html5 canvas结构基础 

<!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>小白童鞋的canvas之基本配置篇</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.fillStyle="#ff0000";
	  context.fillRect(0,0,400,400);
	  context.fillStyle="#000000";
	  context.font="20px _sans";
	  context.textBaseline="top";
	  context.fillText("如有疑问加QQ：1035417613;小白童鞋",0,0);
        }
}


</script>
<canvas id="canvas" width="500" height="500">
你的浏览器无法使用canvas
如有疑问加QQ：1035417613;小白童鞋；你的支持是我最大的快乐！！
</canvas>
</body>
</html>

 https://files.cnblogs.com/files/LoveOrHate/canvas1-1.rar（DEMO下载）

   window.addEventListener('load',eventWindowLoaded,false);

脚本执行的过程中需要第一个监听load对象

在html页面加载结束时发生

事件load

事件处理器函数eventWindowLoaded

theCanvas.getContext("2d"）获取2d上下文

 

modernizr.js是个不错的东西可以检测支持情况
我是在这里下的（吐槽一下链接有点长）
modernizr.com/download/#-fontface-backgroundsize-borderimage-borderradius-boxshadow-flexbox-hsla-multiplebgs-opacity-rgba-textshadow-cssanimations-csscolumns-generatedcontent-cssgradients-cssreflections-csstransforms-csstransforms3d-csstransitions-applicationcache-canvas-canvastext-draganddrop-hashchange-history-audio-video-indexeddb-input-inputtypes-localstorage-postmessage-sessionstorage-websockets-websqldatabase-webworkers-geolocation-inlinesvg-smil-svg-svgclippaths-touch-webgl-shiv-cssclasses-addtest-prefixed-teststyles-testprop-testallprops-hasevent-prefixes-domprefixes-load



posted @ 2015-04-02 20:48  一点点白  阅读(656)  评论(0)  编辑  收藏  举报