<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>多个图像围绕中心点旋转</title>
<script src="js/modernizr.js"></script>
</head> <body>
<script type="text/javascript">
window.addEventListener('load',eventWindowLoaded,false);
function eventWindowLoaded(){
canvasApp();
}
function canvasSupport(){
return Modernizr.canvas;
}
function canvasApp(){
if(!canvasSupport()){
return;
}else{
var theCanvas = document.getElementById('canvas')
var context = theCanvas.getContext("2d") }
drawScreen();
function drawScreen(){ context.setTransform(1,0,0,1,0,0);
var angleInRadians = 45 * Math.PI / 180;
var x = 50;
var y = 100;
var width = 40;
var height = 40;
context.translate(x+.5*width,y+.5*height);
context.rotate(angleInRadians);
context.fillStyle="red";
context.fillRect(-.5*width,-.5*height,width,height);
context.setTransform(1,0,0,1,0,0);
var angleInRadians = 75 * Math.PI / 180;
var x = 100;
var y = 100;
var width = 40;
var height = 40;
context.translate(x+.5*width,y+.5*height);
context.rotate(angleInRadians);
context.fillStyle="red";
context.fillRect(-.5*width,-.5*height,width,height);
context.setTransform(1,0,0,1,0,0);
var angleInRadians = 90 * Math.PI / 180;
var x = 150;
var y = 100;
var width = 40;
var height = 40;
context.translate(x+.5*width,y+.5*height);
context.rotate(angleInRadians);
context.fillStyle="red";
context.fillRect(-.5*width,-.5*height,width,height);
context.setTransform(1,0,0,1,0,0);
var angleInRadians = 120 * Math.PI / 180;
var x = 200;
var y = 100;
var width = 40;
var height = 40;
context.translate(x+.5*width,y+.5*height);
context.rotate(angleInRadians);
context.fillStyle="red";
context.fillRect(-.5*width,-.5*height,width,height); } } </script>
<canvas id="canvas" width="500" height="500">
你的浏览器无法使用canvas
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</canvas>
</body>
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