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js實現圖片旋轉的三種方法
這篇文章主要介紹了js實現圖片旋轉的三種方法,需要的朋友可以參考下
1 使用jQueryRotate.js實現 示例代碼： 代碼如下: <!DOCTYPE html> <html> <head> <title></title> <style type="text/css"> #div1 { width: 800px; height: 600px; background-color: #ff0; position: absolute; } .imgRotate { width: 100px; height: 80px; position: absolute; top: 50%; left: 50%; margin: -40px 0 0 -50px; } </style> </head> <body> <div id="div1"> <img id="img1" class="imgRotate" src="http://www.baidu.com/img/logo-yy.gif" /> <input id="input2" type="button" value="btn2"></input> </div> </body> <script type="text/javascript" src="jquery.min.js"></script> <script type="text/javascript" src="jQueryRotate.js"></script> <script type="text/javascript"> var num = 0; $("#input2").click(function(){ num ++; $("#img1").rotate(90*num); }); </script> </html> 測試結果：chrome下效果正常，旋轉後img對象仍為img對象；ie8下效果正常，但旋轉後img對象變為下面對象，由於對象變化，若旋轉後仍按原來方法獲取img對象，則會報js錯誤。欲獲取image對象，可根據class獲取。如果圖像旋轉後，不進行其它操作，則可用此方法。若進行其它操作，如放大、縮小圖像，則此方法實現較復雜。 代碼如下: <span ...> <rvml:group class="rvml"...> <rvml:image class="rvml".../> </rvml:group> </span> 2 使用Microsoft提供的Matrix對象 示例代碼： 代碼如下: <!DOCTYPE html> <html> <head> <title></title> <style type="text/css"> #div1 { width: 800px; height: 600px; background-color: #ff0; position: absolute; } .imgRotate { width: 100px; height: 100px; position: absolute; top: 50%; left: 50%; margin: -50px 0 0 -50px; } #imgRotate { width: 100px; height: 100px; position: absolute; top: 50%; left: 50%; margin: -50px 0 0 -50px; } </style> </head> <body> <div id="div1"> <img id="img1" class="imgRotate" src="http://www.baidu.com/img/logo-yy.gif" /> <input id="input1" type="button" value="btn1"></input> </div> </body> <script type="text/javascript" src="jquery.min.js"></script> <script type="text/javascript"> 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); } $("#input1").click(function(){ $("img.imgRotate").attr("id","imgRotate"); rotateLeft("imgRotate",90); $("#imgRotate").attr("top","50%"); $("#imgRotate").attr("left","50%"); $("#imgRotate").attr("margin","-50px 0 0 -50px"); }); </script> </html> 測試結果：chrome下效果正常，但旋轉後img對象變為canvas對象；ie8下效果正常，旋轉後img對象仍為img對象。Matrix()參數較多，使用時需較多計算。 3 使用Microsoft提供的BasicImage對象 示例代碼： 代碼如下: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body> <img id="image" src="http://www.baidu.com/img/logo-yy.gif" /> <input id="input2" type="button" value="btn2"></input> </body> <script type="text/javascript" src="jquery.min.js"></script> <script type="text/javascript"> var num = 0; $("#input2").click(function(){ num = (num + 1) % 4; document.getElementById('image').style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation='+num+')'; }); </script> </html> 測試結果：chrome下不能旋轉；ie8下效果正常，旋轉後img對象仍為img對象。BasicImage()僅一個參數。 查看這三種方法的代碼會發現，本質上是一種解決方案：chrome下使用canvas對象實現，ie8下使用VML或者Matrix()或BasicImage()實現。本人近期改造一個組件：其中涉及到旋轉、放大圖片，由於jQueryRotate.js在ie8下會生成一個新的對象，導致放大圖片前選擇圖片時，需要進行特殊處理。後決定對chrome、ie8分開處理，chrome下使用jQueryRotate實現，ie8下使用BasicImage()實現，保證了代碼的簡潔性和可讀性。javascript排行
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