http://siwei.me/blog/posts/jquery-magnifit-popup

http://dimsemenov.com/plugins/magnific-popup/

使用步骤:

1. 添加 HTML: 

<a class="image-popup-vertical-fit" href="http://big_image.jpg" title="Caption. Can be aligned to any side and contain any HTML.">
	<img src="http://small_image.jpg" width="75" height="75">
</a>

2. 添加 js:

	
  // 图片点击后，全屏幕modal, 并显示大图
  $('.image-popup-vertical-fit').magnificPopup({
    type: 'image',
    closeOnContentClick: true,
    mainClass: 'mfp-no-margins mfp-with-zoom',
    image: {
      verticalFit: true
    },  
    //  这里是让图片的放大缩小有动画效果。
    zoom: {   
      enabled: true,
      duration: 300 // don't foget to change the duration also in CSS
    }   
  }); 

3. 再添加 CSS, 要有外链，

还要有下面这一段： 

/* padding-bottom and top for image */
.mfp-no-margins img.mfp-img {
	padding: 0;
}
/* position of shadow behind the image */
.mfp-no-margins .mfp-figure:after {
	top: 0;
	bottom: 0;
}
/* padding for main container */
.mfp-no-margins .mfp-container {
	padding: 0;
}

// 让黑色背景色有渐变效果
.mfp-with-zoom .mfp-container,
.mfp-with-zoom.mfp-bg {
	opacity: 0;
	-webkit-backface-visibility: hidden;
	-webkit-transition: all 0.3s ease-out; 
	-moz-transition: all 0.3s ease-out; 
	-o-transition: all 0.3s ease-out; 
	transition: all 0.3s ease-out;
}

.mfp-with-zoom.mfp-ready .mfp-container {
		opacity: 1;
}
.mfp-with-zoom.mfp-ready.mfp-bg {
		opacity: 0.8;
}

.mfp-with-zoom.mfp-removing .mfp-container, 
.mfp-with-zoom.mfp-removing.mfp-bg {
	opacity: 0;
}