0,0,400,300); //填充矩形 (矩形1)
context.fillStyle='red';
context.strokeStyle='blue'; //边框颜色
context.lineWidth=1; //边框宽度
context.fillRect(50,50,100,100); //填充矩形（内部矩形2）
context.strokeRect(50,50,100,100); //绘制边框
}
//绘制圆形
function drawarc(){
var canvas2=document.getElementById('yuan'); //获取canvas元素
if (canvas2==null)
if(canvas2==null)
return false;
var context2=canvas2.getContext('2d'); //取得上下文
context2.fillStyle='#EEEEEF';
context2.fillRect(0,0,400,300);
var n=0;
context2.beginPath(); //开始创建路径
context2.arc(50,50,15,0,Math.PI*2,true); //创建圆形路径
context2.closePath(); //关闭路径
context2.fillStyle='Rgba(255,0,0,0.25)'; //设置颜色
context2.fill(); //填充图形
// for(var i=0;i<10;i++){
// context2.beginPath(); //开始创建路径
// context2.arc(i*25,i*25,i*10,0,Math.PI*2,true); //创建圆形路径
// context2.closePath(); //关闭路径
// context2.fillStyle='Rgba(255,0,0,0.25)'; //设置颜色
// context2.fill(); //填充图形
// }
}
</script>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>实验2-音视频</title>
</head>
<body>
<video width="320" height="240" controls="controls">
<source src="https://www.w3school.com.cn/i/movie.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>
<audio src="https://www.w3school.com.cn/i/song.ogg" controls="controls">
Your browser does not support the audio element.
</audio>
</body>
</html>
