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js图片旋转
<script type="text/javascript" language="javascript"> function rotate(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; } //alert(canvas.width) 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); } //向右旋转 function rotateRight(id, angle) { rotate(id, angle == undefined ? 90 : angle); } //向左旋转 function rotateLeft(id, angle) { rotate(id, angle == undefined ? -90 : -angle); } </script>
调用方法:
<div class="content"> <div class="data"> <a href="javascript:void(0)" style="font-weight: bold; text-decoration: none; font-size: 16px;" onclick="rotateRight(‘theimage‘,90);">右转</a>
<a href="javascript:void(0)" style="font-weight: bold; font-size: 16px; text-decoration: none;"
onclick="rotateLeft(‘theimage‘,90);">左转</a><br>
<img src="a.jpg" id="theimage" onl oad="resizeimg(this,this.width,this.height)" width="100%" alt="800×1422" style="cursor: pointer;" /> </a> <div style="clear: both"> </div> </div> </div>
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