js 实现图片的旋转 结合css3的属性transform

Question

我想在IE9下实现点击按钮进行图片的翻转，之前使用了滤镜，但有一个问题，图片在旋转时不是以图片中心为定点进行旋转，在网上查了css3的一个属性transform 可以实现以中心点进行旋转，但试了好多，都没实现，下面是滤镜实现代码：
/**
* 图片旋转
* @param id 图片id
* @param angle 旋转度数
* @param whence 旋转方向、从何处开始旋转
*/
rotate : function(id,angle,whence) {
var p = document.getElementById(id);
if (!whence) {
p.angle = ((p.angle==undefined?0:p.angle) + angle) % 360;
} else {
p.angle = angle;
}

    if (p.angle >= 0) {
        var rotation = Math.PI * p.angle / 180;
    } else {
        var rotation = Math.PI * (360+p.angle) / 180;
    }
    var costheta = Math.cos(rotation);
    var sintheta = Math.sin(rotation);

    if (document.all && !window.opera) {
        var canvas = document.createElement('img');

        canvas.src = p.src;
        canvas.height = p.height;
        canvas.width = p.width;

        canvas.style.filter = "progid:DXImageTransform.Microsoft.Matrix(M11="+costheta+",M12="+(-sintheta)+",M21="+sintheta+",M22="+costheta+",SizingMethod='auto expand')";
    } else {
        var canvas = document.createElement('canvas');
        if (!p.oImage) {
            canvas.oImage = new Image();
            canvas.oImage.src = p.src;
        } else {
            canvas.oImage = p.oImage;
        }

        canvas.style.width = canvas.width = Math.abs(costheta*canvas.oImage.width) + Math.abs(sintheta*canvas.oImage.height);
        canvas.style.height = canvas.height = Math.abs(costheta*canvas.oImage.height) + Math.abs(sintheta*canvas.oImage.width);

        var context = canvas.getContext('2d');
        context.save();
        if (rotation <= Math.PI/2) {
            context.translate(sintheta*canvas.oImage.height,0);
        } else if (rotation <= Math.PI) {
            context.translate(canvas.width,-costheta*canvas.oImage.height);
        } else if (rotation <= 1.5*Math.PI) {
            context.translate(-costheta*canvas.oImage.width,canvas.height);
        } else {
            context.translate(0,-sintheta*canvas.oImage.width);
        }
        context.rotate(rotation);
        context.drawImage(canvas.oImage, 0, 0, canvas.oImage.width, canvas.oImage.height);
        context.restore();
    }
    canvas.id = p.id;
    canvas.onmousewheel = p.onmousewheel;
    canvas.angle = p.angle;
    p.parentNode.replaceChild(canvas, p);
},
    ------------------------------------------------------------
    在css样式中：
    #imgDiv{
            -ms-transform:rotate(90deg); /* IE 9 */
    }
    这样可以实现旋转，
    但我想使用js进行动态左右旋转，求大神们赐教！谢谢

Answer 1

jquery.rotate.js