Let the picture rotate to any angle and introduce the use of JQuery plug-in_jquery

Introduce the jquery.rotate.js file below, and then use $("selector").rotate(angle); to rotate to any angle,
for example $("#rotate-image").rotate(45); This sentence is placed in $(document).ready(function(){ });
to rotate the image with the ID rotate-image by 45 degrees.

However, it seems that it is always not displayed in Chrome.
Alas, after searching for two hours, I found out that Chrome is too tricky to get the length and width of the image.
The solution is to put $("#rotate-image").rotate(45); in
$(window).load(function(){ }); because in Chrome the image is When the statement in $(document).ready(function(){ }); is executed, the image is not loaded, which is a scam.

In addition, it is more convenient to rotate 90 degrees to the right and 90 degrees to the left by calling $("selector").rotateRight() and $("selector").rotateLeft().

jquery.rotate.js:

Copy code The code is as follows:

jQuery.fn.rotate = function(angle,whence) {
var p = this.get(0);
// we store the angle inside the image tag for persistence
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.round(Math.cos(rotation) * 1000) / 1000;
var sintheta = Math.round(Math.sin(rotation) * 1000) / 1000;
//alert(costheta "," sintheta);
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;
p.parentNode.replaceChild(canvas, p);
}
jQuery.fn.rotateRight = function(angle ) {
this.rotate(angle==undefined?90:angle);
}
jQuery.fn.rotateLeft = function(angle) {
this.rotate(angle==undefined?- 90:-angle);
}