<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
canvas{
border: 1px solid #CCC;
background-color: rgb(252,254,251);
}
</style>
</head>
<body>
<canvas width="500" height="500"></canvas>
<script>
var mcanvas = document.querySelector("canvas");//获取页面元素
var ctx = mcanvas.getContext("2d");//
var mimg = new Image();
mimg.src = "../image/2345.jpg";
mimg.onload = function () {
//要先设置在获取 前人栽树后人乘凉 ，加载问题
var imgw = mimg.width;
var imgh = mimg.height;//获取长度及宽度
ctx.translate(250,250);//坐标系发生位移
console.log(imgh);
//未获取的元素
function draw() {
//绘制前先清除
ctx.clearRect(-500,-500,1000,1500);//清除该坐标系上的矩形
ctx.drawImage(mimg,0-(imgw/2),0-(imgh/2));
ctx.rotate(Math.PI/180*5);//坐标系旋转带动图形发生旋转
//
}
setInterval(draw,100);
}
</script>
</body>
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