JQuery外掛程式讓圖片旋轉任意角度且代碼極其簡單

引入下方的jquery.rotate.js檔案，然後通過$("選取器").rotate(角度);可以旋轉任意角度，

例如$("#rotate-image").rotate(45);把這句放在$(document).ready(function(){ });中

就是將id為rotate-image的圖片旋轉45度。

不過，貌似在Chrome中總是不顯示。

唉，找了兩個小時，才發現Chrome太坑爹了，沒法擷取圖片的長寬。

解決辦法是，把$("#rotate-image").rotate(45);放在

$(window).load(function(){ });中，因為在Chrome中圖片在執行$(document).ready(function(){ });中的語句時並沒有載入完圖片，坑爹啊。

另外可以更方便的通過調用$("選取器").rotateRight()和$("選取器").rotateLeft()來分別向右旋轉90度和向左旋轉90度。

 

jquery.rotate.js:

[javascript]
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); 
} 
 

摘自  cangkukuaimanle的專欄