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[网页设计]html5 canvas多个图像旋转


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html ="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小白童鞋;你的支持是我最大的快乐!!</canvas></body></html>