html5画布旋转效果示例_html5教程技巧

/*
* 功能：画布旋转
*/
(function(){
var canvas=null,
context=null,
angle=0;
function resetCanvas(){
canvas=document.getElementById("jb51");
canvas.width=window.innerWidth;
canvas.height=window.innerHeight;
context=canvas.getContext("2d");
}
function animate(){
context.save();
try{
//清除画布
context.clearRect(0, 0, canvas.width, canvas.height);
//设置原点
context.translate(canvas.width * 0.5, canvas.height * 0.5);
//旋转角度
context.rotate(angle);
//设置填充颜色
context.fillStyle = "#FF0000";
//绘制矩形
context.fillRect(-30, -30, 60, 60);
angle += 0.05 * Math.PI;
}
finally{
context.restore();
}
}
$(window).bind("resize",resetCanvas).bind("reorient",resetCanvas);
$(document).ready(function(){
window.scrollTo(0,1);
resetCanvas();
setInterval(animate,40);
});
})();