任意旋转图片的js实例- zdz8207 - JavaEye技术网站企业库|免费b2b网站

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>任意旋转图片</title>
<script type="text/javascript" src="coos.ui.rotate.js"></script>
</head>
<body>
	<div id="inner"><img id="theimage" border="0" src="logo.jpg" /></div>
	<div style="position:absolute;top:235px;height:40px;">
		<input type="button" value="<-Rotate逆时针" name="RotateL" id="RotateL" onclick="rotateRight('theimage',90);">
		<input type="button" value="顺时针Rotate->" name="RotateR" id="RotateR" onclick="rotateLeft('theimage',90);">
		<input type="button" value="顺时针270" name="RotateR" id="RotateR" onclick="rotateLeft('theimage',270);">
	</div>
</body>
</html>

function rotate(id,angle,whence) {
	var p = document.getElementById(id);

	// 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.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;
	p.parentNode.replaceChild(canvas, p);
}

function rotateRight(id,angle) {
	rotate(id,angle==undefined?90:angle);
}

function rotateLeft(id,angle) {
	rotate(id,angle==undefined?-90:-angle);
}