在canvas中插入图片，当点击右箭头时，图片顺时针旋转90°，但是点击时没有效果，到底哪里错了，请各位老师指教，非常谢谢！
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
无标题文档 body{ background:black; } window.onload = function() { var aInput = document.getElementsByName("input"); var oImg = document.getElementById("img1"); var yImg = new Image(); var iNow = 0; yImg.onload = function() { draw(oImg); } yImg.src = oImg.src; function draw(obj) { var oC = document.createElement("canvas"); var oGC = oC.getContext('2d'); oC.width = obj.width; oC.height = obj.height; obj.parentNode.replaceChild(oC,obj); oGC.drawImage(obj,0,0); aInput[1].onclick = function() { iNow++; toChange(); } function toChange() { switch(iNow) { case 1: oC.width = obj.height; oC.height = obj.width; oGC.rotate(90*Math.PI/180); oGC.drawImage(obj,0,-obj.height); break; } } } }
