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大图片加载优化解决方案_html/css_WEB-ITnose

WBOY
WBOYOriginal
2016-06-21 08:52:251661browse

我们浏览页面上加载有大尺寸图片时,由于图片体积也比较大,我们会看到浏览器加载图片的时候会从上到下逐步显示图片,直到图片完整呈现在页面上,这样图片从空白区域到完全加载的过程显得比较突兀,用户体验比较差。

查看演示 下载源码

我们使用的解决办法是先加载一张很小的缩略图,它可能只有1K左右,并且按所需尺寸模糊显示,等到大尺寸图片下载好再完整显示大图。这样给用户的感觉是先加载模糊的图片,然后再是变清晰的图片,图片加载过程流畅,极大的提高用户体验。

HTML

我们准备一张大图,当然它尽可能的大,可能几百KB,甚至上MB。我们同时还制作一张缩略图,非常小,可能就1kb左右,我们可以将这张缩略图转换成Base64的图片,如下代码中,将data-antimoderate-idata属性值定义为base64图片。

<img  src="images/a.jpg" id="pic"   style="max-width:90%" data-antimoderate-idata="data:image/jpeg;base64,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" alt="大图片加载优化解决方案_html/css_WEB-ITnose" >

Javascript

在不做js处理时,我们还是会看到一张慢慢从上到下加载的大图。非常幸运的是, antimoderate.js 帮我们处理加载的问题,看如何使用它。

<script src="antimoderate.js"></script><script>    var img = document.getElementById('pic');    AntiModerate.process(img, img.getAttribute("data-antimoderate-idata"));</script>

Antimoderate.js使用了html5的canvans将图片做了处理,优先加载缩略图,并做模糊化,当大图下载完成时加载大图显示,使用它极大的加快了网页打开速度。

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