a example for rorating the image

rotateImage = function(p, angle, whence){
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.angle = p.angle;
canvas.angle = canvas.angle < 0 ? 360 + canvas.angle :canvas.angle
p.parentNode.replaceChild(canvas, p);
};