function init(){ var img = document.getElementById('img1'); img.onclick = fn; } function fn(){ var img = document.getElementById('img1'); var width = parseInt(img.width,10); var height = parseInt(img.height,10); var imgStyle = img.style; var step = 10;
var t = Math.round(height/2); var r = Math.round(width/2); var b = t; var l = r;
function change(){ t = t - step; r = r + step; b = b + step; l = l - step; if(t < 0){ t = 0; } if(r > width) r = width; if(b > height) b = height; if(l < 0) l = 0;
imgStyle.clip = 'rect('+t+ 'px,' + r + 'px,' + b + 'px,' + l+ 'px)';
if(t == 0 && r == width && b == height && l ==0){ clearInterval(timer); } } var timer = setInterval(change,100); }